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Sample records for adaptation improves temporal

  1. Temporal and structural heterogeneities emerging in adaptive temporal networks

    Aoki, Takaaki; Gross, Thilo

    2015-01-01

    We introduce a model of adaptive temporal networks whose evolution is regulated by an interplay between node activity and dynamic exchange of information through links. We study the model by using a master equation approach. Starting from a homogeneous initial configuration, we show that temporal and structural heterogeneities, characteristic of real-world networks, spontaneously emerge. This theoretically tractable model thus contributes to the understanding of the dynamics of human activity and interaction networks.

  2. Temporal and structural heterogeneities emerging in adaptive temporal networks

    Aoki, Takaaki; Rocha, Luis E. C.; Gross, Thilo

    2016-04-01

    We introduce a model of adaptive temporal networks whose evolution is regulated by an interplay between node activity and dynamic exchange of information through links. We study the model by using a master equation approach. Starting from a homogeneous initial configuration, we show that temporal and structural heterogeneities, characteristic of real-world networks, spontaneously emerge. This theoretically tractable model thus contributes to the understanding of the dynamics of human activity and interaction networks.

  3. Improved Adaptive Fingerprint Binarization

    Bartunek, Josef Ström; Nilsson, Mikael; Nordberg, Jörgen; Claesson, Ingvar

    2008-01-01

    In this paper improvements to a previous work are presented. Removing the redundant artifacts in the fingerprint mask is introduced enhancing the final result. The proposed method is entirely adaptive process adjusting to each fingerprint without any further supervision of the user. Hence, the algorithm is insensitive to the characteristics of the fingerprint sensor and the various physical appearances of the fingerprints. Further, a detailed description of fingerprint mask generation not ful...

  4. Adaptation to speed in macaque middle temporal and medial superior temporal areas.

    Price, Nicholas S C; Born, Richard T

    2013-03-01

    The response of a sensory neuron to an unchanging stimulus typically adapts, showing decreases in response gain that are accompanied by changes in the shape of tuning curves. It remains unclear whether these changes arise purely due to spike rate adaptation within single neurons or whether they are dependent on network interactions between neurons. Further, it is unclear how the timescales of neural and perceptual adaptation are related. To examine this issue, we compared speed tuning of middle temporal (MT) and medial superior temporal neurons in macaque visual cortex after adaptation to two different reference speeds. For 75% of speed-tuned units, adaptation caused significant changes in tuning that could be explained equally well as lateral shifts, vertical gain changes, or both. These tuning changes occurred rapidly, as both neuronal firing rate and Fano factor showed no evidence of changing beyond the first 500 ms after motion onset, and the magnitude of tuning curve changes showed no difference between trials with adaptation durations shorter or longer than 1 s. Importantly, the magnitude of tuning shifts was correlated with the transient-sustained index, which measures a well characterized form of rapid response adaptation in MT, and is likely associated with changes at the level of neuronal networks. Tuning curves changed in a manner that increased neuronal sensitivity around the adapting speed, consistent with improvements in human and macaque psychophysical performance that we observed over the first several hundred ms of adaptation. PMID:23467352

  5. Temporal percolation of a susceptible adaptive network

    Valdez, L D; Braunstein, L A

    2013-01-01

    In the last decades, due to the appearance of many diseases such as SARS and the H1N1 flu strain, many authors studied the impact of the disease spreading in the evolution of the infected individuals using the susceptible-infected-recovered model. However, few authors focused on the temporal behavior of the susceptible individuals. Recently it was found that in an epidemic spreading, the dynamic of the size of the biggest susceptible cluster can be explained by a temporal node void percolation [Valdez et al PLoS ONE 7, e44188 (2012)]. It was shown that the size of the biggest susceptible cluster is the order parameter of this temporal percolation where the control parameter can be related to the number of links between susceptible individuals at a given time. As a consequence, there is a critical time at which the biggest susceptible cluster is destroyed. In this paper, we study the susceptible-infected-recovered model in an adaptive network where an intermittent social distancing strategy is applied. In this...

  6. Simultaneous Spectral Temporal Adaptive Raman Spectrometer - SSTARS

    Blacksberg, Jordana

    2010-01-01

    Raman spectroscopy is a prime candidate for the next generation of planetary instruments, as it addresses the primary goal of mineralogical analysis, which is structure and composition. However, large fluorescence return from many mineral samples under visible light excitation can render Raman spectra unattainable. Using the described approach, Raman and fluorescence, which occur on different time scales, can be simultaneously obtained from mineral samples using a compact instrument in a planetary environment. This new approach is taken based on the use of time-resolved spectroscopy for removing the fluorescence background from Raman spectra in the laboratory. In the SSTARS instrument, a visible excitation source (a green, pulsed laser) is used to generate Raman and fluorescence signals in a mineral sample. A spectral notch filter eliminates the directly reflected beam. A grating then disperses the signal spectrally, and a streak camera provides temporal resolution. The output of the streak camera is imaged on the CCD (charge-coupled device), and the data are read out electronically. By adjusting the sweep speed of the streak camera, anywhere from picoseconds to milliseconds, it is possible to resolve Raman spectra from numerous fluorescence spectra in the same sample. The key features of SSTARS include a compact streak tube capable of picosecond time resolution for collection of simultaneous spectral and temporal information, adaptive streak tube electronics that can rapidly change from one sweep rate to another over ranges of picoseconds to milliseconds, enabling collection of both Raman and fluorescence signatures versus time and wavelength, and Synchroscan integration that allows for a compact, low-power laser without compromising ultimate sensitivity.

  7. Motor Activity Improves Temporal Expectancy

    Fautrelle, Lilian; Mareschal, Denis; French, Robert; Addyman, Caspar; Thomas, Elizabeth

    2015-01-01

    Certain brain areas involved in interval timing are also important in motor activity. This raises the possibility that motor activity might influence interval timing. To test this hypothe- sis, we assessed interval timing in healthy adults following different types of training. The pre- and post-training tasks consisted of a button press in response to the presentation of a rhythmic visual stimulus. Alterations in temporal expectancy were evaluated by measuring response times. Training consis...

  8. Temporal recalibration in vocalization induced by adaptation of delayed auditory feedback.

    Kosuke Yamamoto

    Full Text Available BACKGROUND: We ordinarily perceive our voice sound as occurring simultaneously with vocal production, but the sense of simultaneity in vocalization can be easily interrupted by delayed auditory feedback (DAF. DAF causes normal people to have difficulty speaking fluently but helps people with stuttering to improve speech fluency. However, the underlying temporal mechanism for integrating the motor production of voice and the auditory perception of vocal sound remains unclear. In this study, we investigated the temporal tuning mechanism integrating vocal sensory and voice sounds under DAF with an adaptation technique. METHODS AND FINDINGS: Participants produced a single voice sound repeatedly with specific delay times of DAF (0, 66, 133 ms during three minutes to induce 'Lag Adaptation'. They then judged the simultaneity between motor sensation and vocal sound given feedback. We found that lag adaptation induced a shift in simultaneity responses toward the adapted auditory delays. This indicates that the temporal tuning mechanism in vocalization can be temporally recalibrated after prolonged exposure to delayed vocal sounds. Furthermore, we found that the temporal recalibration in vocalization can be affected by averaging delay times in the adaptation phase. CONCLUSIONS: These findings suggest vocalization is finely tuned by the temporal recalibration mechanism, which acutely monitors the integration of temporal delays between motor sensation and vocal sound.

  9. Temporal adaptation enhances efficient contrast gain control on natural images.

    Fabian Sinz

    Full Text Available Divisive normalization in primary visual cortex has been linked to adaptation to natural image statistics in accordance to Barlow's redundancy reduction hypothesis. Using recent advances in natural image modeling, we show that the previously studied static model of divisive normalization is rather inefficient in reducing local contrast correlations, but that a simple temporal contrast adaptation mechanism of the half-saturation constant can substantially increase its efficiency. Our findings reveal the experimentally observed temporal dynamics of divisive normalization to be critical for redundancy reduction.

  10. A comparison between temporal and subband minimum variance adaptive beamforming

    Diamantis, Konstantinos; Voxen, Iben Holfort; Greenaway, Alan H.;

    2014-01-01

    and subband approaches. From a cyst phantom and for 128 emissions, the contrast level is calculated at -54 dB and -63 dB respectively at the same depth, with the initial shape of the cyst being preserved in contrast to conventional beamforming. The difference between the two adaptive beamformers is......This paper compares the performance between temporal and subband Minimum Variance (MV) beamformers for medical ultrasound imaging. Both adaptive methods provide an optimized set of apodization weights but are implemented in the time and frequency domains respectively. Their performance is evaluated...... with simulated synthetic aperture data obtained from Field II and is quantified by the Full-Width-Half-Maximum (FWHM), the Peak-Side-Lobe level (PSL) and the contrast level. From a point phantom, a full sequence of 128 emissions with one transducer element transmitting and all 128 elements receiving...

  11. Spatio-Temporal Video Object Segmentation via Scale-Adaptive 3D Structure Tensor

    Hai-Yun Wang

    2004-06-01

    Full Text Available To address multiple motions and deformable objects' motions encountered in existing region-based approaches, an automatic video object (VO segmentation methodology is proposed in this paper by exploiting the duality of image segmentation and motion estimation such that spatial and temporal information could assist each other to jointly yield much improved segmentation results. The key novelties of our method are (1 scale-adaptive tensor computation, (2 spatial-constrained motion mask generation without invoking dense motion-field computation, (3 rigidity analysis, (4 motion mask generation and selection, and (5 motion-constrained spatial region merging. Experimental results demonstrate that these novelties jointly contribute much more accurate VO segmentation both in spatial and temporal domains.

  12. Improving the privacy of optical steganography with temporal phase masks.

    Wang, Z; Fok, M P; Xu, L; Chang, J; Prucnal, P R

    2010-03-15

    Temporal phase modulation of spread stealth signals is proposed and demonstrated to improve optical steganography transmission privacy. After phase modulation, the temporally spread stealth signal has a more complex spectral-phase-temporal relationship, such that the original temporal profile cannot be restored when only dispersion compensation is applied to the temporally spread stealth signals. Therefore, it increases the difficulty for the eavesdropper to detect and intercept the stealth channel that is hidden under a public transmission, even with a correct dispersion compensation device. The experimental results demonstrate the feasibility of this approach and display insignificant degradation in transmission performance, compared to the conventional stealth transmission without temporal phase modulation. The proposed system can also work without a clock transmission for signal synchronization. Our analysis and simulation results show that it is difficult for the adversary to detect the existence of the stealth transmission, or find the correct phase mask to recover the stealth signals. PMID:20389629

  13. Realigning thunder and lightning: temporal adaptation to spatiotemporally distant events.

    Jordi Navarra

    Full Text Available The brain is able to realign asynchronous signals that approximately coincide in both space and time. Given that many experience-based links between visual and auditory stimuli are established in the absence of spatiotemporal proximity, we investigated whether or not temporal realignment arises in these conditions. Participants received a 3-min exposure to visual and auditory stimuli that were separated by 706 ms and appeared either from the same (Experiment 1 or from different spatial positions (Experiment 2. A simultaneity judgment task (SJ was administered right afterwards. Temporal realignment between vision and audition was observed, in both Experiment 1 and 2, when comparing the participants' SJs after this exposure phase with those obtained after a baseline exposure to audiovisual synchrony. However, this effect was present only when the visual stimuli preceded the auditory stimuli during the exposure to asynchrony. A similar pattern of results (temporal realignment after exposure to visual-leading asynchrony but not after exposure to auditory-leading asynchrony was obtained using temporal order judgments (TOJs instead of SJs (Experiment 3. Taken together, these results suggest that temporal recalibration still occurs for visual and auditory stimuli that fall clearly outside the so-called temporal window for multisensory integration and appear from different spatial positions. This temporal realignment may be modulated by long-term experience with the kind of asynchrony (vision-leading that we most frequently encounter in the outside world (e.g., while perceiving distant events.

  14. Controling contagious processes on temporal networks via adaptive rewiring

    Belik, Vitaly; Hövel, Philipp

    2015-01-01

    We consider recurrent contagious processes on a time-varying network. As a control procedure to mitigate the epidemic, we propose an adaptive rewiring mechanism for temporary isolation of infected nodes upon their detection. As a case study, we investigate the network of pig trade in Germany. Based on extensive numerical simulations for a wide range of parameters, we demonstrate that the adaptation mechanism leads to a significant extension of the parameter range, for which most of the index nodes (origins of the epidemic) lead to vanishing epidemics. We find that diseases with detection times around a week and infectious periods up to 3 months can be effectively controlled. Furthermore the performance of adaptation is very heterogeneous with respect to the index node. We identify index nodes that are most responsive to the adaptation strategy and quantify the success of the proposed adaptation scheme in dependence on the infectious period and detection times.

  15. Improvement of Adaptive Cruise Control Performance

    Nakagami Takashi

    2010-01-01

    Full Text Available This paper describes the Adaptive Cruise Control system (ACC, a system which reduces the driving burden on the driver. The ACC system primarily supports four driving modes on the road and controls the acceleration and deceleration of the vehicle in order to maintain a set speed or to avoid a crash. This paper proposes more accurate methods of detecting the preceding vehicle by radar while cornering, with consideration for the vehicle sideslip angle, and also of controlling the distance between vehicles. By making full use of the proposed identification logic for preceding vehicles and path estimation logic, an improvement in driving stability was achieved.

  16. Flicker Adaptation of Low-Level Cortical Visual Neurons Contributes to Temporal Dilation

    Ortega, Laura; Guzman-Martinez, Emmanuel; Grabowecky, Marcia; Suzuki, Satoru

    2012-01-01

    Several seconds of adaptation to a flickered stimulus causes a subsequent brief static stimulus to appear longer in duration. Nonsensory factors, such as increased arousal and attention, have been thought to mediate this flicker-based temporal-dilation aftereffect. In this study, we provide evidence that adaptation of low-level cortical visual…

  17. Safety culture improvement. An adaptive management framework

    After the Chernobyl nuclear accident in 1986, the International Atomic Energy Agency (IAEA) established the safety culture concept as a proactive mean to contribute to safety improvement, starting a worldwide safety culture enhancement program within nuclear organizations mainly focused on nuclear power plants. More recently, the safety culture concept has been extended to non-power applications such as nuclear research reactors and nuclear technological research and development organizations. In 1999, the Nuclear Engineering Institute (IEN), a research and technological development unit of the Brazilian Nuclear Energy Commission (CNEN), started a management change program aiming at improving its performance level of excellence. This change program has been developed assuming the occurrence of complex causal inter-relationships between the organizational culture and the implementation of the management process. A systematic and adaptive management framework comprised of a safety culture improvement practice integrated to a management process based on the Criteria for Excellence of the Brazilian Quality Award Model, has been developed and implemented at IEN. The case study has demonstrated that the developed framework makes possible an effective safety culture improvement and simultaneously facilitates an effective implementation of the management process, thus providing some governance to the change program. (author)

  18. Evolution of spatio-temporal drought characteristics: validation, projections and effect of adaptation scenarios

    J.-P. Vidal

    2012-02-01

    Full Text Available Drought events develop in both space and time and they are therefore best described through summary joint spatio-temporal characteristics, like mean duration, mean affected area and total magnitude. This paper addresses the issue of future projections of such characteristics of drought events over France through three main research questions: (1 are downscaled climate projections able to reproduce spatio-temporal characteristics of meteorological and agricultural droughts in France over a present-day period? (2 How such characteristics will evolve over the 21st century? (3 How to use standardized drought indices to represent theoretical adaptation scenarios? These questions are addressed using the Isba land surface model, downscaled climate projections from the ARPEGE General Circulation Model under three emissions scenarios, as well as results from a previously performed 50-yr multilevel and multiscale drought reanalysis over France. Spatio-temporal characteristics of meteorological and agricultural drought events are computed using the Standardized Precipitation Index and the Standardized Soil Wetness Index, respectively, and for time scales of 3 and 12 months. Results first show that the distributions of joint spatio-temporal characteristics of observed events are well reproduced by the downscaled hydroclimate projections over a present-day period. All spatio-temporal characteristics of drought events are then found to dramatically increase over the 21st century, with stronger changes for agricultural droughts. Two theoretical adaptation scenarios are eventually built based on hypotheses of adaptation to evolving climate and hydrological normals, either retrospective or prospective, and by taking advantage of the statistical properties of the standardized drought indices. The perceived spatio-temporal characteristics of drought events derived from these theoretical adaptation scenarios show much reduced changes, but they call for more

  19. Evolution of spatio-temporal drought characteristics: validation, projections and effect of adaptation scenarios

    J.-P. Vidal

    2012-08-01

    Full Text Available Drought events develop in both space and time and they are therefore best described through summary joint spatio-temporal characteristics, such as mean duration, mean affected area and total magnitude. This paper addresses the issue of future projections of such characteristics of drought events over France through three main research questions: (1 Are downscaled climate projections able to simulate spatio-temporal characteristics of meteorological and agricultural droughts in France over a present-day period? (2 How such characteristics will evolve over the 21st century? (3 How to use standardized drought indices to represent theoretical adaptation scenarios? These questions are addressed using the Isba land surface model, downscaled climate projections from the ARPEGE General Circulation Model under three emissions scenarios, as well as results from a previously performed 50-yr multilevel and multiscale drought reanalysis over France. Spatio-temporal characteristics of meteorological and agricultural drought events are computed using the Standardized Precipitation Index and the Standardized Soil Wetness Index, respectively, and for time scales of 3 and 12 months. Results first show that the distributions of joint spatio-temporal characteristics of observed events are well simulated by the downscaled hydroclimate projections over a present-day period. All spatio-temporal characteristics of drought events are then found to dramatically increase over the 21st century, with stronger changes for agricultural droughts. Two theoretical adaptation scenarios are eventually built based on hypotheses of adaptation to evolving climate and hydrological normals, either retrospective or prospective. The perceived spatio-temporal characteristics of drought events derived from these theoretical adaptation scenarios show much reduced changes, but they call for more realistic scenarios at both the catchment and national scale in order to accurately assess the

  20. Improving information for community-based adaptation

    Huq, Saleemul

    2011-10-15

    Community-based adaptation aims to empower local people to cope with and plan for the impacts of climate change. In a world where knowledge equals power, you could be forgiven for thinking that enabling this type of adaptation boils down to providing local people with information. Conventional approaches to planning adaptation rely on 'expert' advice and credible 'science' from authoritative information providers such as the Intergovernmental Panel on Climate Change. But to truly support the needs of local communities, this information needs to be more site-specific, more user-friendly and more inclusive of traditional knowledge and existing coping practices.

  1. Evolutionary adaptations for the temporal processing of natural sounds by the anuran peripheral auditory system.

    Schrode, Katrina M; Bee, Mark A

    2015-03-01

    Sensory systems function most efficiently when processing natural stimuli, such as vocalizations, and it is thought that this reflects evolutionary adaptation. Among the best-described examples of evolutionary adaptation in the auditory system are the frequent matches between spectral tuning in both the peripheral and central auditory systems of anurans (frogs and toads) and the frequency spectra of conspecific calls. Tuning to the temporal properties of conspecific calls is less well established, and in anurans has so far been documented only in the central auditory system. Using auditory-evoked potentials, we asked whether there are species-specific or sex-specific adaptations of the auditory systems of gray treefrogs (Hyla chrysoscelis) and green treefrogs (H. cinerea) to the temporal modulations present in conspecific calls. Modulation rate transfer functions (MRTFs) constructed from auditory steady-state responses revealed that each species was more sensitive than the other to the modulation rates typical of conspecific advertisement calls. In addition, auditory brainstem responses (ABRs) to paired clicks indicated relatively better temporal resolution in green treefrogs, which could represent an adaptation to the faster modulation rates present in the calls of this species. MRTFs and recovery of ABRs to paired clicks were generally similar between the sexes, and we found no evidence that males were more sensitive than females to the temporal modulation patterns characteristic of the aggressive calls used in male-male competition. Together, our results suggest that efficient processing of the temporal properties of behaviorally relevant sounds begins at potentially very early stages of the anuran auditory system that include the periphery. PMID:25617467

  2. Adaptive Feedback Improving Learningful Conversations at Workplace

    Gaeta, Matteo; Mangione, Giuseppina Rita; Miranda, Sergio; Orciuoli, Francesco

    2013-01-01

    This work proposes the definition of an Adaptive Conversation-based Learning System (ACLS) able to foster computer-mediated tutorial dialogues at the workplace in order to increase the probability to generate meaningful learning during conversations. ACLS provides a virtual assistant selecting the best partner to involve in the conversation and…

  3. Improving foreground detection for adaptive background segmentation

    Huerta, Iván; Rowe, Daniel; Gonzàlez, Jordi; Villanueva, Juan J.

    2006-01-01

    This paper tries to manage with the nonincorporation of erroneous foreground objects to the background model, and the incorporation of those detected objects which cease their movement. These newly motionless foreground objects should be handled in security domains such as video surveillance. This paper uses an adaptive background modelling algorithm for moving object detection. Those detected objects which present no motion are identified and added into the background model, so that they wil...

  4. Video Enhancement Using Adaptive Spatio-Temporal Connective Filter and Piecewise Mapping

    Wang Chao

    2008-01-01

    Full Text Available This paper presents a novel video enhancement system based on an adaptive spatio-temporal connective (ASTC noise filter and an adaptive piecewise mapping function (APMF. For ill-exposed videos or those with much noise, we first introduce a novel local image statistic to identify impulse noise pixels, and then incorporate it into the classical bilateral filter to form ASTC, aiming to reduce the mixture of the most two common types of noises—Gaussian and impulse noises in spatial and temporal directions. After noise removal, we enhance the video contrast with APMF based on the statistical information of frame segmentation results. The experiment results demonstrate that, for diverse low-quality videos corrupted by mixed noise, underexposure, overexposure, or any mixture of the above, the proposed system can automatically produce satisfactory results.

  5. Codifying temporal characteristics of Jewett components to improve Jewett transform

    Jewett Transform is not yet, it is being. First ideas on this metaphor are from 1980 while monitoring cerebral function. It was conceived in contrast with Fourier Transform. Its application is limited to Auditory Brain Stem Responses. It uses a non-orthogonal physiologically rooted basis. Non-orthogonal basis has limited power in front of orthogonal basis: no analytical method exists to evaluate the corresponding transforms and numerical methods are required. In previous works, numerical methods were replaced for by trained artificial neural networks. Jewett transform was applied to increase the training set. Being a physiologically inspired basis, it promises better understanding of analysis of these evoked responses. It is envisioned that diverse new transforms, tailored to different problem specificity are to emerge. Considering the short temporal influence of Jewett components, it is stated that codifying temporal characteristics of Jewett components can be used to improve Jewett Transform. Previously used neural network was modified. Output vector codes are built up by grouping components instead of grouping parameters. This allows synaptic pruning in the artificial neural network. Only a fraction (0.49) of the previous network weights is used. Mean square error in fitting signal to model are acceptable (mean ε<0.3%, n= 600). Memorization is eliminated

  6. Spatial and temporal aspects of chromatic adaptation and their functional significance for colour constancy.

    Werner, Annette

    2014-11-01

    Illumination in natural scenes changes at multiple temporal and spatial scales: slow changes in global illumination occur in the course of a day, and we encounter fast and localised illumination changes when visually exploring the non-uniform light field of three-dimensional scenes; in addition, very long-term chromatic variations may come from the environment, like for example seasonal changes. In this context, I consider the temporal and spatial properties of chromatic adaptation and discuss their functional significance for colour constancy in three-dimensional scenes. A process of fast spatial tuning in chromatic adaptation is proposed as a possible sensory mechanism for linking colour constancy to the spatial structure of a scene. The observed middlewavelength selectivity of this process is particularly suitable for adaptation to the mean chromaticity and the compensation of interreflections in natural scenes. Two types of sensory colour constancy are distinguished, based on the functional differences of their temporal and spatial scales: a slow type, operating at a global scale for the compensation of the ambient illumination; and a fast colour constancy, which is locally restricted and well suited to compensate region-specific variations in the light field of three dimensional scenes. PMID:25449338

  7. Temporal learning and list-level proportion congruency: conflict adaptation or learning when to respond?

    Schmidt, James R

    2013-01-01

    The current report presents a temporal learning account as a potential alternative to the conflict adaptation account of list-level proportion congruent effects in the Stroop paradigm. Specifically, retrieval of information about response times on previous trials influences a participant's preparedness to respond at a similar time on following trials. First, an adaptation of the Parallel Episodic Processing (PEP) model is presented, and a list-level effect is produced with a temporal learning mechanism. Next, linear mixed effect model analyses show that temporal learning biases are present in list-level proportion congruent data. A non-conflict experiment is then presented in which a list-level effect is observed with a contrast, rather than congruency, manipulation. Analyses of the experimental and simulated data could not, however, provide a clear picture of whether temporal learning was the sole contributor to the list-level proportion congruent effect. These results do, however, demonstrate that caution is warranted when interpreting list-level proportion congruent effects. PMID:24312413

  8. Adaptive Landing Gear: Optimum Control Strategy and Potential for Improvement

    Grzegorz Mikułowski; Łukasz Jankowski

    2009-01-01

    An adaptive landing gear is a landing gear (LG) capable of active adaptation to particular landing conditions by means of controlled hydraulic force. The objective of the adaptive control is to mitigate the peak force transferred to the aircraft structure during touch-down, and thus to limit the structural fatigue factor. This paper investigates the ultimate limits for improvement due to various strategies of active control. Five strategies are proposed and investigated numerically using a~va...

  9. An Adaptive Middleware for Improved Computational Performance

    Bonnichsen, Lars Frydendal

    The performance improvements in computer systems over the past 60 years have been fueled by an exponential increase in energy efficiency. In recent years, the phenomenon known as the end of Dennard’s scaling has slowed energy efficiency improvements — but improving computer energy efficiency is m...... which we hope to simplify by analyzing the realities of modern computers, and providing guidelines explaining how to get the most performance out of them....

  10. “Lucky Averaging”: Quality improvement on Adaptive Optics Scanning Laser Ophthalmoscope Images

    Huang, Gang; Zhong, Zhangyi; Zou, Weiyao; Burns, Stephen A.

    2011-01-01

    Adaptive optics(AO) has greatly improved retinal image resolution. However, even with AO, temporal and spatial variations in image quality still occur due to wavefront fluctuations, intra-frame focus shifts and other factors. As a result, aligning and averaging images can produce a mean image that has lower resolution or contrast than the best images within a sequence. To address this, we propose an image post-processing scheme called “lucky averaging”, analogous to lucky imaging (Fried, 1978...

  11. Adaption of the temporal correlation coefficient calculation for temporal networks (applied to a real-world pig trade network).

    Büttner, Kathrin; Salau, Jennifer; Krieter, Joachim

    2016-01-01

    The average topological overlap of two graphs of two consecutive time steps measures the amount of changes in the edge configuration between the two snapshots. This value has to be zero if the edge configuration changes completely and one if the two consecutive graphs are identical. Current methods depend on the number of nodes in the network or on the maximal number of connected nodes in the consecutive time steps. In the first case, this methodology breaks down if there are nodes with no edges. In the second case, it fails if the maximal number of active nodes is larger than the maximal number of connected nodes. In the following, an adaption of the calculation of the temporal correlation coefficient and of the topological overlap of the graph between two consecutive time steps is presented, which shows the expected behaviour mentioned above. The newly proposed adaption uses the maximal number of active nodes, i.e. the number of nodes with at least one edge, for the calculation of the topological overlap. The three methods were compared with the help of vivid example networks to reveal the differences between the proposed notations. Furthermore, these three calculation methods were applied to a real-world network of animal movements in order to detect influences of the network structure on the outcome of the different methods. PMID:27026862

  12. Adaptive Filtering Queueing for Improving Fairness

    Jui-Pin Yang

    2015-06-01

    Full Text Available In this paper, we propose a scalable and efficient Active Queue Management (AQM scheme to provide fair bandwidth sharing when traffic is congested dubbed Adaptive Filtering Queueing (AFQ. First, AFQ identifies the filtering level of an arriving packet by comparing it with a flow label selected at random from the first level to an estimated level in the filtering level table. Based on the accepted traffic estimation and the previous fair filtering level, AFQ updates the fair filtering level. Next, AFQ uses a simple packet-dropping algorithm to determine whether arriving packets are accepted or discarded. To enhance AFQ’s feasibility in high-speed networks, we propose a two-layer mapping mechanism to effectively simplify the packet comparison operations. Simulation results demonstrate that AFQ achieves optimal fairness when compared with Rotating Preference Queues (RPQ, Core-Stateless Fair Queueing (CSFQ, CHOose and Keep for responsive flows, CHOose and Kill for unresponsive flows (CHOKe and First-In First-Out (FIFO schemes under a variety of traffic conditions.

  13. Adaptively measuring the temporal shape of ultrashort single photons for higher-dimensional quantum information processing

    Polycarpou, Constantina; Venturi, Giovanni; Zavatta, Alessandro; Bellini, Marco

    2011-01-01

    A photon is the single excitation of a particular spatiotemporal mode of the electromagnetic field. A precise knowledge of the mode structure is therefore essential for its processing and detection, as well as for applying generic quantum light states to novel technologies. Here we demonstrate an adaptive scheme for reconstructing the arbitrary amplitude and phase spectro-temporal profile of an ultrashort single-photon pulse. The method combines techniques from the fields of ultrafast coherent control and quantum optics to map the mode of a fragile quantum state onto that of an intense coherent field. In addition, we show that the possibility of generating and detecting quantum states in multiple spectro-temporal modes may serve as a basis for encoding qubits (and qudits) into single, broadband, ultrashort, photons. Providing access to a much larger Hilbert space, this scheme may boost the capacity of current quantum information protocols.

  14. Optic flow improves adaptability of spatiotemporal characteristics during split-belt locomotor adaptation with tactile stimulation.

    Eikema, Diderik Jan A; Chien, Jung Hung; Stergiou, Nicholas; Myers, Sara A; Scott-Pandorf, Melissa M; Bloomberg, Jacob J; Mukherjee, Mukul

    2016-02-01

    similar in the two groups, suggesting that temporal parameters are not modified by optic flow. However, whereas the TC group displayed significant stance time asymmetries during the post-treadmill session, such aftereffects were absent in the VRT group. The results indicated that the enhanced transfer resulting from exposure to plantar cutaneous vibration during adaptation was alleviated by optic flow information. The presence of visual self-motion information may have reduced proprioceptive gain during learning. Thus, during overground walking, the learned proprioceptive split-belt pattern is more rapidly overridden by visual input due to its increased relative gain. The results suggest that when visual stimulation is provided during adaptive training, the system acquires the novel movement dynamics while maintaining the ability to flexibly adapt to different environments. PMID:26525712

  15. Temporal Scalability through Adaptive -Band Filter Banks for Robust H.264/MPEG-4 AVC Video Coding

    Pau G

    2006-01-01

    Full Text Available This paper presents different structures that use adaptive -band hierarchical filter banks for temporal scalability. Open-loop and closed-loop configurations are introduced and illustrated using existing video codecs. In particular, it is shown that the H.264/MPEG-4 AVC codec allows us to introduce scalability by frame shuffling operations, thus keeping backward compatibility with the standard. The large set of shuffling patterns introduced here can be exploited to adapt the encoding process to the video content features, as well as to the user equipment and transmission channel characteristics. Furthermore, simulation results show that this scalability is obtained with no degradation in terms of subjective and objective quality in error-free environments, while in error-prone channels the scalable versions provide increased robustness.

  16. Adaptation to Temporally Fluctuating Environments by the Evolution of Maternal Effects.

    Dey, Snigdhadip; Proulx, Stephen R; Teotónio, Henrique

    2016-02-01

    All organisms live in temporally fluctuating environments. Theory predicts that the evolution of deterministic maternal effects (i.e., anticipatory maternal effects or transgenerational phenotypic plasticity) underlies adaptation to environments that fluctuate in a predictably alternating fashion over maternal-offspring generations. In contrast, randomizing maternal effects (i.e., diversifying and conservative bet-hedging), are expected to evolve in response to unpredictably fluctuating environments. Although maternal effects are common, evidence for their adaptive significance is equivocal since they can easily evolve as a correlated response to maternal selection and may or may not increase the future fitness of offspring. Using the hermaphroditic nematode Caenorhabditis elegans, we here show that the experimental evolution of maternal glycogen provisioning underlies adaptation to a fluctuating normoxia-anoxia hatching environment by increasing embryo survival under anoxia. In strictly alternating environments, we found that hermaphrodites evolved the ability to increase embryo glycogen provisioning when they experienced normoxia and to decrease embryo glycogen provisioning when they experienced anoxia. At odds with existing theory, however, populations facing irregularly fluctuating normoxia-anoxia hatching environments failed to evolve randomizing maternal effects. Instead, adaptation in these populations may have occurred through the evolution of fitness effects that percolate over multiple generations, as they maintained considerably high expected growth rates during experimental evolution despite evolving reduced fecundity and reduced embryo survival under one or two generations of anoxia. We develop theoretical models that explain why adaptation to a wide range of patterns of environmental fluctuations hinges on the existence of deterministic maternal effects, and that such deterministic maternal effects are more likely to contribute to adaptation than

  17. Temporal features of postural adaptation strategy to prolonged and repeatable balance perturbation.

    Schmid, Micaela; Sozzi, Stefania

    2016-08-15

    Aim of this study was to get insight into the features of the postural adaptation process, occurring during a continuous 3-min and 0.6Hz horizontal sinusoidal oscillation of the body support base. We hypothesized an ongoing temporal organization of the balancing strategy that gradually becomes fine-tuned and more coordinated with the platform movement. The trial was divided into oscillation cycles and for each cycle: leg muscles activity and temporal relationship between Centre of Mass and Centre of Pressure A-P position were analyzed. The results of each cycle were grouped in time-windows of 10 successive cycles (time windows of 16.6s). Muscle activity was initially prominent and diminished progressively. The major burst of Tibialis Anterior (TA) muscle always occurred at the same time instant of the platform oscillation cycle, in advance with respect to the platform posterior turning point. This burst produced a body forward rotation that was delayed throughout the task. During prolonged and repeatable balance perturbation, an ongoing postural adaptation process occurs. When the effects of the perturbation become predictable, the CNS scales the level of muscle activity to counteracting the destabilizing effects of the perturbations. Furthermore, the CNS tunes the kinematics and the kinetic responses optimally by slightly delaying the onset of the body forward rotation, maintaining unchanged the time-pattern of postural muscle activation. PMID:27291456

  18. Adaptive Landing Gear: Optimum Control Strategy and Potential for Improvement

    Grzegorz Mikułowski

    2009-01-01

    Full Text Available An adaptive landing gear is a landing gear (LG capable of active adaptation to particular landing conditions by means of controlled hydraulic force. The objective of the adaptive control is to mitigate the peak force transferred to the aircraft structure during touch-down, and thus to limit the structural fatigue factor. This paper investigates the ultimate limits for improvement due to various strategies of active control. Five strategies are proposed and investigated numerically using a~validated model of a real, passive landing gear as a reference. Potential for improvement is estimated statistically in terms of the mean and median (significant peak strut forces as well as in terms of the extended safe sinking velocity range. Three control strategies are verified experimentally using a laboratory test stand.

  19. Adaptive data analysis for characterizing the temporal variability of the solar resource

    Bengulescu, Marc; Blanc, Philippe; Wald, Lucien

    2016-04-01

    One of the key challenges associated with the large-scale penetration of solar power is the inherent spatio-temporal variability of the solar radiation impinging on the surface. Particular methods are currently employed to measure, estimate or forecast the extent and availability of the solar resource depending on the effective spatial and temporal scales of interest, such as numerical weather prediction models, satellite-based estimates, sky-imagers or in-situ ground measurements. Here we present a method for characterizing the intrinsic time-scales of the solar resource variability. The study deals with decennial time-series of daily values of the surface solar irradiance (SSI) issued from high-quality BSRN ground measurement stations. Geophysical signals, such as the SSI time-series under scrutiny, are often the result of non-linear interactions of physical processes that are also often under natural or anthropogenic non-stationary forcings. Therefore, an adaptive data analysis technique is employed that makes no beforehand assumptions about the data: neither linearity, nor stationarity of the signal is assumed. The method, called the Hilbert-Huang transform, first extracts all the embedded oscillations that have a similar time-scale, to which it then applies Hilbert spectral analysis. A time-frequency-energy representation of the signal is thus constructed, which reveals the time-varying character of the intrinsic temporal scales of variability (frequency modulation), along with any fluctuations in the intensity of the signal at the corresponding scale (amplitude modulation). In order to test whether the features extracted from the data are the expression of deterministic physical processes, as opposed to being stochastic realizations of various background processes (i.e. noise), a novel, adaptive null-hypothesis based on the statistical properties of noise is employed. It is shown that the data, irrespective of the geographical conditions, shares common time

  20. Improved Step Size Adaptation for the MO-CMA-ES

    Voß, T.; Hansen, N.; Igel, Christian

    elitist, rank-based selection procedure. In contrast, we propose to regard a mutation as successful if the offspring is selected into the next parental population. This criterion is easier to implement and reduces the computational complexity of the MO-CMA-ES, in particular of its steady-state variant...... covariance matrix adaptation evolution strategy (CMA-ES). Step sizes (i.e., mutation strengths) are adapted on individual-level using an improved implementation of the 1/5-th success rule. In the original MO-CMA-ES, a mutation is regarded as successful if the offspring ranks better than its parent in the...

  1. Microgeographical population structure and adaptation in Atlantic cod Gadus morhua: spatio-temporal insights from gene-associated DNA markers

    Poulsen, Nina Aagaard; Hemmer-Hansen, Jakob; Loeschcke, V.; Carvalho, G.R.; Eg Nielsen, Einar

    2011-01-01

    populations, indicating long-term temporal adaptive stability driven by strong local selection. In an environmentally dynamic area, on the other hand, patterns of genetic structuring were more variable. Overall, our results not only suggest separation of populations under both evolutionary and ecological......Recent technical advances have stimulated studies on spatial scales of adaptive genetic variation in marine fishes. However, very few studies have combined spatial and temporal sampling to investigate adaptive genetic structuring at local and microgeographical scales, i.e. scales at which neutral...... stability, we included long- and short-term (i.e. from 24 to 38 and from 8 to 11 yr, ­respectively) temporally replicated samples from a subset of populations. As expected, we found very low levels of neutral genetic population structure (FST = 0.003). Three specific loci, however, showed highly elevated...

  2. À Table! Improving Temporal Navigation in Soccer Ranking Tables

    Perin, Charles; Vuillemot, Romain; Fekete, Jean-Daniel

    2014-01-01

    International audience This article introduces A Table!, an enhanced soccer ranking table providing temporal navigation by combining two novel interaction techniques. Ranking tables order soccer teams represented as rows, according to values of columns containing attributes e.g., accumulated points, or number of scored goals. Because they represent a snapshot of a championship at a time t, tables are regularly updated with new results. Such updates usually change the rows order, which make...

  3. An improved adaptive wavelet shrinkage for ultrasound despeckling

    P Nirmala Devi; R Asokan

    2014-08-01

    Ultrasound imaging is the most widely used medical diagnostic technique for clinical decision making, due to its ability to make real time imaging for moving structures, low cost and safety. However, its usefulness is degraded by the presence of signal dependent speckle noise. Several wavelet-based denoising schemes have been reported in the literature for the removal of speckle noise. This study proposes a new and improved adaptive wavelet shrinkage in the translational invariant domain. It exploits the knowledge of the correlation of the wavelet coefficients within and across the resolution scales. A preliminary coefficient classification representing useful image information and noise is performed with a novel inter-scale dependency measure. The spatial context adaptation of the wavelet coefficients within a subband is achieved by a local spatial adaptivity indicator, determined by using a truncation threshold. A weighted signal variance is estimated based on this measure and used in the determination of a subband adaptive threshold. The proposed thresholding function aims to reduce the fixed bias of the soft thresholding approach. Experiments conducted with the proposed filter are compared with the existing filtering algorithms in terms of Peak-Signal to Noise Ratio (PSNR), Mean Square Error (MSE), Structural Similarity IndexMeasure (SSIM), Equivalent Number of Looks (ENL) and Edge Preservation Index (EPI). A comparison of the results shows that the proposed filter achieves an improvement in terms of quantitative measures and in terms of visual quality of the images.

  4. Adaptive temporal and wavefront aberration correction for ultrafast lasers with a membrane deformable mirror

    Sherman, Leah Bruner

    Two adaptive optic systems for correction of either temporal phase error and wavefront errors for ultrafast pulses are demonstrated. These systems consists of a computer controlled micromachined membrane deformable mirror (MMDM) and a genetic learning algorithm (GA). Nonlinear excitation such as two-photon fluorescence or second harmonic generation are used as feedback to the GA to determine the appropriate correction to apply to the mirror. Two MMDMs are used, a 30 x 8 mm, 39 actuator linear MMDM for pulse-shaping applications and a 15 mm diameter, 37 actuator wavefront MMDM. Linear pre-compensation of self-phase modulation (SPM) was experimentally demonstrated utilizing the linear MMDM in a linear pulse-shaper for ultrafast pulses. The nonlinear nature of SPM makes arbitrary polynomial compensation necessary. Pre-compensation of SPM generated in an optical fiber by a 10 fs pulse reduced the pulse from 30fs to 20fs. We demonstrates adaptive correction with the wavefront MMDM by corrected for coma and astigmatism in a reflective multiphoton scanning microscope. An f1, parabola produces a very tight focus with no aberration when it is perfectly aligned. However, when beam scanning is used for two-dimensional imaging the image is severely aberrated. The MMDM and the GA are able to find the best possible wavefront for aberration correction for each scanning position. The horizontal scanning range was increased from 60 mum without the adaptive correction to 170 mum, ≈3 times the uncorrected scanning range, and the vertical scanning range was increased by a comparable amount. This resulted in an increase in scanning area of 9 times. The wavefront MMDM was also used for adaptive correction of spherical aberration from focusing from air, deep into a water-based sample. This depth-based aberration results from an index of refraction mismatch between the sample and the immersion medium of the objective and occurs regardless of beam scanning or sample scanning. By

  5. Improvement of flight simulator feeling using adaptive fuzzy backlash compensation

    Amara, Zied; Bordeneuve-Guibé, Joël

    2007-01-01

    In this paper we addressed the problem of improving the control of DC motors used for the specific application of a 3 degrees of freedom moving base flight simulator. Indeed the presence of backlash in DC motors gearboxes induces shocks and naturally limits the flight feeling. In this paper, dynamic inversion with Fuzzy Logic is used to design an adaptive backlash compensator. The classification property of fuzzy logic techniques makes them a natural candidate for the rejection of errors indu...

  6. Sensorimotor Adaptability Training Improves Motor and Dual-Task Performance

    Bloomberg, J.J.; Peters, B.T.; Mulavara, A.P.; Brady, R.; Batson, C.; Cohen, H.S.

    2009-01-01

    The overall objective of our project is to develop a sensorimotor adaptability (SA) training program designed to facilitate recovery of functional capabilities when astronauts transition to different gravitational environments. The goal of our current study was to determine if SA training using variation in visual flow and support surface motion produces improved performance in a novel sensory environment and demonstrate the retention characteristics of SA training.

  7. Dynamically Adaptable Improved OLSR (DA-IOLSR Protocol

    P.S.Vinayagam,

    2016-05-01

    Full Text Available Optimized Link State Routing (OLSR protocol is a proactive type of routing protocol that uses Multipoint Relay (MPR set as the virtual backbone structure. The existing literature has identified various issues with respect to its backbone structure and has accordingly proposed improvements. In this paper, the focus is on improving the OLSR protocol by employing a Connected Dominating Set (CDS based virtual backbone structure that is dynamically adaptable to rapid topology changes. A new Dynamically Adaptable Improved Optimized Link State Routing (DA-IOLSR protocol is proposed that uses the local topology information to adapt the virtual backbone to topology changes. This assumes significance especially in networks that experience very high mobility. Changes in the network topology caused by node additions, node deletions and node mobility are taken care of. Simulations are carried out to assess the performance of DA-IOLSR protocol and OLSR protocol. Packet delivery achieved by both the protocols is examined under varying mobility by using various combinations of node speed and pause time values. It is found that DA-IOLSR protocol provides better packet delivery as compared to OLSR protocol, under varying mobility conditions.

  8. Designing Training for Temporal and Adaptive Transfer: A Comparative Evaluation of Three Training Methods for Process Control Tasks

    Kluge, Annette; Sauer, Juergen; Burkolter, Dina; Ritzmann, Sandrina

    2010-01-01

    Training in process control environments requires operators to be prepared for temporal and adaptive transfer of skill. Three training methods were compared with regard to their effectiveness in supporting transfer: Drill & Practice (D&P), Error Training (ET), and procedure-based and error heuristics training (PHT). Communication electronics…

  9. Adaptive myoelectric pattern recognition toward improved multifunctional prosthesis control.

    Liu, Jie

    2015-04-01

    The non-stationary property of electromyography (EMG) signals in real life settings usually hinders the clinical application of the myoelectric pattern recognition for prosthesis control. The classical EMG pattern recognition approach consists of two separate steps: training and testing, without considering the changes between training and testing data induced by electrode shift, fatigue, impedance changes and psychological factors, and often results in performance degradation. The aim of this study was to develop an adaptive myoelectric pattern recognition system, aiming to retrain the classifier online with the testing data without supervision, providing a self-correction mechanism for suppressing misclassifications. This paper presents an adaptive unsupervised classifier based on support vector machine (SVM) to improve the classification performance. Experimental data from 15 healthy subjects were used to evaluate performance. Preliminary study on intra-session and inter-session EMG data was conducted to verify the performance of the unsupervised adaptive SVM classifier. The unsupervised adaptive SVM classifier outperformed the conventional SVM by 3.3% and 8.0% for the combination of time-domain and autoregressive features in the intra-session and inter-session tests, respectively. The proposed approach is capable of incorporating the useful information in testing data to the classification model by taking into account the overtime changes in the testing data with respect to the training data to retrain the original classifier, therefore providing a self-correction mechanism for suppressing misclassifications. PMID:25749182

  10. An Improved Adaptive model for Information Recommending and Spreading

    CHEN Duan-Bing; GAO Hui

    2012-01-01

    People in the Internet era have to cope with information overload and expend great effort on finding what they need.Recent experiments indicate that recommendations based on users' past activities are usually less favored than those based on social relationships,and thus many researchers have proposed adaptive algorithms on social recommendation.However,in those methods,quite a number of users have little chance to recommend information,which might prevent valuable information from spreading.We present an improved algorithm that allows more users to have enough followers to spread information.Experimental results demonstrate that both recommendation precision and spreading effectiveness of our method can be improved significantly.%People in the Internet era have to cope with information overload and expend great effort on finding what they need. Recent experiments indicate that recommendations based on users' past activities are usually less favored than those based on social relationships, and thus many researchers have proposed adaptive algorithms on social recommendation. However, in those methods, quite a number of users have little chance to recommend information, which might prevent valuable information from spreading. We present an improved algorithm that allows more users to have enough followers to spread information. Experimental results demonstrate that both recommendation precision and spreading effectiveness of our method can be improved significantly.

  11. Distributed System for Automatic Improvement of Adaptive Website Navigation

    Željko Eremić

    2012-03-01

    Full Text Available Communication with clients is now largely conducted through websites, whether it comes to business, scientific, or educational activities. Considering that a dynamic website contains a growing amount of information, the issue of efficient navigation through websites allowing quick access to desired content is imperative. Adaptive websites can customize their navigation based on knowledge gained from previous user behaviour. Discovering such knowledge is a process that engages significant resources, and it is convenient to have it organized by the use of one or more servers. This paper describes the architecture of distributed systems for improving navigation through a greater number of adaptive websites. High flexibility, efficiency and reliability of the performance, as well as saving user's time and effort, can be obtained as a result of this system's usage.

  12. Development of adaptive optical system of both spatial and temporal beam shaping for UV-laser pulse

    We have been developing a stable and highly qualified UV-laser pulse as a light source of an rf gun for an injector candidate of future light sources. The CPA (chirped pulse amplification) Ti:Sapphire laser system is operated at a repetition rate of 10 Hz. At the third-harmonic generation (central wavelength: 263 nm), the laser pulse energy after a 45-cm silica rod is up to 850 mJ/pulse. In its present status, the laser's pulse energy stability has been improved down to 0.2-0.3% at the fundamental and 0.7-1.4% (rms; 10pps; 33,818 shots) at the third-harmonic generation, respectively. This stability has been held for one month continuously, 24 hours a day. The improvements we had passively implemented were to stabilize the laser system as well as the environmental conditions. We introduced a humidity-control system kept at 50-60% in a clean room to reduce damage to the optics. In addition, we prepared a deformable mirror for spatial shaping and a spatial light modulator based on fused-silica plates for temporal shaping. We are applying both of the adaptive optics to automatic optimization of the electron beam bunch to produce lower emittance with the feedback routine. After the improvements, we can now freely form any arbitrary laser intensity distribution on the surface of the cathode. A fiber bundle was used to passively shape the laser spatial and temporal profile for the backward cathode illumination. The profile was spatially shaped into a perfectly homogeneous one with a 90-cm long fiber bundle. This shaping technique is based in practice on pulse stacking with 1,300 different optical paths. The 80-fs laser is shaped as a quasi-Gaussian profile with a pulse duration of 16 ps (FWHM). Combining with the computer-aided deformable mirror, the fiber bundle laser homogenizer can realize the ideal ellipsoidal laser profile to suppress emittance growing due to the space charge effect. (author)

  13. Adaptive evolution of synthetic cooperating communities improves growth performance.

    Xiaolin Zhang

    Full Text Available Symbiotic interactions between organisms are important for human health and biotechnological applications. Microbial mutualism is a widespread phenomenon and is important in maintaining natural microbial communities. Although cooperative interactions are prevalent in nature, little is known about the processes that allow their initial establishment, govern population dynamics and affect evolutionary processes. To investigate cooperative interactions between bacteria, we constructed, characterized, and adaptively evolved a synthetic community comprised of leucine and lysine Escherichia coli auxotrophs. The co-culture can grow in glucose minimal medium only if the two auxotrophs exchange essential metabolites - lysine and leucine (or its precursors. Our experiments showed that a viable co-culture using these two auxotrophs could be established and adaptively evolved to increase growth rates (by ∼3 fold and optical densities. While independently evolved co-cultures achieved similar improvements in growth, they took different evolutionary trajectories leading to different community compositions. Experiments with individual isolates from these evolved co-cultures showed that changes in both the leucine and lysine auxotrophs improved growth of the co-culture. Interestingly, while evolved isolates increased growth of co-cultures, they exhibited decreased growth in mono-culture (in the presence of leucine or lysine. A genome-scale metabolic model of the co-culture was also constructed and used to investigate the effects of amino acid (leucine or lysine release and uptake rates on growth and composition of the co-culture. When the metabolic model was constrained by the estimated leucine and lysine release rates, the model predictions agreed well with experimental growth rates and composition measurements. While this study and others have focused on cooperative interactions amongst community members, the adaptive evolution of communities with other

  14. GENOMIC APPROACHES FOR IMPROVEMENT OF DROUGHT ADAPTATION IN WHEAT

    Dénes Dudits

    2008-09-01

    Full Text Available Breeding for yield stability under water limited conditions plays an essential role in the reduction of economic and social consequences of global climate changes. We show that two exotic drought resistant genotypes (Kobomughi and Plainsmann differ in root growth rate, root/shoot ratio, and adaptation to low soil water content. These genotypes exhibit characteristic transcript profiles as shown by barley macroarray studies using 10500 unigenes. Reprogramming of gene expression primarily occurred during the 1-2 weeks of water stress, and 6,1% of tested genes were up-regulated in roots of the more adaptive Plainsmann plants. The time course for expression of gene clusters from Kobomughi genotype revealed a prompt and transient gene activation that can help the survival of plants through function of various defense mechanisms. The aldo-keto reductases (AKRs can detoxify lipid peroxidation products (4-hydroxynon-2-enal and glycolysis-derived reactive aldehydes (metylglyoxal that contribute significantly to cellular damages caused by variety of environmental stresses such as drought, high light intensity, UV-B irradiation, cold. Overproduction of AKRs in transgenic tobacco or wheat plants provides considerable stress tolerance and resistance to methylglyoxal. Several transgenic wheat genotypes have been produced with production of elevated level of AKR enzyme. The drought tolerance of these materials was tested by a complex stress diagnostic system, that integrates imaging of plants and monitoring the leaf temperature and fluorescence induction. Based on these parameters, we can conclude that this transgenic strategy that is based on detoxification of lipid aldehyde can result in improved stress adaptation and reduced yield loss.

  15. AN ADAPTIVE REMOTE DISPLAY FRAMEWORK TO IMPROVE POWER EFFICIENCY

    Dong Hyun, Jo

    2015-12-01

    Full Text Available As computing performance and network technology have evolved, mobile device users can enjoy high quality multimedia more easily. Remote Display - the technology which mirrors the screen of one device to another device - allows handheld mobile devices to share their screen contents with larger-sized display devices such as TVs. However, there is general concern about high power consumption caused by complex computation for encoding and continuous data transmission in the mobile devices. In this paper, we present an adaptive remote display framework considering and utilizing the processing capability of display device. By supporting the Content Mirroring Mode, we can skip unnecessary steps and perform core activities to improve power efficiency and extend overall processing capability

  16. ADAPTIVELY IMPROVING LONG DISTANCE NETWORK TRANSFERS WITH LOGISTICS

    LaBissoniere, D.; Roche, K.

    2007-01-01

    Long distance data movement is an essential activity of modern computing. However, the congestion control mechanisms in the Internet’s Transmission Control Protocol (TCP) severely limit the bandwidth achieved by long distance data transfers. The throughput of such transfers can be improved by applying the logistical technique of breaking a single long distance transfer into multiple shorter transfers. This technique can result in signifi cantly improved throughput while still respecting the shared nature of the Internet by not attempting to circumvent the TCP congestion controls. This technique has been incorporated into an algorithm which attempts to dynamically schedule transfers for optimal throughput. The algorithm couples graph techniques with real-time latency and bandwidth measurements to discover the best path and adaptively respond to network dynamics. The algorithm shows improvements in speed and fl exibility over standard data transfer methods such as FTP. Specifi c transfers tests performed between Oak Ridge National Laboratory and a destination in Sunnyvale, CA show throughput increases by a factor of two.

  17. Improving Adaptive Learning Technology through the Use of Response Times

    Mettler, Everett; Massey, Christine M.; Kellman, Philip J.

    2011-01-01

    Adaptive learning techniques have typically scheduled practice using learners' accuracy and item presentation history. We describe an adaptive learning system (Adaptive Response Time Based Sequencing--ARTS) that uses both accuracy and response time (RT) as direct inputs into sequencing. Response times are used to assess learning strength and…

  18. Improved Detection of Time Windows of Brain Responses in Fmri Using Modified Temporal Clustering Analysis

    2002-01-01

    @@ Temporal clustering analysis (TCA) has been proposed recently as a method to detect time windows of brain responses in functional MRI (fMRI) studies when the timing and location of the activation are completely unknown. Modifications to the TCA technique are introduced in this report to further improve the sensitivity in detecting brain activation.

  19. Adaptive data analysis for characterizing the temporal variability of the solar resource

    Bengulescu, Marc; Blanc, Philippe; Wald, Lucien

    2016-01-01

    International audience One of the key challenges associated with the large-scale penetration of solar power is the inherent spatio-temporal variability of the solar radiation impinging on the surface. Particular methods are currently employed to measure, estimate or forecast the extent and availability of the solar resource depending on the effective spatial and temporal scales of interest, such as numerical weather prediction models, satellite-based estimates, sky-imagers or in-situ groun...

  20. An Enhanced Framework for Improving Spatio-Temporal Queries for Global Positioning Systems

    Jalal Atoum

    2013-03-01

    Full Text Available To efficiently process continuous spatio-temporal queries, we need to efficiently and effectively handle large number of moving objects and continuous updates on these queries. In this paper, we propose a framework that employs a new indexing algorithm that is built on top of SQL Server 2008 and avoid the overhead related to R-Tree indexing. To answer range queries, we utilize dynamic materialized view concept to efficiently handle update queries. We propose an adaptive safe region to reduce communication costs between the client and the server and to minimize position update load. Caching of results was utilized to enhance the overall performance of the framework. To handle concurrent spatio-temporal queries, we utilize publish/subscribe paradigm to group similar queries and efficiently process these requests. Experiments show that the overall proposed framework performance was able to outperform R-Tree index and produce promising and satisfactory results

  1. Improving scalable video adaptation in a knowledge-based framework

    Lopez Hernandez, Fernando; Nur, Gokce; Dogan, Safak; Arachchi, Hemantha; Mrak, M.; Martinez, Jose Maria; García Santos, Narciso; Kondoz, Ahmet

    2010-01-01

    In a knowledge-based content adaptation framework, video adaptation can be performed in a series of steps, named conversions. The high-level decision phase in such a framework occasionally encounters several feasible parameter values of a specific conversion. This paper proposes to transfer further decisions to a low-level phase that decides which parameters maximise the quality of the adaptation. Particularly when more than one solution are available, an innovative quality measure is used fo...

  2. Improvement in the performance of solar adaptive optics

    Adaptive optics (AO), which provides diffraction limited imaging over a field-of-view (FOV), is a powerful technique for solar observation. In the tomographic approach, each wavefront sensor (WFS) is looking at a single reference that acts as a guide star. This allows a 3D reconstruction of the distorted wavefront to be made. The correction is applied by one or more deformable mirrors (DMs). This technique benefits from information about atmospheric turbulence at different layers, which can be used to reconstruct the wavefront extremely well. With the assistance of the MAOS software package, we consider the tomography errors and WFS aliasing errors, and focus on how the performance of a solar telescope (pointing toward zenith) is related to atmospheric anisoplanatism. We theoretically quantify the performance of the tomographic solar AO system. The results indicate that the tomographic AO system can improve the average Strehl ratio of a solar telescope in a 10″ – 80″ diameter FOV by only employing one DM conjugated to the telescope pupil. Furthermore, we discuss the effects of DM conjugate altitude on the correction achievable by the AO system by selecting two atmospheric models that differ mainly in terms of atmospheric properties at ground level, and present the optimum DM conjugate altitudes for different observation sites

  3. An Adaptive Organization Method of Geovideo Data for Spatio-Temporal Association Analysis

    Wu, C.; Zhu, Q.; Zhang, Y. T.; Du, Z. Q.; Zhou, Y.; Xie, X.; He, F.

    2015-07-01

    Public security incidents have been increasingly challenging to address with their new features, including large-scale mobility, multi-stage dynamic evolution, spatio-temporal concurrency and uncertainty in the complex urban environment, which require spatio-temporal association analysis among multiple regional video data for global cognition. However, the existing video data organizational methods that view video as a property of the spatial object or position in space dissever the spatio-temporal relationship of scattered video shots captured from multiple video channels, limit the query functions on interactive retrieval between a camera and its video clips and hinder the comprehensive management of event-related scattered video shots. GeoVideo, which maps video frames onto a geographic space, is a new approach to represent the geographic world, promote security monitoring in a spatial perspective and provide a highly feasible solution to this problem. This paper analyzes the large-scale personnel mobility in public safety events and proposes a multi-level, event-related organization method with massive GeoVideo data by spatio-temporal trajectory. This paper designs a unified object identify(ID) structure to implicitly store the spatio-temporal relationship of scattered video clips and support the distributed storage management of massive cases. Finally, the validity and feasibility of this method are demonstrated through suspect tracking experiments.

  4. Temporal perspective and other psychological factors making it difficult to adapt to requirements of treatment in chronic dialysis patients

    Zawadzka, Barbara

    2014-10-01

    Full Text Available Aim. The study analyzed the relationship between temporal perspective, selected personal resources, and unhealthy behavior, manifesting in problems with adherence to fluid intake restrictions, in chronic hemodialyzis patients. The authors tried to answer the question whether there is temporal perspective and other psychological factors increasing the risk of non-adaptive behaviors. Methods. Sixty-one patients, aged 23–81 years (M = 59; SD = 13,9 on chronic hemodialysis at the Department of Nephrology University Hospital were qualified to the study. The study group consisted of 30 patients with poorer fluid regimen adherence and 31 controls, who maintained fluid regimen. The patients were qualified on the bases of the average interdialysis weight gains measured nine times during three weeks. The following research tools were used: P. Zimbardo and J. Boyd ZTPI test; P.T. Costa and R.R. McCrae NEO-FFI Inventory; J. Strelau Temperament Inventory, R. Schwarzer GSES; M. F. Scheier; C. S. Carver and M. W. Bridges LOT-R; M. Watson and S. Greer CECS; BJ. Felton, TA. Revenson, GA. Hinrichsen AIS. Results. Difficulties in adapting to the fluid intake restrictions are significantly associated with temporal orientation towards negative aspects of the present and the past. Non-adaptive health behaviors are typical for patients with temperamental lack of balance between agitation and inhibition processes and are characterized by high agreeableness and low conscientiousness. The association between excessive anger control and the risk of non-adherence medical recommendations. Conclusions. Time perception and other personality factors form mechanisms regulating health behaviors in chronically treatment patients.

  5. Microevolution from shock to adaptation revealed strategies improving ethanol tolerance and production in Thermoanaerobacter

    Lin, Lu; Ji, Yuetong; Tu, Qichao; Huang, Ranran; Teng, Lin; Zeng, Xiaowei; Song, Houhui; Wang, Kun; Zhou, Qian; Li, Yifei; Cui, Qiu; He, Zhili; Zhou, Jizhong; Xu, Jian

    2013-01-01

    Introduction The molecular links between shock-response and adaptation remain poorly understood, particularly for extremophiles. This has hindered rational engineering of solvent tolerance and correlated traits (e.g., productivity) in extremophiles. To untangle such molecular links, here we established a model that tracked the microevolution from shock to adaptation in thermophilic bacteria. Method Temporal dynamics of genomes and transcriptomes was tracked for Thermoanaerobacter sp. X514 whi...

  6. Improvement of the temporal and spatial contrast of high-brightness laser beams

    Szatmári, S.; Dajka, R.; Barna, A.; Gilicze, B.; Földes, I. B.

    2016-07-01

    A novel method is suggested for temporal and spatial cleaning of high-brightness laser pulses, which seems more energy-scalable than that based on crossed polarizers and offers better contrast improvement compared to the plasma mirror technique. The suggested arrangement utilizes nonlinear modulation of the beam in the Fourier-plane leading both to directional and to temporal modulation. By the use of a ‘conjugate’ aperture arrangement before and after the nonlinear spatial selector, intensity dependent transmission is obtained; simultaneous temporal and spatial filtering can be realized both for amplitude and phase modulation. In the case of phase modulation introduced by plasma generation in noble gases the experimental observations are in good agreement with the theory; demonstrating  >103 improvement in the temporal contrast, ~40% throughput, associated with effective spatial filtering. Due to the broad spectral and power durability of the optical arrangement used here, the method is widely applicable for energetic beams even of UV wavelengths, where most of the former techniques have limited throughput.

  7. Advancing of Land Surface Temperature Retrieval Using Extreme Learning Machine and Spatio-Temporal Adaptive Data Fusion Algorithm

    Yang Bai

    2015-04-01

    Full Text Available As a critical variable to characterize the biophysical processes in ecological environment, and as a key indicator in the surface energy balance, evapotranspiration and urban heat islands, Land Surface Temperature (LST retrieved from Thermal Infra-Red (TIR images at both high temporal and spatial resolution is in urgent need. However, due to the limitations of the existing satellite sensors, there is no earth observation which can obtain TIR at detailed spatial- and temporal-resolution simultaneously. Thus, several attempts of image fusion by blending the TIR data from high temporal resolution sensor with data from high spatial resolution sensor have been studied. This paper presents a novel data fusion method by integrating image fusion and spatio-temporal fusion techniques, for deriving LST datasets at 30 m spatial resolution from daily MODIS image and Landsat ETM+ images. The Landsat ETM+ TIR data were firstly enhanced based on extreme learning machine (ELM algorithm using neural network regression model, from 60 m to 30 m resolution. Then, the MODIS LST and enhanced Landsat ETM+ TIR data were fused by Spatio-temporal Adaptive Data Fusion Algorithm for Temperature mapping (SADFAT in order to derive high resolution synthetic data. The synthetic images were evaluated for both testing and simulated satellite images. The average difference (AD and absolute average difference (AAD are smaller than 1.7 K, where the correlation coefficient (CC and root-mean-square error (RMSE are 0.755 and 1.824, respectively, showing that the proposed method enhances the spatial resolution of the predicted LST images and preserves the spectral information at the same time.

  8. Coherent diffractive imaging of time-evolving samples with improved temporal resolution

    Ulvestad, A.; Tripathi, A.; Hruszkewycz, S. O.; Cha, W.; Wild, S. M.; Stephenson, G. B.; Fuoss, P. H.

    2016-05-19

    Bragg coherent x-ray diffractive imaging is a powerful technique for investigating dynamic nanoscale processes in nanoparticles immersed in reactive, realistic environments. Its temporal resolution is limited, however, by the oversampling requirements of three-dimensional phase retrieval. Here, we show that incorporating the entire measurement time series, which is typically a continuous physical process, into phase retrieval allows the oversampling requirement at each time step to be reduced, leading to a subsequent improvement in the temporal resolution by a factor of 2-20 times. The increased time resolution will allow imaging of faster dynamics and of radiation-dose-sensitive samples. This approach, which we call "chrono CDI," may find use in improving the time resolution in other imaging techniques.

  9. Temporal contrast improvement based on the self-diffraction process with a cylinder mirror

    Li, Fangjia; Shen, Xiong; Wang, Peng; Li, Yanyan; Liu, Jun; Wang, Zhanshan; Li, Ruxin

    2016-05-01

    A cylinder reflective mirror was used to increase incident pulse energy to multi-millijoules in the research of temporal contrast enhancement based on a self-diffraction (SD) process. A 170 μJ first-order SD pulse with temporal contrast improved by 4 orders of magnitude was obtained when incident pulse energy was 5.1 mJ. In order to improve energy-conversion efficiency, a 67/33 beam splitter was used to replace the original 50/50 one. A 265 μJ first-order SD signal was achieved without damage of the glass plate at 3.7 mJ input pulse energy with an energy-conversion efficiency of about 7.1%. The generated SD pulse is expected to be used as the seed of high-contrast and high-power laser systems.

  10. Field corn inbreds to improve sweet corn hybrids for early vigor and adaptation to european conditions

    Malvar Pintos, Rosa Ana; Revilla Temiño, Pedro; Cartea González, María Elena; Ordás Pérez, Amando

    1997-01-01

    Sweet corn (Zea mays L.) has a poor adaptation to areas with short growing seasons and cool humid springs, such as the European Atlantic coast. Field corn inbreds adapted to the European Atlantic coast could improve the adaptation of sweet corn to these conditions. Our objectives were to identify field corn inbreds as potentials donors of early vigor and adaptation to the European Atlantic coast, and to provide additional information on the relationships among different estimators of favorabl...

  11. An Improved Adaptive Dynamic Particle Swarm Optimization Algorithm

    Hongbo Zhao; Lina Feng

    2014-01-01

    In order to overcome the weakness that particle swarm optimization algorithm is likely to fall into local minimum when the complex optimization problems are solved, a new adaptive dynamic particle swarm optimization algorithm is proposed. The paper introduces the evaluation index of particle swarm premature convergence to judge the state of particle swarm in the population space, for the sake of investigates the timing of taking effect of influence function. The influence function is adaptive...

  12. Adaptation improves neural coding efficiency despite increasing correlations in variability.

    Adibi, Mehdi; McDonald, James S; Clifford, Colin W G; Arabzadeh, Ehsan

    2013-01-30

    Exposure of cortical cells to sustained sensory stimuli results in changes in the neuronal response function. This phenomenon, known as adaptation, is a common feature across sensory modalities. Here, we quantified the functional effect of adaptation on the ensemble activity of cortical neurons in the rat whisker-barrel system. A multishank array of electrodes was used to allow simultaneous sampling of neuronal activity. We characterized the response of neurons to sinusoidal whisker vibrations of varying amplitude in three states of adaptation. The adaptors produced a systematic rightward shift in the neuronal response function. Consistently, mutual information revealed that peak discrimination performance was not aligned to the adaptor but to test amplitudes 3-9 μm higher. Stimulus presentation reduced single neuron trial-to-trial response variability (captured by Fano factor) and correlations in the population response variability (noise correlation). We found that these two types of variability were inversely proportional to the average firing rate regardless of the adaptation state. Adaptation transferred the neuronal operating regime to lower rates with higher Fano factor and noise correlations. Noise correlations were positive and in the direction of signal, and thus detrimental to coding efficiency. Interestingly, across all population sizes, the net effect of adaptation was to increase the total information despite increasing the noise correlation between neurons. PMID:23365247

  13. Towards Adaptive Educational Assessments: Predicting Student Performance using Temporal Stability and Data Analytics in Learning Management Systems

    Thakur, Gautam [ORNL; Olama, Mohammed M [ORNL; McNair, Wade [ORNL; Sukumar, Sreenivas R [ORNL

    2014-01-01

    Data-driven assessments and adaptive feedback are becoming a cornerstone research in educational data analytics and involve developing methods for exploring the unique types of data that come from the educational context. For example, predicting college student performance is crucial for both the students and educational institutions. It can support timely intervention to prevent students from failing a course, increasing efficacy of advising functions, and improving course completion rate. In this paper, we present our efforts in using data analytics that enable educationists to design novel data-driven assessment and feedback mechanisms. In order to achieve this objective, we investigate temporal stability of students grades and perform predictive analytics on academic data collected from 2009 through 2013 in one of the most commonly used learning management systems, called Moodle. First, we have identified the data features useful for assessments and predicting student outcomes such as students scores in homework assignments, quizzes, exams, in addition to their activities in discussion forums and their total Grade Point Average(GPA) at the same term they enrolled in the course. Second, time series models in both frequency and time domains are applied to characterize the progression as well as overall projections of the grades. In particular, the model analyzed the stability as well as fluctuation of grades among students during the collegiate years (from freshman to senior) and disciplines. Third, Logistic Regression and Neural Network predictive models are used to identify students as early as possible who are in danger of failing the course they are currently enrolled in. These models compute the likelihood of any given student failing (or passing) the current course. The time series analysis indicates that assessments and continuous feedback are critical for freshman and sophomores (even with easy courses) than for seniors, and those assessments may be

  14. Adapting geostatistics to analyze spatial and temporal trends in weed populations

    Geostatistics were originally developed in mining to estimate the location, abundance and quality of ore over large areas from soil samples to optimize future mining efforts. Here, some of these methods were adapted to weeds to account for a limited distribution area (i.e., inside a field), variatio...

  15. Sentence Syntax and Content in the Human Temporal Lobe: An fMRI Adaptation Study in Auditory and Visual Modalities

    Devauchelle, A.D.; Dehaene, S.; Pallier, C. [INSERM, Gif sur Yvette (France); Devauchelle, A.D.; Dehaene, S.; Pallier, C. [CEA, DSV, I2BM, NeuroSpin, F-91191 Gif Sur Yvette (France); Devauchelle, A.D.; Pallier, C. [Univ. Paris 11, Orsay (France); Oppenheim, C. [Univ Paris 05, Ctr Hosp St Anne, Paris (France); Rizzi, L. [Univ Siena, CISCL, I-53100 Siena (Italy); Dehaene, S. [Coll France, F-75231 Paris (France)

    2009-07-01

    Priming effects have been well documented in behavioral psycho-linguistics experiments: The processing of a word or a sentence is typically facilitated when it shares lexico-semantic or syntactic features with a previously encountered stimulus. Here, we used fMRI priming to investigate which brain areas show adaptation to the repetition of a sentence's content or syntax. Participants read or listened to sentences organized in series which could or not share similar syntactic constructions and/or lexico-semantic content. The repetition of lexico-semantic content yielded adaptation in most of the temporal and frontal sentence processing network, both in the visual and the auditory modalities, even when the same lexico-semantic content was expressed using variable syntactic constructions. No fMRI adaptation effect was observed when the same syntactic construction was repeated. Yet behavioral priming was observed at both syntactic and semantic levels in a separate experiment where participants detected sentence endings. We discuss a number of possible explanations for the absence of syntactic priming in the fMRI experiments, including the possibility that the conglomerate of syntactic properties defining 'a construction' is not an actual object assembled during parsing. (authors)

  16. Improving the evidence for ecosystem-based adaptation

    Reid, Hannah

    2011-11-15

    Ecosystem-based approaches to adaptation (EBA) integrate the use of biodiversity and ecosystem services into an overall strategy for helping people adapt to climate change. The body of scientific evidence that indicates how effective they are is in some cases lacking but in other cases is dispersed across a range of related fields, such as natural resource management, disaster risk reduction and agroecology, from which it needs to be synthesised. Without presenting and strengthening this evidence in a consolidated way, EBA cannot secure the policy traction at local, national and international levels that it merits.

  17. Iterative 4D cardiac micro-CT image reconstruction using an adaptive spatio-temporal sparsity prior

    Ritschl, Ludwig; Sawall, Stefan; Knaup, Michael; Hess, Andreas; Kachelrieß, Marc

    2012-03-01

    Temporal-correlated image reconstruction, also known as 4D CT image reconstruction, is a big challenge in computed tomography. The reasons for incorporating the temporal domain into the reconstruction are motions of the scanned object, which would otherwise lead to motion artifacts. The standard method for 4D CT image reconstruction is extracting single motion phases and reconstructing them separately. These reconstructions can suffer from undersampling artifacts due to the low number of used projections in each phase. There are different iterative methods which try to incorporate some a priori knowledge to compensate for these artifacts. In this paper we want to follow this strategy. The cost function we use is a higher dimensional cost function which accounts for the sparseness of the measured signal in the spatial and temporal directions. This leads to the definition of a higher dimensional total variation. The method is validated using in vivo cardiac micro-CT mouse data. Additionally, we compare the results to phase-correlated reconstructions using the FDK algorithm and a total variation constrained reconstruction, where the total variation term is only defined in the spatial domain. The reconstructed datasets show strong improvements in terms of artifact reduction and low-contrast resolution compared to other methods. Thereby the temporal resolution of the reconstructed signal is not affected.

  18. Improving spatial and temporal resolution in evoked EEG responses using surface Laplacians.

    Law, S K; Rohrbaugh, J W; Adams, C M; Eckardt, M J

    1993-01-01

    Spline generated surface Laplacian temporal wave forms are presented as a method to improve both spatial and temporal resolution of evoked EEG responses. Middle latency and the N1 components of the auditory evoked response were used to compare potential-based methods with surface Laplacian methods in the time domain. Results indicate that surface Laplacians provide better estimates of underlying cortical activity than do potential wave forms. Spatial discrimination among electrode sites was markedly better with surface Laplacian than with potential wave forms. Differences in the number and latencies of peaks, and their topographic distributions, were observed for surface Laplacian, particularly during the time period encompassing the middle latency responses. Focal activities were observed in surface Laplacian wave forms and topographic maps which were in agreement with previous findings from auditory evoked response studies. Methodological issues surrounding the application of spline methods to the time domain are also discussed. Surface Laplacian methods in the time domain appear to provide an improved way for studying evoked EEG responses by increasing temporal and spatial resolution of component characteristics. PMID:7688286

  19. Improved proper name recall in aging after electrical stimulation of the anterior temporal lobes

    Lars A Ross

    2011-10-01

    Full Text Available Evidence from neuroimaging and neuropsychology suggests that portions of the anterior temporal lobes play a critical role in proper name retrieval. We previously found that anodal transcranial direct current stimulation (tDCS to the anterior temporal lobes improved retrieval of proper names in young adult. Here we extend that finding to older adults who tend to experience greater proper-naming deficits than young adults. The task was to look at pictures of famous faces or landmarks and verbally recall the associated proper name. Our results show a numerical improvement in face naming after left or right anterior temporal lobe stimulation, but a statistically significant effect only after left-lateralized stimulation. The magnitude of the enhancing effect was similar in older and younger adults but the lateralization of the effect differed depending on age. These results provide evidence that tDCS may be a useful tool for the neurorehabilitation of cognitive function in healthy and pathological cognitive decline.

  20. A phantom study on temporal and subband Minimum Variance adaptive beamforming

    Diamantis, Konstantinos; Voxen, Iben Holfort; Greenaway, Alan H.;

    2014-01-01

    from conventional Delay-and-Sum (DAS) beamformer. FWHM measured at the depth of 46.6 mm, is 0.02 mm (0.09λ) for both adaptive methods while the corresponding values for Hanning and Boxcar weights are 0.64 and 0.44 mm respectively. Between the MV beamformers a -2 dB difference in PSL is noticed in favor...

  1. Improved Gaussian Mixture Models for Adaptive Foreground Segmentation

    Katsarakis, Nikolaos; Pnevmatikakis, Aristodemos; Tan, Zheng-Hua; Prasad, Ramjee

    2016-01-01

    elements to the baseline algorithm: The learning rate can change across space and time, while the Gaussian distributions can be merged together if they become similar due to their adaptation process. We quantify the importance of our enhancements and the effect of parameter tuning using an annotated...

  2. SafeBox: adaptable spatio-temporal generalization for location privacy protection

    Sergio Mascetti

    2014-08-01

    Full Text Available Spatial and temporal generalization emerged in the literature as a common approach to preserve location privacy. However, existing solutions have two main shortcomings. First, spatiotemporal generalization can be used with different objectives: for example, to guarantee anonymity or to decrease the sensitivity of the location information. Hence, the strategy used to compute the generalization can follow different semantics often depending on the privacy threat, while most of the existing solutions are specifically designed for a single semantics. Second, existing techniques prevent the so-called inversion attack by adopting a top-down strategy that needs to acquire a large amount of information. This may not be feasible when this information is dynamic (e.g., position or properties of objects and needs to be acquired from external services (e.g., Google Maps. In this contribution we present a formal model of the problem that is compatible with most of the semantics proposed so far in the literature, and that supports new semantics as well. Our BottomUp algorithm for spatio-temporal generalization is compatible with the use of online services, it supports generalizations based on arbitrary semantics, and it is safe with respect to the inversion attack. By considering two datasets and two examples of semantics, we experimentally compare BottomUp with a more classical top-down algorithm, showing that BottomUp is efficient and guarantees better performance in terms of the average size (space and time of the generalized regions.

  3. Improved Based on "Self-Adaptive Turning Rate" Model Algorithm

    Xiuling He

    2013-06-01

    Full Text Available For tracking the object with tracking nonlinear, high maneuvering target,traditional interactive multiple model self-adaptive filter algorithm was usually adopted.The turning rate estimate was very important. However,the performance of turning rate algorithm was not so satisfactory in the  model.Thus,a new the average value turning rate algorithm based on self-adaptive turning model was proposed.Aiming at additional device for turning rate estimation turning model, the parameters α and β were introduced to adjust the roughness of turning rate.Aiming at target constant turning movement and orthogonal turning rate unequal, estimates, turning rate was used the average value model to reduce the noise and error influence. Simulation results showed that the proposed algorithm was more suitable for the objects with Nonlinear, high maneuvering target tracking and could remarkably reduce the sample,and thus achieve much better tracking performance.

  4. SRAM lifetime improvement by using adaptive proactive reconfiguration

    Pouyan, Peyman; Amat Bertran, Esteve; Rubio Sola, Jose Antonio

    2012-01-01

    Modern generations of CMOS technology nodes are facing critical causes of hardware reliability failures, which were not significant in the past. Such vulnerabilities make it essential to investigate new robust design strategies at the Nanoscale circuit system level. In this paper we have introduced an adaptive proactive reconfiguration technique that considers the inherent process variability (variability-aware) and BTI aging, and effectively enlarges the SRAM lifetime. Peer Reviewed

  5. Adaptive servoventilation improves cardiac function and respiratory stability

    Oldenburg, Olaf; Bitter, Thomas; Lehmann, Roman; Korte, Stefan; Dimitriadis, Zisis; Faber, Lothar; Schmidt, Anke; Westerheide, Nina; Horstkotte, Dieter

    2010-01-01

    Cheyne–Stokes respiration (CSR) in patients with chronic heart failure (CHF) is of major prognostic impact and expresses respiratory instability. Other parameters are daytime pCO2, VE/VCO2-slope during exercise, exertional oscillatory ventilation (EOV), and increased sensitivity of central CO2 receptors. Adaptive servoventilation (ASV) was introduced to specifically treat CSR in CHF. Aim of this study was to investigate ASV effects on CSR, cardiac function, and respiratory stability. A total ...

  6. Spatial and temporal variation of an ice-adapted predator's feeding ecology in a changing Arctic marine ecosystem.

    Yurkowski, David J; Ferguson, Steven H; Semeniuk, Christina A D; Brown, Tanya M; Muir, Derek C G; Fisk, Aaron T

    2016-03-01

    Spatial and temporal variation can confound interpretations of relationships within and between species in terms of diet composition, niche size, and trophic position (TP). The cause of dietary variation within species is commonly an ontogenetic niche shift, which is a key dynamic influencing community structure. We quantified spatial and temporal variations in ringed seal (Pusa hispida) diet, niche size, and TP during ontogeny across the Arctic-a rapidly changing ecosystem. Stable carbon and nitrogen isotope analysis was performed on 558 liver and 630 muscle samples from ringed seals and on likely prey species from five locations ranging from the High to the Low Arctic. A modest ontogenetic diet shift occurred, with adult ringed seals consuming more forage fish (approximately 80 versus 60 %) and having a higher TP than subadults, which generally decreased with latitude. However, the degree of shift varied spatially, with adults in the High Arctic presenting a more restricted niche size and consuming more Arctic cod (Boreogadus saida) than subadults (87 versus 44 %) and adults at the lowest latitude (29 %). The TPs of adult and subadult ringed seals generally decreased with latitude (4.7-3.3), which was mainly driven by greater complexity in trophic structure within the zooplankton communities. Adult isotopic niche size increased over time, likely due to the recent circumpolar increases in subarctic forage fish distribution and abundance. Given the spatial and temporal variability in ringed seal foraging ecology, ringed seals exhibit dietary plasticity as a species, suggesting adaptability in terms of their diet to climate change. PMID:26210748

  7. Development and applications of coherent imaging with improved temporal and spatial resolution

    This work has 2 purposes: the improvement of both temporal and spatial resolution of X-ray tomography. The first part is devoted to the technical aspects of the tomographic technique, particularly at the ESRF (European Synchrotron Radiation Facility) beamline ID19, and the application of the new acquisition scheme to the imaging of liquid foams. We have improved the temporal resolution and field of view of the setup, which allowed to obtain for the first time experimental data with good statistics on three dimensional liquid foams. In the second part of the thesis we have described the Kirkpatrick-Baez focusing system and its first applications. In terms of stability and image quality the developments presented in this part of the thesis provide valuable evidence for the feasibility of phase contrast tomography in magnifying geometry. Since the ultimate goal of this research is to improve the spatial resolution in tomography for applications, four different contributions are important for the characterization of the imaging system: 1) the thermal stability and mechanical imperfections, 2) effects of distortion induced by mirror imperfections, 3) effects of refraction on sample borders, and 4) phase propagation effects with the influence of the magnification. Each of these factors has been studied

  8. Improved adaptive-threshold burst assembly in optical burst switching networks

    Jiuru Yang; Gang Wang; Shilou Jia

    2007-01-01

    An improved adaptive-threshold burst assembly algorithm is proposed to alleviate the limitation of conventional assembly schemes on data loss and delay. The algorithm will adjust the values of assembly factors according to variant traffic regions. And the simulation results show that, by using the adaptive-factor adaptive assembly scheme, the performance of networks is extensively enhanced in terms of burst loss probability and average queuing delay.

  9. Simultaneous expression of regulatory genes associated with specific drought-adaptive traits improves drought adaptation in peanut.

    Ramu, Vemanna S; Swetha, Thavarekere N; Sheela, Shekarappa H; Babitha, Chandrashekar K; Rohini, Sreevathsa; Reddy, Malireddy K; Tuteja, Narendra; Reddy, Chandrashekar P; Prasad, Trichi Ganesh; Udayakumar, Makarla

    2016-03-01

    Adaptation of crops to drought-prone rain-fed conditions can be achieved by improving plant traits such as efficient water mining (by superior root characters) and cellular-level tolerance mechanisms. Pyramiding these drought-adaptive traits by simultaneous expression of genes regulating drought-adaptive mechanisms has phenomenal relevance in improving stress tolerance. In this study, we provide evidence that peanut transgenic plants expressing Alfalfa zinc finger 1 (Alfin1), a root growth-associated transcription factor gene, Pennisetum glaucum heat-shock factor (PgHSF4) and Pea DNA helicase (PDH45) involved in protein turnover and protection showed improved tolerance, higher growth and productivity under drought stress conditions. Stable integration of all the transgenes was noticed in transgenic lines. The transgenic lines showed higher root growth, cooler crop canopy air temperature difference (less CCATD) and higher relative water content (RWC) under drought stress. Low proline levels in transgenic lines substantiate the maintenance of higher water status. The survival and recovery of transgenic lines was significantly higher under gradual moisture stress conditions with higher biomass. Transgenic lines also showed significant tolerance to ethrel-induced senescence and methyl viologen-induced oxidative stress. Several stress-responsive genes such as heat-shock proteins (HSPs), RING box protein-1 (RBX1), Aldose reductase, late embryogenesis abundant-5 (LEA5) and proline-rich protein-2 (PRP2), a gene involved in root growth, showed enhanced expression under stress in transgenic lines. Thus, the simultaneous expression of regulatory genes contributing for drought-adaptive traits can improve crop adaptation and productivity under water-limited conditions. PMID:26383697

  10. SOAR Adaptive Module (SAM): seeing improvement with a UV laser

    Tokovinin, Andrei; Tighe, Roberto; Schurter, Patricio; Martinez, Manuel; Thomas, Sandrine; van der Bliek, Nicole

    2016-01-01

    The adaptive module of the 4.1-m SOAR telescope, SAM, corrects ground-layer turbulence using a UV laser guide star. It has been commissioned in 2013 and it is in regular science operation since 2014. SAM works with the CCD imager covering a 3' field or with the speckle camera. It operates routinely and stably, delivering resolution in the I band equal to the free-atmosphere seeing. This paper describes the SAM system as a whole, providing essential reference for its users and technical information of interest to instrumentalists. Operation of the instrument, its performance, and science projects done with SAM so far are reviewed.

  11. Adaptive optics for improved retinal surgery and diagnostics

    Humayun, M S; Sadda, S R; Thompson, C A; Olivier, S S; Kartz, M W

    2000-08-21

    It is now possible to field a compact adaptive optics (AO) system on a surgical microscope for use in retinal diagnostics and surgery. Recent developments in integrated circuit technology and optical photonics have led to the capability of building an AO system that is compact and significantly less expensive than traditional AO systems. It is foreseen that such an AO system can be integrated into a surgical microscope while maintaining a package size of a lunchbox. A prototype device can be developed in a manner that lends itself well to large-scale manufacturing.

  12. An Improved Adaptive Deconvolution Algorithm for Single Image Deblurring

    Hsin-Che Tsai

    2014-01-01

    Full Text Available One of the most common defects in digital photography is motion blur caused by camera shake. Shift-invariant motion blur can be modeled as a convolution of the true latent image and a point spread function (PSF with additive noise. The goal of image deconvolution is to reconstruct a latent image from a degraded image. However, ringing is inevitable artifacts arising in the deconvolution stage. To suppress undesirable artifacts, regularization based methods have been proposed using natural image priors to overcome the ill-posedness of deconvolution problem. When the estimated PSF is erroneous to some extent or the PSF size is large, conventional regularization to reduce ringing would lead to loss of image details. This paper focuses on the nonblind deconvolution by adaptive regularization which preserves image details, while suppressing ringing artifacts. The way is to control the regularization weight adaptively according to the image local characteristics. We adopt elaborated reference maps that indicate the edge strength so that textured and smooth regions can be distinguished. Then we impose an appropriate constraint on the optimization process. The experiments’ results on both synthesized and real images show that our method can restore latent image with much fewer ringing and favors the sharp edges.

  13. Short-term memory trace in rapidly adapting synapses of inferior temporal cortex.

    Yasuko Sugase-Miyamoto

    2008-05-01

    Full Text Available Visual short-term memory tasks depend upon both the inferior temporal cortex (ITC and the prefrontal cortex (PFC. Activity in some neurons persists after the first (sample stimulus is shown. This delay-period activity has been proposed as an important mechanism for working memory. In ITC neurons, intervening (nonmatching stimuli wipe out the delay-period activity; hence, the role of ITC in memory must depend upon a different mechanism. Here, we look for a possible mechanism by contrasting memory effects in two architectonically different parts of ITC: area TE and the perirhinal cortex. We found that a large proportion (80% of stimulus-selective neurons in area TE of macaque ITCs exhibit a memory effect during the stimulus interval. During a sequential delayed matching-to-sample task (DMS, the noise in the neuronal response to the test image was correlated with the noise in the neuronal response to the sample image. Neurons in perirhinal cortex did not show this correlation. These results led us to hypothesize that area TE contributes to short-term memory by acting as a matched filter. When the sample image appears, each TE neuron captures a static copy of its inputs by rapidly adjusting its synaptic weights to match the strength of their individual inputs. Input signals from subsequent images are multiplied by those synaptic weights, thereby computing a measure of the correlation between the past and present inputs. The total activity in area TE is sufficient to quantify the similarity between the two images. This matched filter theory provides an explanation of what is remembered, where the trace is stored, and how comparison is done across time, all without requiring delay period activity. Simulations of a matched filter model match the experimental results, suggesting that area TE neurons store a synaptic memory trace during short-term visual memory.

  14. Improving personality facet scores with multidimensional computer adaptive testing

    Makransky, Guido; Mortensen, Erik Lykke; Glas, Cees A W

    2013-01-01

    Narrowly defined personality facet scores are commonly reported and used for making decisions in clinical and organizational settings. Although these facets are typically related, scoring is usually carried out for a single facet at a time. This method can be ineffective and time consuming when...... personality tests contain many highly correlated facets. This article investigates the possibility of increasing the precision of the NEO PI-R facet scores by scoring items with multidimensional item response theory and by efficiently administering and scoring items with multidimensional computer adaptive...... testing (MCAT). The increase in the precision of personality facet scores is obtained from exploiting the correlations between the facets. Results indicate that the NEO PI-R could be substantially shorter without attenuating precision when the MCAT methodology is used. Furthermore, the study shows...

  15. Improved adaptive fuzzy control for MIMO nonlinear time-delay systems

    2011-01-01

    This paper presents an improved observer-based indirect adaptive fuzzy control scheme for multiinput-multioutput (MIMO) nonlinear time-delay systems.The control scheme synthesizes adaptive fuzzy control with adaptive fuzzy identification.An observer is designed to observe the system state,and an identifier is developed to identify the unknown parts of the system.The update laws for parameters utilize two types of errors in the adaptive time-delay fuzzy logic systems,the observation error and the identificat...

  16. Improving the Stability of the LMF Adaptive Algorithm Using the Median Filteer

    Bysted, Tommy Kristensen; Rusu, Corneliu

    The stability of the LMF (Least Mean Fourth) adaptive algorithm is improved by using the median of the gradient instead of the raw gradient for updating the coefficients of the adaptive filter. This operation has two advantages: first it improves the performance of the LMF in impulse noise...... environments and secondly it enables the use of larger step-size of the adaptive algorithm especially when the signals are corrupted by noise. The disadvantages are a small raise in the computational complexity and slower convergence than the LMF. Two examples are given which illustrates the behavior of the...

  17. Adapting Job Analysis Methodology to Improve Evaluation Practice

    Jenkins, Susan M.; Curtin, Patrick

    2006-01-01

    This article describes how job analysis, a method commonly used in personnel research and organizational psychology, provides a systematic method for documenting program staffing and service delivery that can improve evaluators' knowledge about program operations. Job analysis data can be used to increase evaluators' insight into how staffs…

  18. Improved two-photon imaging of living neurons in brain tissue through temporal gating.

    Gautam, Vini; Drury, Jack; Choy, Julian M C; Stricker, Christian; Bachor, Hans-A; Daria, Vincent R

    2015-10-01

    We optimize two-photon imaging of living neurons in brain tissue by temporally gating an incident laser to reduce the photon flux while optimizing the maximum fluorescence signal from the acquired images. Temporal gating produces a bunch of ~10 femtosecond pulses and the fluorescence signal is improved by increasing the bunch-pulse energy. Gating is achieved using an acousto-optic modulator with a variable gating frequency determined as integral multiples of the imaging sampling frequency. We hypothesize that reducing the photon flux minimizes the photo-damage to the cells. Our results, however, show that despite producing a high fluorescence signal, cell viability is compromised when the gating and sampling frequencies are equal (or effectively one bunch-pulse per pixel). We found an optimum gating frequency range that maintains the viability of the cells while preserving a pre-set fluorescence signal of the acquired two-photon images. The neurons are imaged while under whole-cell patch, and the cell viability is monitored as a change in the membrane's input resistance. PMID:26504651

  19. Temporal Adaptive Changes in Contractility and Fatigability of Diaphragm Muscles from Streptozotocin-Diabetic Rats

    Marco Brotto

    2010-01-01

    Full Text Available Diabetes is characterized by ventilatory depression due to decreased diaphragm (DPH function. This study investigated the changes in contractile properties of rat DPH muscles over a time interval encompassing from 4 days to 14 weeks after the onset of streptozotocin-induced diabetes, with and without insulin treatment for 2 weeks. Maximum tetanic force in intact DPH muscle strips and recovery from fatiguing stimulation were measured. An early (4-day depression in contractile function in diabetic DPH was followed by gradual improvement in muscle function and fatigue recovery (8 weeks. DPH contractile function deteriorated again at 14 weeks, a process that was completely reversed by insulin treatment. Maximal contractile force and calcium sensitivity assessed in Triton-skinned DPH fibers showed a similar bimodal pattern and the same beneficial effect of insulin treatment. While an extensive analysis of the isoforms of the contractile and regulatory proteins was not conducted, Western blot analysis of tropomyosin suggests that the changes in diabetic DPH response depended, at least in part, on a switch in fiber type.

  20. Adapting and using quality management methods to improve health promotion.

    Becker, Craig M; Glascoff, Mary A; Felts, William Michael; Kent, Christopher

    2015-01-01

    Although the western world is the most technologically advanced civilization to date, it is also the most addicted, obese, medicated, and in-debt adult population in history. Experts had predicted that the 21st century would be a time of better health and prosperity. Although wealth has increased, our quest to quell health problems using a pathogenic approach without understanding the interconnectedness of everyone and everything has damaged personal and planetary health. While current efforts help identify and eliminate causes of problems, they do not facilitate the creation of health and well-being as would be done with a salutogenic approach. Sociologist Aaron Antonovsky coined the term salutogenesis in 1979. It is derived from salus, which is Latin for health, and genesis, meaning to give birth. Salutogenesis, the study of the origins and creation of health, provides a method to identify an interconnected way to enhance well-being. Salutogenesis provides a framework for a method of practice to improve health promotion efforts. This article illustrates how quality management methods can be used to guide health promotion efforts focused on improving health beyond the absence of disease. PMID:25777291

  1. Improved Efficacy of Temporally Non-Regular Deep Brain Stimulation in Parkinson's Disease

    Brocker, David T.; Swan, Brandon D; Turner, Dennis A.; Gross, Robert E.; Tatter, Stephen B.; Koop, Mandy Miller; Bronte-Stewart, Helen; Grill, Warren M.

    2012-01-01

    High frequency deep brain stimulation is an effective therapy for motor symptoms in Parkinson's disease. However, the relative clinical efficacy of regular versus non-regular temporal patterns of stimulation in Parkinson's disease remains unclear. To determine the temporal characteristics of non-regular temporal patterns of stimulation important for treatment of Parkinson's disease, we compared the efficacy of temporally regular stimulation with four non-regular patterns of stimulation in sub...

  2. Adaptation AC to Improve Wireless Access Network Dependability

    Olfa BEN AHMED

    2012-01-01

    Full Text Available According to estimation of increasing mobile application‘s consumers. We are interested in Long TermEvaluation (LTE network. LTE dependability depends on availability and reliability of his evolved NodesBases stations (eNB. One eNB is available when it is able yet to admit a new media and to supportconnection. And it is reliable when it is able to support handover connection. However we consider adependable telecommunication service when the available and reliable system can provide an acceptablequality of service (QoS. There are works that given a higher QoS with lower dependability (availabilityand reliability and works that given higher dependability with lowest QoS. We propose a new AdmissionControl scheme using preemption bandwidth from already connected application. Our preemptionproceeds in a relative utility. Results of this work give improvement of dependability with acceptable QoS.

  3. Adaptive noise estimation and suppression for improving microseismic event detection

    Mousavi, S. Mostafa; Langston, Charles A.

    2016-09-01

    Microseismic data recorded by surface arrays are often strongly contaminated by unwanted noise. This background noise makes the detection of small magnitude events difficult. A noise level estimation and noise reduction algorithm is presented for microseismic data analysis based upon minimally controlled recursive averaging and neighborhood shrinkage estimators. The method might not be compared with more sophisticated and computationally expensive denoising algorithm in terms of preserving detailed features of seismic signal. However, it is fast and data-driven and can be applied in real-time processing of continuous data for event detection purposes. Results from application of this algorithm to synthetic and real seismic data show that it holds a great promise for improving microseismic event detection.

  4. Improve Problem Solving Skills through Adapting Programming Tools

    Shaykhian, Linda H.; Shaykhian, Gholam Ali

    2007-01-01

    There are numerous ways for engineers and students to become better problem-solvers. The use of command line and visual programming tools can help to model a problem and formulate a solution through visualization. The analysis of problem attributes and constraints provide insight into the scope and complexity of the problem. The visualization aspect of the problem-solving approach tends to make students and engineers more systematic in their thought process and help them catch errors before proceeding too far in the wrong direction. The problem-solver identifies and defines important terms, variables, rules, and procedures required for solving a problem. Every step required to construct the problem solution can be defined in program commands that produce intermediate output. This paper advocates improved problem solving skills through using a programming tool. MatLab created by MathWorks, is an interactive numerical computing environment and programming language. It is a matrix-based system that easily lends itself to matrix manipulation, and plotting of functions and data. MatLab can be used as an interactive command line or a sequence of commands that can be saved in a file as a script or named functions. Prior programming experience is not required to use MatLab commands. The GNU Octave, part of the GNU project, a free computer program for performing numerical computations, is comparable to MatLab. MatLab visual and command programming are presented here.

  5. Improving GPU-accelerated Adaptive IDW Interpolation Algorithm Using Fast kNN Search

    Mei, Gang; Xu, Nengxiong; Xu, Liangliang

    2016-01-01

    This paper presents an efficient parallel Adaptive Inverse Distance Weighting (AIDW) interpolation algorithm on modern Graphics Processing Unit (GPU). The presented algorithm is an improvement of our previous GPU-accelerated AIDW algorithm by adopting fast k-Nearest Neighbors (kNN) search. In AIDW, it needs to find several nearest neighboring data points for each interpolated point to adaptively determine the power parameter; and then the desired prediction value of the interpolated point is ...

  6. A self-adaptive step Cuckoo search algorithm based on dimension by dimension improvement

    Ren, Lu; Li, Haiyang; He, Xingshi

    2015-01-01

    The choice of step length plays an important role in convergence speed and precision of Cuckoo search algorithm. In the paper, a self-adaptive step Cuckoo search algorithm based on dimensional improvement is provided. First, since the step in the original self-adaptive step Cuckoo search algorithm is not updated when the current position of the nest is in the optimal position, simple modification of the step is made for the update. Second, evaluation strategy based on dimension by dimension u...

  7. Adaptive shaping system for both spatial and temporal profiles of a highly stabilized UV laser light source for a photocathode RF gun

    We have been developing a stable and highly qualified ultraviolet (UV) laser pulse as a light source of an RF gun for an injector candidate of future light sources. Our gun cavity is a single-cell pillbox, and the copper inner wall is used as a photocathode. The chirped pulse amplification (CPA) Ti:sapphire laser system is operated at a repetition rate of 10 Hz. At the third harmonic generation (central wavelength-263 nm), the laser pulse energy after a 45 cm silica rod is up to 850 μJ/pulse. In its present status, the laser's pulse energy stability has been improved down to 0.2∼0.3% at the fundamental, and 0.7-1.4% (rms; 10 pps; 33,818 shots) at the third harmonic generation, respectively. This stability has been held for 1 month continuously, 24 h a day. The improvements we had passively implemented were to stabilize the laser system as well as the environmental conditions. We introduced a humidity-control system kept at 50-60% in a clean room to reduce damage to the optics. In addition, we prepared a deformable mirror for spatial shaping and a spatial light modulator based on fused-silica plates for temporal shaping. We are applying both the adaptive optics to automatic optimization of the electron beam bunch to produce lower emittance with the feedback routine. Before the improvements, the electron beam produced from a cathode suffered inhomogeneous distribution caused by the quantum efficiency effect, and some pulse distortions caused by its response time. However, we can now freely form any arbitrary electron beam distribution on the surface of the cathode

  8. C-arm cone beam CT perfusion imaging using the SMART-RECON algorithm to improve temporal sampling density and temporal resolution

    Li, Yinsheng; Niu, Kai; Li, Ke; Schafer, Sebastian; Royalty, Kevin; Strother, Charles; Chen, Guang-Hong

    2016-03-01

    In this work, a newly developed reconstruction algorithm, Synchronized MultiArtifact Reduction with Tomographic RECONstruction (SMART-RECON), was applied to C-arm cone beam CT perfusion (CBCTP) imaging. This algorithm contains a special rank regularizer, designed to reduce limited-view artifacts associated with super- short scan reconstructions. As a result, high temporal sampling and temporal resolution image reconstructions were achieved using an interventional C-arm x-ray system. The algorithm was evaluated in terms of the fidelity of the dynamic contrast update curves and the accuracy of perfusion parameters through numerical simulation studies. Results shows that, not only were the dynamic curves accurately recovered (relative root mean square error ∈ [3%, 5%] compared with [13%, 22%] for FBP), but also the noise in the final perfusion maps was dramatically reduced. Compared with filtered backprojection, SMART-RECON generated CBCTP maps with much improved capability in differentiating lesions with perfusion deficits from the surrounding healthy brain tissues.

  9. Utilizing temporal variations in chemotherapeutic response to improve breast cancer treatment efficacy

    Daniel J. McGrail

    2015-09-01

    Full Text Available Though survival rates for women with stage I breast cancer have radically improved, treatment options remain poor for the 40% of women diagnosed with later-stage disease. For these patients, improved chemotherapeutic treatment strategies are critical to eradicate any disseminated tumor cells. Despite many promising new drugs in vitro, most ultimately fail in the clinic. One aspect often lost during testing is in vivo circulation half-lives rarely exceed 24 hours, whereas in vitro studies involve drug exposure for 2-3 days. Here, we show how mimicking these exposure times alters efficacy. Next, using this model we show how drug response is highly time-dependent by extending analysis of cell viability out to two weeks. Variations in response both with feeding and time were dependent on drug mechanism of action. Finally, we show that by implementing this temporal knowledge of drug effects to optimize scheduling of drug administration we are able to regain chemosensitivity in a Carboplatin-resistant cell line.

  10. Long-term effective population sizes, temporal stability of genetic composition and potential for local adaptation in anadromous brown trout ( Salmo trutta ) populations

    Hansen, Michael Møller; Ruzzante, D.E.; Eg Nielsen, Einar; Bekkevold, Dorte; Mensberg, Karen-Lise Dons

    2002-01-01

    We examined the long-term temporal (1910s to 1990s) genetic variation at eight microsatellite DNA loci in brown trout (Salmo trutta L) collected from five anadromous populations in Denmark to assess the long-term stability of genetic composition and to estimate effective population sizes (N...... (3 km) river showed Ne greater than or equal to 300. Assuming a stepping-stone model of gene flow we considered the relative roles of gene flow, random genetic drift and selection to assess the possibilities for local adaptation. The requirements for local adaptation were fulfilled, but only...... adaptations resulting from strong selection were expected to occur at the level of individual populations. Adaptations resulting from weak selection were more likely to occur on a regional basis, i.e. encompassing several populations. N-e appears to have declined recently in at least one of the studied...

  11. Habitat Choice and Temporal Variation Alter the Balance between Adaptation by Genetic Differentiation, a Jack-of-All-Trades Strategy, and Phenotypic Plasticity.

    Scheiner, Samuel M

    2016-05-01

    Confronted with variable environments, species adapt in several ways, including genetic differentiation, a jack-of-all-trades strategy, or phenotypic plasticity. Adaptive habitat choice favors genetic differentiation and local adaptation over a generalist, jack-of-all-trades strategy. Models predict that, absent plasticity costs, variable environments generally favor phenotypic plasticity over genetic differentiation and being a jack-of-all-trades generalist. It is unknown how habitat choice might affect the evolution of plasticity. Using an individual-based simulation model, I explored the interaction of choice and plasticity. With only spatial variation, habitat choice promotes genetic differentiation over a jack-of-all-trades strategy or phenotypic plasticity. In the absence of plasticity, temporal variation favors a jack-of-all-trades strategy over choice-mediated genetic differentiation; when plasticity is an option, it is favored. This occurs because habitat choice creates a feedback between genetic differentiation and dispersal rates. As demes become better adapted to their local environments, the effective dispersal rate decreases, because more individuals have very high fitness and so choose not to disperse, reinforcing local stabilizing selection and negating selection for plasticity. Temporal variation breaks that feedback. These results point to a potential data paradox: systems with habitat choice may have the lowest actual movement rates. The potential for adaptive habitat choice may be very common, but its existence may reduce observed dispersal rates enough that we do not recognize systems where it may be present, warranting further exploration of likely systems. PMID:27104995

  12. Research on Public Traffic Vehicles Dispatch Based on Improved Adaptive Genetic Algorithm

    2010-01-01

    <正>Bus dispatching has been studied,and also the bus dispatching model is set up.Then,Genetic Algorithm is adaptively improved in order to avoid premature problem and the slow convergence,and then the keeping optimal strategy is used to the Genetic Algorithm,so formed the Improved Adaptive Genetic Algorithm,namely IAGA. Finally,the IAGA is used to optimizing the bus dispatching model,and the results of the simulation indicate IAGA has the higher efficiency than simple GA and is one effective way to optimizing the bus dispatching.

  13. Delay Estimator and Improved Proportionate Multi-Delay Adaptive Filtering Algorithm

    E. Verteletskaya

    2012-04-01

    Full Text Available This paper pertains to speech and acoustic signal processing, and particularly to a determination of echo path delay and operation of echo cancellers. To cancel long echoes, the number of weights in a conventional adaptive filter must be large. The length of the adaptive filter will directly affect both the degree of accuracy and the convergence speed of the adaptation process. We present a new adaptive structure which is capable to deal with multiple dispersive echo paths. An adaptive filter according to the present invention includes means for storing an impulse response in a memory, the impulse response being indicative of the characteristics of a transmission line. It also includes a delay estimator for detecting ranges of samples within the impulse response having relatively large distribution of echo energy. These ranges of samples are being indicative of echoes on the transmission line. An adaptive filter has a plurality of weighted taps, each of the weighted taps having an associated tap weight value. A tap allocation/control circuit establishes the tap weight values in response to said detecting means so that only taps within the regions of relatively large distributions of echo energy are turned on. Thus, the convergence speed and the degree of estimation in the adaptation process can be improved.

  14. Long-term effective population sizes, temporal stability of genetic composition and potential for local adaptation in anadromous brown trout ( Salmo trutta ) populations

    Hansen, Michael Møller; Ruzzante, D.E.; Eg Nielsen, Einar;

    2002-01-01

    We examined the long-term temporal (1910s to 1990s) genetic variation at eight microsatellite DNA loci in brown trout (Salmo trutta L) collected from five anadromous populations in Denmark to assess the long-term stability of genetic composition and to estimate effective population sizes (N...... populations, and the documented recent declines of many other anadromous brown trout populations may affect the persistence of local adaptation....

  15. Improving Prediction Accuracy for WSN Data Reduction by Applying Multivariate Spatio-Temporal Correlation

    José Neuman de Souza

    2011-10-01

    Full Text Available This paper proposes a method based on multivariate spatial and temporal correlation to improve prediction accuracy in data reduction for Wireless Sensor Networks (WSN. Prediction of data not sent to the sink node is a technique used to save energy in WSNs by reducing the amount of data traffic. However, it may not be very accurate. Simulations were made involving simple linear regression and multiple linear regression functions to assess the performance of the proposed method. The results show a higher correlation between gathered inputs when compared to time, which is an independent variable widely used for prediction and forecasting. Prediction accuracy is lower when simple linear regression is used, whereas multiple linear regression is the most accurate one. In addition to that, our proposal outperforms some current solutions by about 50% in humidity prediction and 21% in light prediction. To the best of our knowledge, we believe that we are probably the first to address prediction based on multivariate correlation for WSN data reduction.

  16. Plant functional traits improve diversity-based predictions of temporal stability of grassland productivity

    Aboveground net primary productivity (ANPP) varies in response to temporal fluctuations in weather. Temporal stability (mean/standard deviation) of community ANPP may be increased, on average, by increasing plant species richness, but stability also may differ widely at a given richness level imply...

  17. Improving spatio-temporal resolution of infrared images to detect thermal activity of defect at the surface of inorganic glass

    Corvec, Guillaume; Robin, Eric; Le Cam, Jean-Benoît; Sangleboeuf, Jean-Christophe; Lucas, Pierre

    2016-07-01

    This paper proposes a noise suppression methodology to improve the spatio-temporal resolution of infrared images. The methodology is divided in two steps. The first one consists in removing the noise from the temporal signal at each pixel. Three basic temporal filters are considered for this purpose: average filter, cost function minimization (FIT) and short time Fast Fourier Transform approach (STFFT). But while this step effectively reduces the temporal signal noise at each pixel, the infrared images may still appear noisy. This is due to a random distribution of a residual offset value of pixels signal. Hence in the second step, the residual offset is identified by considering thermal images for which no mechanical loading is applied. In this case, the temperature variation field is homogeneous and the value of temperature variation at each pixel is theoretically equal to zero. The method is first tested on synthetic images built from infrared computer-generated images combined with experimental noise. The results demonstrate that this approach permits to keep the spatial resolution of infrared images equal to 1 pixel. The methodology is then applied to characterize thermal activity of a defect at the surface of inorganic glass submitted to cyclic mechanical loading. The three basic temporal filters are quantitatively compared and contrasted. Results obtained demonstrate that, contrarily to a basic spatio-temporal approach, the denoising method proposed is suitable to characterize low thermal activity combined to strong spatial gradients induced by cyclic heterogeneous deformations.

  18. Effects of improved spatial and temporal modeling of on-road vehicle emissions.

    Lindhjem, Christian E; Pollack, Alison K; DenBleyker, Allison; Shaw, Stephanie L

    2012-04-01

    Numerous emission and air quality modeling studies have suggested the need to accurately characterize the spatial and temporal variations in on-road vehicle emissions. The purpose of this study was to quantify the impact that using detailed traffic activity data has on emission estimates used to model air quality impacts. The on-road vehicle emissions are estimated by multiplying the vehicle miles traveled (VMT) by the fleet-average emission factors determined by road link and hour of day. Changes in the fraction of VMT from heavy-duty diesel vehicles (HDDVs) can have a significant impact on estimated fleet-average emissions because the emission factors for HDDV nitrogen oxides (NOx) and particulate matter (PM) are much higher than those for light-duty gas vehicles (LDGVs). Through detailed road link-level on-road vehicle emission modeling, this work investigated two scenarios for better characterizing mobile source emissions: (1) improved spatial and temporal variation of vehicle type fractions, and (2) use of Motor Vehicle Emission Simulator (MOVES2010) instead of MOBILE6 exhaust emission factors. Emissions were estimated for the Detroit and Atlanta metropolitan areas for summer and winter episodes. The VMT mix scenario demonstrated the importance of better characterizing HDDV activity by time of day, day of week, and road type. More HDDV activity occurs on restricted access road types on weekdays and at nonpeak times, compared to light-duty vehicles, resulting in 5-15% higher NOx and PM emission rates during the weekdays and 15-40% lower rates on weekend days. Use of MOVES2010 exhaust emission factors resulted in increases of more than 50% in NOx and PM for both HDDVs and LDGVs, relative to MOBILE6. Because LDGV PM emissions have been shown to increase with lower temperatures, the most dramatic increase from MOBILE6 to MOVES2010 emission rates occurred for PM2.5 from LDGVs that increased 500% during colder wintertime conditions found in Detroit, the northernmost

  19. Adapt

    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

  20. Improving the adaptability of simulated evolutionary swarm robots in dynamically changing environments.

    Yao Yao

    Full Text Available One of the important challenges in the field of evolutionary robotics is the development of systems that can adapt to a changing environment. However, the ability to adapt to unknown and fluctuating environments is not straightforward. Here, we explore the adaptive potential of simulated swarm robots that contain a genomic encoding of a bio-inspired gene regulatory network (GRN. An artificial genome is combined with a flexible agent-based system, representing the activated part of the regulatory network that transduces environmental cues into phenotypic behaviour. Using an artificial life simulation framework that mimics a dynamically changing environment, we show that separating the static from the conditionally active part of the network contributes to a better adaptive behaviour. Furthermore, in contrast with most hitherto developed ANN-based systems that need to re-optimize their complete controller network from scratch each time they are subjected to novel conditions, our system uses its genome to store GRNs whose performance was optimized under a particular environmental condition for a sufficiently long time. When subjected to a new environment, the previous condition-specific GRN might become inactivated, but remains present. This ability to store 'good behaviour' and to disconnect it from the novel rewiring that is essential under a new condition allows faster re-adaptation if any of the previously observed environmental conditions is reencountered. As we show here, applying these evolutionary-based principles leads to accelerated and improved adaptive evolution in a non-stable environment.

  1. An improved Direct Adaptive Fuzzy controller for an uncertain DC Motor Speed Control System

    Chunjie Zhou; Shuang Huang; Quan Yin; Duc Cuong Quach

    2013-01-01

    In this paper, we present an improved Direct Adaptive Fuzzy (IDAF) controller applied to general control DC motor speed system. In particular, an IDAF algorithm is designed to control an uncertain DC motor speed to track a given reference signal. In fact, the quality of the control system depends significantly on the amount of fuzzy rules-fuzzy sets and the updating coefficient of the adaptive rule. This can be observed clearly by the system error when the reference input is constant and out ...

  2. A rate adaptive control method for Improving the imaging speed of atomic force microscopy

    A simple rate adaptive control method is proposed to improve the imaging speed of the atomic force microscope (AFM) in the paper. Conventionally, the probe implemented on the AFM scans the sample surface at a constant rate, resulting in low time efficiency. Numerous attempts have been made to realize high-speed AFMs, while little efforts are put into changing the constant-rate scanning. Here we report a rate adaptive control method based on variable-rate scanning. The method automatically sets the imaging speed for the x scanner through the analysis of the tracking errors in the z direction at each scanning point, thus improving the dynamic tracking performance of the z scanner. The development and functioning of the rate adaptive method are demonstrated, as well as how the approach significantly achieves faster scans and a higher resolution AFM imaging. - Highlights: • A rate adaptive control method is proposed to improve the imaging speed ofAFM. • The new method automatically selects appropriate scanning speed in the x direction through the analysis of the tracking errors in the z direction. • The system identification is carried out to obtain the mathematical model of thevertical feedback system of AFM

  3. Adaptation to climate change in industry: improving resource efficiency through sustainable production applications.

    Alkayal, Emrah; Bogurcu, Merve; Ulutas, Ferda; Demirer, Göksel Niyazi

    2015-01-01

    The objective of this study was to investigate the climate change adaptation opportunities of six companies from different sectors through resource efficiency and sustainable production. A total of 77 sustainable production options were developed for the companies based on the audits conducted. After screening these opportunities with each company's staff, 19 options were selected and implemented. Significant water savings (849,668 m3/year) were achieved as a result of the applications that targeted reduction of water use. In addition to water savings, the energy consumption was reduced by 3,607 MWh, which decreased the CO2 emissions by 904.1 tons/year. Moreover, the consumption of 278.4 tons/year of chemicals (e.g., NaCl, CdO, NaCN) was avoided, thus the corresponding pollution load to the wastewater treatment plant was reduced. Besides the tangible improvements, other gains were achieved, such as improved product quality, improved health and safety conditions, reduced maintenance requirements, and ensured compliance with national and EU regulations. To the best of the authors' knowledge, this study is the first ever activity in Turkey devoted to climate change adaptation in the private sector. This study may serve as a building block in Turkey for the integration of climate change adaptation and mitigation approach in the industry, since water efficiency (adaptation) and carbon reduction (mitigation) are achieved simultaneously. PMID:25630123

  4. Improved Adaptive-Reinforcement Learning Control for morphing unmanned air vehicles.

    Valasek, John; Doebbler, James; Tandale, Monish D; Meade, Andrew J

    2008-08-01

    This paper presents an improved Adaptive-Reinforcement Learning Control methodology for the problem of unmanned air vehicle morphing control. The reinforcement learning morphing control function that learns the optimal shape change policy is integrated with an adaptive dynamic inversion control trajectory tracking function. An episodic unsupervised learning simulation using the Q-learning method is developed to replace an earlier and less accurate Actor-Critic algorithm. Sequential Function Approximation, a Galerkin-based scattered data approximation scheme, replaces a K-Nearest Neighbors (KNN) method and is used to generalize the learning from previously experienced quantized states and actions to the continuous state-action space, all of which may not have been experienced before. The improved method showed smaller errors and improved learning of the optimal shape compared to the KNN. PMID:18632393

  5. Improving exposure assessment in environmental epidemiology: Application of spatio-temporal visualization tools

    Meliker, Jaymie R.; Slotnick, Melissa J.; Avruskin, Gillian A.; Kaufmann, Andrew; Jacquez, Geoffrey M.; Nriagu, Jerome O.

    2005-05-01

    A thorough assessment of human exposure to environmental agents should incorporate mobility patterns and temporal changes in human behaviors and concentrations of contaminants; yet the temporal dimension is often under-emphasized in exposure assessment endeavors, due in part to insufficient tools for visualizing and examining temporal datasets. Spatio-temporal visualization tools are valuable for integrating a temporal component, thus allowing for examination of continuous exposure histories in environmental epidemiologic investigations. An application of these tools to a bladder cancer case-control study in Michigan illustrates continuous exposure life-lines and maps that display smooth, continuous changes over time. Preliminary results suggest increased risk of bladder cancer from combined exposure to arsenic in drinking water (>25 μg/day) and heavy smoking (>30 cigarettes/day) in the 1970s and 1980s, and a possible cancer cluster around automotive, paint, and organic chemical industries in the early 1970s. These tools have broad application for examining spatially- and temporally-specific relationships between exposures to environmental risk factors and disease.

  6. An improved adaptive sampling and experiment design method for aerodynamic optimization

    Huang Jiangtao

    2015-10-01

    Full Text Available Experiment design method is a key to construct a highly reliable surrogate model for numerical optimization in large-scale project. Within the method, the experimental design criterion directly affects the accuracy of the surrogate model and the optimization efficient. According to the shortcomings of the traditional experimental design, an improved adaptive sampling method is proposed in this paper. The surrogate model is firstly constructed by basic sparse samples. Then the supplementary sampling position is detected according to the specified criteria, which introduces the energy function and curvature sampling criteria based on radial basis function (RBF network. Sampling detection criteria considers both the uniformity of sample distribution and the description of hypersurface curvature so as to significantly improve the prediction accuracy of the surrogate model with much less samples. For the surrogate model constructed with sparse samples, the sample uniformity is an important factor to the interpolation accuracy in the initial stage of adaptive sampling and surrogate model training. Along with the improvement of uniformity, the curvature description of objective function surface gradually becomes more important. In consideration of these issues, crowdness enhance function and root mean square error (RMSE feedback function are introduced in C criterion expression. Thus, a new sampling method called RMSE and crowdness enhance (RCE adaptive sampling is established. The validity of RCE adaptive sampling method is studied through typical test function firstly and then the airfoil/wing aerodynamic optimization design problem, which has high-dimensional design space. The results show that RCE adaptive sampling method not only reduces the requirement for the number of samples, but also effectively improves the prediction accuracy of the surrogate model, which has a broad prospects for applications.

  7. Moving forward with prisms: Sensory-motor adaptation improves gait initiation in Parkinson’s disease.

    Janet Helen Bultitude

    2012-09-01

    Full Text Available It is postulated that the decreased walking speed; small, shuffling steps; and ‘freezing’ shown by patients with Parkinson’s disease could stem from an inability to tilt the body forward enough to provide sufficient forward propulsion. In two repeated-measures studies we examined whether adaptation to upward-shifting prisms, resulting in a downward after-effect, could improve gait initiation in healthy participants and patients with Parkinson’s disease. Faster forward stepping followed a brief (5 min exposure period for patients, and a longer (20 min exposure period for age-matched controls. Backward stepping was unchanged, and adaptation to downward-shifting prisms with control participants showed no effect on forward or backward stepping. These results suggest that adaptation of arm proprioception in the vertical plane may generalise to anterior-posterior postural control, presenting new possibilities for the treatment of gait disturbance in basal ganglia disorders.

  8. A self-adaptive step Cuckoo search algorithm based on dimension by dimension improvement

    Lu REN

    2015-10-01

    Full Text Available The choice of step length plays an important role in convergence speed and precision of Cuckoo search algorithm. In the paper, a self-adaptive step Cuckoo search algorithm based on dimensional improvement is provided. First, since the step in the original self-adaptive step Cuckoo search algorithm is not updated when the current position of the nest is in the optimal position, simple modification of the step is made for the update. Second, evaluation strategy based on dimension by dimension update is introduced to the modified self-adaptive step Cuckoo search algorithm. The experimental results show that the algorithm can balance the contradiction between the global convergence ability and the precision of optimization. Moreover, the proposed algorithm has better convergence speed.

  9. An improved adaptive Sage filter with applications in GEO orbit determination and GPS kinematic positioning

    XU TianHe; JIANG Nan; SUN ZhangZhen

    2012-01-01

    The shortcomings of an adaptive Sage filter are analyzed in this paper.An improved adaptive Sage filter is developed by using a weighted average quadratic form of the historical residuals of observations and predicted states to evaluate the covariance matrices of observations and dynamic model errors at the present epoch.The weight function is constructed based on the variances of observational residuals or predicted state residuals and the space distance between the previous and the present epoch.In order to balance the contributions of the measurements and the dynamic model information,an adaptive factor is applied by using a two-segment function and predicted state discrepancy statistics.Two applications,orbit determination of a maneuvered GEO satellite and GPS kinematic positioning,are conducted to verify the performance of the proposed method.

  10. Locomotor Adaptation Improves Balance Control, Multitasking Ability and Reduces the Metabolic Cost of Postural Instability

    Bloomberg, J. J.; Peters, B. T.; Mulavara, A. P.; Brady, R. A.; Batson, C. D.; Miller, C. A.; Ploutz-Snyder, R. J.; Guined, J. R.; Buxton, R. E.; Cohen, H. S.

    2011-01-01

    During exploration-class missions, sensorimotor disturbances may lead to disruption in the ability to ambulate and perform functional tasks during the initial introduction to a novel gravitational environment following a landing on a planetary surface. The overall goal of our current project is to develop a sensorimotor adaptability training program to facilitate rapid adaptation to these environments. We have developed a unique training system comprised of a treadmill placed on a motion-base facing a virtual visual scene. It provides an unstable walking surface combined with incongruent visual flow designed to enhance sensorimotor adaptability. Greater metabolic cost incurred during balance instability means more physical work is required during adaptation to new environments possibly affecting crewmembers? ability to perform mission critical tasks during early surface operations on planetary expeditions. The goal of this study was to characterize adaptation to a discordant sensory challenge across a number of performance modalities including locomotor stability, multi-tasking ability and metabolic cost. METHODS: Subjects (n=15) walked (4.0 km/h) on a treadmill for an 8 -minute baseline walking period followed by 20-minutes of walking (4.0 km/h) with support surface motion (0.3 Hz, sinusoidal lateral motion, peak amplitude 25.4 cm) provided by the treadmill/motion-base system. Stride frequency and auditory reaction time were collected as measures of locomotor stability and multi-tasking ability, respectively. Metabolic data (VO2) were collected via a portable metabolic gas analysis system. RESULTS: At the onset of lateral support surface motion, subj ects walking on our treadmill showed an increase in stride frequency and auditory reaction time indicating initial balance and multi-tasking disturbances. During the 20-minute adaptation period, balance control and multi-tasking performance improved. Similarly, throughout the 20-minute adaptation period, VO2 gradually

  11. Adaptive slab laser beam quality improvement using a weighted least-squares reconstruction algorithm.

    Chen, Shanqiu; Dong, LiZhi; Chen, XiaoJun; Tan, Yi; Liu, Wenjin; Wang, Shuai; Yang, Ping; Xu, Bing; Ye, YuTang

    2016-04-10

    Adaptive optics is an important technology for improving beam quality in solid-state slab lasers. However, there are uncorrectable aberrations in partial areas of the beam. In the criterion of the conventional least-squares reconstruction method, it makes the zones with small aberrations nonsensitive and hinders this zone from being further corrected. In this paper, a weighted least-squares reconstruction method is proposed to improve the relative sensitivity of zones with small aberrations and to further improve beam quality. Relatively small weights are applied to the zones with large residual aberrations. Comparisons of results show that peak intensity in the far field improved from 1242 analog digital units (ADU) to 2248 ADU, and beam quality β improved from 2.5 to 2.0. This indicates the weighted least-squares method has better performance than the least-squares reconstruction method when there are large zonal uncorrectable aberrations in the slab laser system. PMID:27139877

  12. An Improved NMS-Based Adaptive Edge Detection Method and Its FPGA Implementation

    Enzeng Dong

    2016-01-01

    Full Text Available For improving the processing speed and accuracy of edge detection, an adaptive edge detection method based on improved NMS (nonmaximum suppression was proposed in this paper. In the method, the gradient image was computed by four directional Sobel operators. Then, the gradient image was processed by using NMS method. By defining a power map function, the elements values of gradient image histogram were mapped into a wider value range. By calculating the maximal between-class variance according to the mapped histogram, the corresponding threshold was obtained as adaptive threshold value in edge detection. Finally, to be convenient for engineering application, the proposed method was realized in FPGA (Field Programmable Gate Array. The experiment results demonstrated that the proposed method was effective in edge detection and suitable for real-time application.

  13. Deeper Into the Folksonomy Graph: FolkRank Adaptations and Extensions for Improved Tag Recommendations

    Landia, Nikolas; Doerfel, Stephan; Jäschke, Robert; Anand, Sarabjot Singh; Hotho, Andreas; Griffiths, Nathan

    2013-01-01

    The information contained in social tagging systems is often modelled as a graph of connections between users, items and tags. Recommendation algorithms such as FolkRank, have the potential to leverage complex relationships in the data, corresponding to multiple hops in the graph. We present an in-depth analysis and evaluation of graph models for social tagging data and propose novel adaptations and extensions of FolkRank to improve tag recommendations. We highlight implicit assumptions made ...

  14. Age-related improvements in auditory temporal resolution in reading-impaired children.

    Hautus, Michael J; Setchell, Gregory J; Waldie, Karen E; Kirk, Ian J

    2003-02-01

    Individuals with developmental dyslexia show impairments in processing that require precise timing of sensory events. Here, we show that in a test of auditory temporal acuity (a gap-detection task) children ages 6-9 years with dyslexia exhibited a significant deficit relative to age-matched controls. In contrast, this deficit was not observed in groups of older reading-impaired individuals (ages 10-11 years; 12-13 years) or in adults (ages 23-25 years). It appears, therefore, that early temporal resolution deficits in those with reading impairments may significantly ameliorate over time. However, the occurrence of an early deficit in temporal acuity may be antecedent to other language-related perceptual problems (particularly those related to phonological processing) that persist after the primary deficit has resolved. This result suggests that if remedial interventions targeted at temporal resolution deficits are to be effective, the early detection of the deficit and early application of the remedial programme is especially critical. PMID:12625375

  15. Improved Cerebral Function in Mesial Temporal Lobe Epilepsy after Subtemporal Amygdalohippocampectomy

    Takaya, Shigetoshi; Mikuni, Nobuhiro; Mitsueda, Takahiro; Satow, Takeshi; Taki, Junya; Kinoshita, Masako; Miyamoto, Susumu; Hashimoto, Nobuo; Ikeda, Akio; Fukuyama, Hidenao

    2009-01-01

    The functional changes that occur throughout the human brain after the selective removal of an epileptogenic lesion remain unclear. Subtemporal selective amygdalohippocampectomy (SAH) has been advocated as a minimally invasive surgical procedure for patients with medically intractable mesial temporal lobe epilepsy (MTLE). We evaluated the effects…

  16. Gait adaptability training improves obstacle avoidance and dynamic stability in patients with cerebellar degeneration.

    Fonteyn, Ella M R; Heeren, Anita; Engels, Jasper-Jan C; Boer, Jasper J Den; van de Warrenburg, Bart P C; Weerdesteyn, Vivian

    2014-01-01

    Balance and gait problems in patients with cerebellar degeneration lead to reduced mobility, loss of independence, and frequent falls. It is currently unclear, however, whether balance and gait capacities can be improved by training in this group of patients. Therefore, the aim of this study was to examine the effects of gait adaptability training on obstacle avoidance and dynamic stability during adaptive gait. Ten patients with degenerative cerebellar ataxia received 10 protocolized gait adaptability training sessions of 1 h each during 5 weeks. Training was performed on a treadmill with visual stepping targets and obstacles projected on the belt's surface. As the primary outcome, we used an obstacle avoidance task while walking on a treadmill. We determined avoidance success rates, as well as dynamic stability during the avoidance manoeuvre. Clinical ratings included the scale for the assessment of ataxia (SARA), 10 m walking test, timed up-and-go test, berg balance scale, and the obstacle subtask of the emory functional ambulation profile (EFAP). Following the intervention, success rates on the obstacle avoidance task had significantly improved compared to pre-intervention. For successful avoidance, participants allowed themselves smaller stability margins in the sagittal plane in the (shortened) pre-crossing step. However, in the subsequent steps they returned to baseline stability values more effectively than before training. SARA scores and the EFAP obstacle subtask improved significantly as well. This pilot study provides preliminary evidence of a beneficial effect of gait adaptability training on obstacle avoidance capacity and dynamic stability in patients with cerebellar degeneration. PMID:24786476

  17. An Improved Variable Structure Adaptive Filter Design and Analysis for Acoustic Echo Cancellation

    A. Kar

    2015-04-01

    Full Text Available In this research an advance variable structure adaptive Multiple Sub-Filters (MSF based algorithm for single channel Acoustic Echo Cancellation (AEC is proposed and analyzed. This work suggests a new and improved direction to find the optimum tap-length of adaptive filter employed for AEC. The structure adaptation, supported by a tap-length based weight update approach helps the designed echo canceller to maintain a trade-off between the Mean Square Error (MSE and time taken to attain the steady state MSE. The work done in this paper focuses on replacing the fixed length sub-filters in existing MSF based AEC algorithms which brings refinements in terms of convergence, steady state error and tracking over the single long filter, different error and common error algorithms. A dynamic structure selective coefficient update approach to reduce the structural and computational cost of adaptive design is discussed in context with the proposed algorithm. Simulated results reveal a comparative performance analysis over proposed variable structure multiple sub-filters designs and existing fixed tap-length sub-filters based acoustic echo cancellers.

  18. Research on Improved Adaptive Control for Static Synchronous Compensator in Power System

    Chao Zhang

    2015-01-01

    Full Text Available This paper deals with the problems of “explosion of term,” uncertain parameter in static synchronous compensator (STATCOM system with nonlinear time-delay. An improved adaptive controller is proposed to enhance the transient stability of system states and reduce computational complexity of STATCOM control system. In contrast to backstepping control scheme in high order systems, the problem of “explosion of term” is avoided by designing dynamic surface controller. The low pass filter is included to allow a design where the model is not differentiated and thus has prevented the mathematical complexities effectively. In addition, unlike the traditional adaptive control schemes, the certainty equivalence principle is not required for estimating the uncertain parameter by system immersion and manifold invariant (I&I adaptive control. A smooth function is added to ensure that the estimation error converges to zero in finite time. The effectiveness of the proposed controller is verified by the simulations. Compared with adaptive backstepping and proportion integration differentiation (PID, the oscillation amplitudes of transient response are reduced by nearly half, and the time of reaching steady state is shortened by at least 11%.

  19. Improving Early Adaptation Following Long Duration Spaceflight by Enhancing Vestibular Information

    Mulavara, Ajitkumar; Kofman, Igor; DeDios, Yiri E.; Galvan, Raquel; Miller, Chris; Peters, Brian; Cohen, Helen; Jeevarajan, Jerome; Reschke, Millard; Wood, Scott; Bloomberg, Jacob

    2014-01-01

    Crewmember adapted to the microgravity state may need to egress the vehicle within a few minutes for safety and operational reasons after g-transitions. The transition from one sensorimotor state to another consists of two main mechanisms: strategic and plastic-adaptive and have been demonstrated in astronauts returning after long duration space flight. Strategic modifications represent "early adaptation" -immediate and transitory changes in control that are employed to deal with short-term changes in the environment. If these modifications are prolonged then plastic-adaptive changes are evoked that modify central nervous system function, automating new behavioral responses. More importantly, this longer term adaptive recovery mechanism was significantly associated with their strategic ability to recover on the first day after return to Earth G. We are developing a method based on stochastic resonance (SR) to enhance information transfer by improving the brain's ability to detect vestibular signals especially when combined with balance training exercises for rapid improvement in functional skill, for standing and mobility. The countermeasure to improve post-flight balance and locomotor disturbances is a stimulus delivery system that is wearable/portable providing low imperceptible levels of white noise based binaural bipolar electrical stimulation of the vestibular system (stochastic vestibular stimulation, SVS). The techniques for improving signal detection using SVS may thus provide additional information to improve such strategic abilities and thus help in significantly reducing the number of days required to recover functional performance to preflight levels after long duration space flight. We have conducted a series of studies to document the efficacy of SVS stimulation on balance/locomotion tasks on unstable surfaces and motion tracking tasks during intra-vestibular system conflicts. In an initial study, we showed that SVS improved overall balance

  20. Improvement of the temporal resolution of cardiac CT reconstruction algorithms using an optimized filtering step

    In this paper we study a property of the filtering step of multi-cycle reconstruction algorithm used in the field of cardiac CT. We show that the common filtering step procedure is not optimal in the case of divergent geometry and decrease slightly the temporal resolution. We propose to use the filtering procedure related to the work of Noo at al ( F.Noo, M. Defrise, R. Clakdoyle, and H. Kudo. Image reconstruction from fan-beam projections on less than a short-scan. Phys. Med.Biol., 47:2525-2546, July 2002)and show that this alternative allows to reach the optimal temporal resolution with the same computational effort. (N.C.)

  1. Improvement of the temporal resolution of cardiac CT reconstruction algorithms using an optimized filtering step

    Roux, S. [Universite Joseph Fourier, TIMC-IMAG, In3S, Faculte de Medecine, 38 - Grenoble (France)]|[CEA Grenoble, Lab. d' Electronique et de Technologie de l' Informatique (LETI), 38 (France); Desbat, L. [Universite Joseph Fourier, UMR CNRS 5525, 38 - Grenoble (France); Koenig, A.; Grangeat, P. [CEA Grenoble, Lab. d' Electronique et de Technologie de l' Informatique (LETI), 38 (France)

    2005-07-01

    In this paper we study a property of the filtering step of multi-cycle reconstruction algorithm used in the field of cardiac CT. We show that the common filtering step procedure is not optimal in the case of divergent geometry and decrease slightly the temporal resolution. We propose to use the filtering procedure related to the work of Noo at al ( F.Noo, M. Defrise, R. Clakdoyle, and H. Kudo. Image reconstruction from fan-beam projections on less than a short-scan. Phys. Med.Biol., 47:2525-2546, July 2002)and show that this alternative allows to reach the optimal temporal resolution with the same computational effort. (N.C.)

  2. A technique for improved stability of adaptive feedforward controllers without detailed uncertainty measurements

    Model errors in adaptive controllers for the reduction of broadband noise and vibrations may lead to unstable systems or increased error signals. Previous research on active structures with small damping has shown that the addition of a low-authority controller which increases damping in the system may lead to improved performance of an adaptive, high-authority controller. Other researchers have suggested the use of frequency dependent regularization based on measured uncertainties. In this paper an alternative method is presented that avoids the disadvantages of these methods, namely the additional complex hardware and the need to obtain detailed information on the uncertainties. An analysis is made of an adaptive feedforward controller in which a difference exists between the secondary path and the model as used in the controller. The real parts of the eigenvalues that determine the stability of the system are expressed in terms of the amount of uncertainty and the singular values of the secondary path. Modifications of the feedforward control scheme are suggested that aim to improve performance without requiring detailed uncertainty measurements. (paper)

  3. SU-E-I-38: Improved Metal Artifact Correction Using Adaptive Dual Energy Calibration

    Purpose: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Methods: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Results: Highly attenuating copper rods cause severe streaking artifacts on standard CT images. EDEC improves the image quality, but cannot eliminate the streaking artifacts. Compared to EDEC, the proposed ADEC method further reduces the streaking resulting from metallic inserts and beam-hardening effects and obtains material decomposition images with significantly improved accuracy. Conclusion: We propose an adaptive dual energy calibration method to correct for metal artifacts. ADEC is evaluated with the Shepp-Logan phantom, and shows superior metal artifact correction performance. In the future, we will further evaluate the performance of the proposed method with phantom and patient data

  4. SU-E-I-38: Improved Metal Artifact Correction Using Adaptive Dual Energy Calibration

    Dong, X; Elder, E; Roper, J; Dhabaan, A [Winship Cancer Institute of Emory University (United States)

    2015-06-15

    Purpose: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Methods: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Results: Highly attenuating copper rods cause severe streaking artifacts on standard CT images. EDEC improves the image quality, but cannot eliminate the streaking artifacts. Compared to EDEC, the proposed ADEC method further reduces the streaking resulting from metallic inserts and beam-hardening effects and obtains material decomposition images with significantly improved accuracy. Conclusion: We propose an adaptive dual energy calibration method to correct for metal artifacts. ADEC is evaluated with the Shepp-Logan phantom, and shows superior metal artifact correction performance. In the future, we will further evaluate the performance of the proposed method with phantom and patient data.

  5. Incorporating temporal variability to improve geostatistical analysis of satellite-observed CO2 in China

    ZENG ZhaoCheng; LEI LiPing; GUO LiJie; ZHANG Li; ZHANG Bing

    2013-01-01

    Observations of atmospheric carbon dioxide (CO2) from satellites offer new data sources to understand global carbon cycling.The correlation structure of satellite-observed CO2 can be analyzed and modeled by geostatistical methods,and CO2 values at unsampled locations can be predicted with a correlation model.Conventional geostatistical analysis only investigates the spatial correlation of CO2,and does not consider temporal variation in the satellite-observed CO2 data.In this paper,a spatiotemporal geostatistical method that incorporates temporal variability is implemented and assessed for analyzing the spatiotemporal correlation structure and prediction of monthly CO2 in China.The spatiotemporal correlation is estimated and modeled by a product-sum variogram model with a global nugget component.The variogram result indicates a significant degree of temporal correlation within satellite-observed CO2 data sets in China.Prediction of monthly CO2 using the spatiotemporal variogram model and spacetime kriging procedure is implemented.The prediction is compared with a spatial-only geostatistical prediction approach using a cross-validation technique.The spatiotemporal approach gives better results,with higher correlation coefficient (r2),and less mean absolute prediction error and root mean square error.Moreover,the monthly mapping result generated from the spatiotemporal approach has less prediction uncertainty and more detailed spatial variation of CO2 than those from the spatial-only approach.

  6. Adaptive Harmonic Detection Control of Grid Interfaced Solar Photovoltaic Energy System with Power Quality Improvement

    Singh, B.; Goel, S.

    2015-03-01

    This paper presents a grid interfaced solar photovoltaic (SPV) energy system with a novel adaptive harmonic detection control for power quality improvement at ac mains under balanced as well as unbalanced and distorted supply conditions. The SPV energy system is capable of compensation of linear and nonlinear loads with the objectives of load balancing, harmonics elimination, power factor correction and terminal voltage regulation. The proposed control increases the utilization of PV infrastructure and brings down its effective cost due to its other benefits. The adaptive harmonic detection control algorithm is used to detect the fundamental active power component of load currents which are subsequently used for reference source currents estimation. An instantaneous symmetrical component theory is used to obtain instantaneous positive sequence point of common coupling (PCC) voltages which are used to derive inphase and quadrature phase voltage templates. The proposed grid interfaced PV energy system is modelled and simulated in MATLAB Simulink and its performance is verified under various operating conditions.

  7. Application and improvement of an adaptive ensemble Kalman filter for soil moisture data assimilation

    2010-01-01

    Accurate assignment of model and observation errors is crucial for the successful application of land surface data assimilation algorithms. Poorly-specified model and observation errors can significantly degrade assimilation results. In 2008, Reichle et al. developed an operational procedure to adaptively tune model and observation errors. In this paper, we modified and applied Reichle’s procedure in the Noah land surface model to assimilate observed surface soil moisture data. Numerical simulations showed that: (1) the best estimate of model and observation errors appears when the empirical factor β equals 1.02; (2) the Reichle procedure can be deployed to adaptively tune errors if their true values change slowly; and (3) convergence of the Reichle procedure was improved using better initial errors achieved by iterative computations.

  8. Genomic Measures to Predict Adaptation to Novel Sensorimotor Environments and Improve Personalization of Countermeasure Design

    Kreutzberg, G. A.; Zanello, S.; Seidler, R. D.; Peters, B.; De Dios, Y. E.; Gadd, N. E.; Bloomberg, J. J.; Mulavara, A. P.

    2016-01-01

    Introduction. Astronauts experience sensorimotor disturbances during their initial exposure to microgravity and during the re-adaptation phase following a return to an Earth-gravitational environment. These alterations may affect crewmembers' ability to perform mission-critical functional tasks. Interestingly, astronauts have shown significant inter-subject variation in adaptive capability during gravitational transitions. The ability to predict the manner and degree to which individual astronauts would be affected would improve the efficacy of personalized countermeasure training programs designed to enhance sensorimotor adaptability. The success of such an approach depends on the development of predictive measures of sensorimotor adaptation, which would ascertain each crewmember's adaptive capacity. The goal of this study is to determine whether specific genetic polymorphisms have significant influence on sensorimotor adaptability, which can help inform the design of personalized training countermeasures. Methods. Subjects (n=15) were tested on their ability to negotiate a complex obstacle course for ten test trials while wearing up-down vision-displacing goggles. This presented a visuomotor challenge while doing a full body task. The first test trial time and the recovery rate over the ten trials were used as adaptability performance metrics. Four single nucleotide polymorphisms (SNPs) were selected for their role in neural pathways underlying sensorimotor adaptation and were identified in subjects' DNA extracted from saliva samples: catechol-O-methyl transferase (COMT, rs4680), dopamine receptor D2 (DRD2, rs1076560), brain-derived neurotrophic factor genes (BDNF, rs6265), and the DraI polymorphism of the alpha-2 adrenergic receptor. The relationship between the SNPs and test performance was assessed by assigning subjects a rank score based on their adaptability performance metrics and comparing gene expression between the top half and bottom half performers

  9. Temporal and spatial binning of TCSPC data to improve signal-to-noise ratio and imaging speed

    Walsh, Alex J.; Beier, Hope T.

    2016-03-01

    Time-correlated single photon counting (TCSPC) is the most robust method for fluorescence lifetime imaging using laser scanning microscopes. However, TCSPC is inherently slow making it ineffective to capture rapid events due to the single photon product per laser pulse causing extensive acquisition time limitations and the requirement of low fluorescence emission efficiency to avoid bias of measurement towards short lifetimes. Furthermore, thousands of photons per pixel are required for traditional instrument response deconvolution and fluorescence lifetime exponential decay estimation. Instrument response deconvolution and fluorescence exponential decay estimation can be performed in several ways including iterative least squares minimization and Laguerre deconvolution. This paper compares the limitations and accuracy of these fluorescence decay analysis techniques to accurately estimate double exponential decays across many data characteristics including various lifetime values, lifetime component weights, signal-to-noise ratios, and number of photons detected. Furthermore, techniques to improve data fitting, including binning data temporally and spatially, are evaluated as methods to improve decay fits and reduce image acquisition time. Simulation results demonstrate that binning temporally to 36 or 42 time bins, improves accuracy of fits for low photon count data. Such a technique reduces the required number of photons for accurate component estimation if lifetime values are known, such as for commercial fluorescent dyes and FRET experiments, and improve imaging speed 10-fold.

  10. Improving LIGO calibration accuracy by tracking and compensating for slow temporal variations

    Tuyenbayev, D; Betzwieser, J; Cahillane, C; Goetz, E; Izumi, K; Kandhasamy, S; Kissel, J S; Mendell, G; Wade, M; Weinstein, A J; Savage, R L

    2016-01-01

    Calibration of the second-generation LIGO interferometric gravitational-wave detectors employs a method that uses injected periodic modulations to track and compensate for slow temporal variations in the differential length response of the instruments. These detectors utilize feedback control loops to maintain resonance conditions by suppressing differential arm length variations. We describe how the sensing and actuation functions of these servo loops are parameterized and how the slow variations in these parameters are quantified using the injected modulations. We report the results of applying this method to the LIGO detectors and show that it significantly reduces systematic errors in their calibrated outputs.

  11. Improved semisupervised adaptation for a small training dataset in the brain-computer interface.

    Meng, Jianjun; Sheng, Xinjun; Zhang, Dingguo; Zhu, Xiangyang

    2014-07-01

    One problem in the development of brain-computer interface (BCI) systems is to minimize the amount of subject training on the premise of accurate classification. Hence, the challenge is how to train the BCI system effectively especially in the scenario with small amount of training data. In this paper, we introduce improved semisupervised adaptation based on common spatial pattern (CSP) features. The feature extraction and classification are performed jointly and iteratively. In the iteration step, training data are expanded by part of the testing data with labels which are predicted by a linear discriminant analysis classifier and/or a Bayesian linear discriminant analysis classifier in the previous iteration. Then CSP features are reextracted from the expanded training data, and the classifiers are retrained. Both self-training and cotraining paradigms are proposed for the improved semisupervised adaptation. Throughout the investigation on different number of initial training trials, we find that when a small number of training trials are used, e.g., a training session contains no more than 30 trials, similar classification performance to that of large training data items (40-50 trials) can be achieved. Effectiveness of the algorithms is verified by two competition datasets. Compared with several existing algorithms, the proposed semisupervised algorithms show improvements in classification accuracy for most of the competition datasets especially in the case of small training data. PMID:24122610

  12. Environmental assessment, continual improvement and adaptive management within the AREVA sustainable development framework

    COGEMA Resources Inc. (which is part of the AREVA Group) is a Canadian company with its head office in Saskatoon, Saskatchewan. It owns and operates mining and milling facilities in northern Saskatchewan, which produce uranium concentrate. The McClean Lake Operation commenced production in 1999 and its environmental management system represents an integrated approach to environmental assessment, continual improvement and adaptive management based on operational results. In Canada, sustainable development is promoted through the application of the Canadian Environmental Assessment Act (CEAA). Environmental Assessment (EA) is a planning tool, which incorporates environmental considerations before irrevocable decisions are taken. The basic tenet of the Act is the determination of whether the potential environmental effects of a project are adverse, significant and likely, taking into consideration mitigation measures. Thus, project planning and design entails an iterative process that incorporates mitigation measures to minimize potentially significant adverse effects. As part of the EA process conservative approaches are taken to predict potential effects. Several important elements are generated through the EA process including: a set of environmental effects predictions, a compliance and environmental effects monitoring program, a follow-up program to address uncertainties in the prediction of environmental effects, and the identification of contingency measures that could be implemented should non-conservative assumptions be identified in the original assessment framework. The challenge is to integrate each of these elements into the environmental management framework of the operating facility and develop an iterative mechanism to evaluate operational performance relative to what was originally predicted. In Saskatchewan, a requirement of operational licenses is the periodic evaluation of the 'Status of the Environment' surrounding operational facilities. These

  13. Focal and temporal release of glutamate in the mushroom bodies improves olfactory memory in Apis mellifera.

    Locatelli, Fernando; Bundrock, Gesine; Müller, Uli

    2005-12-14

    In contrast to vertebrates, the role of the neurotransmitter glutamate in learning and memory in insects has hardly been investigated. The reason is that a pharmacological characterization of insect glutamate receptors is still missing; furthermore, it is difficult to locally restrict pharmacological interventions. In this study, we overcome these problems by using locally and temporally defined photo-uncaging of glutamate to study its role in olfactory learning and memory formation in the honeybee, Apis mellifera. Uncaging glutamate in the mushroom bodies immediately after a weak training protocol induced a higher memory rate 2 d after training, mimicking the effect of a strong training protocol. Glutamate release before training does not facilitate memory formation, suggesting that glutamate mediates processes triggered by training and required for memory formation. Uncaging glutamate in the antennal lobes shows no effect on memory formation. These results provide the first direct evidence for a temporally and locally restricted function of glutamate in memory formation in honeybees and insects. PMID:16354919

  14. Gait Adaptability Training Improves Both Postural Stability and Dual-Tasking Ability

    Brady, Rachel A.; Batson, Crystal D.; Peters, Brian T.; Ploutz-Snyder, Robert J.; Mulavara, Ajitkumar P.; Bloomberg, Jacob J.

    2010-01-01

    After spaceflight, the process of readapting to Earth's gravity commonly presents crewmembers with a variety of locomotor challenges. Our recent work has shown that the ability to adapt to a novel discordant sensorimotor environment can be increased through preflight training, so one focus of our laboratory has been the development of a gait training countermeasure to expedite the return of normal locomotor function after spaceflight. We used a training system comprising a treadmill mounted on a motion base facing a virtual visual scene that provided a variety of sensory challenges. As part of their participation in a larger retention study, 10 healthy adults completed 3 training sessions during which they walked on a treadmill at 1.1 m/s while receiving discordant support-surface and visual manipulations. After a single training session, subjects stride frequencies improved, and after 2 training sessions their auditory reaction times improved, where improvement was indicated by a return toward baseline values. Interestingly, improvements in reaction time came after stride frequency improvements plateaued. This finding suggests that postural stability was given a higher priority than a competing cognitive task. Further, it demonstrates that improvement in both postural stability and dual-tasking can be achieved with multiple training exposures. We conclude that, with training, individuals become more proficient at walking in discordant sensorimotor conditions and are able to devote more attention to competing tasks.

  15. An Improved Adaptive Multi-way Principal Component Analysis for Monitoring Streptomycin Fermentation Process

    何宁; 王树青; 谢磊

    2004-01-01

    Multi-way principal component analysis (MPCA) had been successfully applied to monitoring the batch and semi-batch process in most chemical industry. An improved MPCA approach, step-by-step adaptive MPCA (SAMPCA), using the process variable trajectories to monitoring the batch process is presented in this paper. It does not need to estimate or fill in the unknown part of the process variable trajectory deviation from the current time until the end. The approach is based on a MPCA method that processes the data in a sequential and adaptive manner. The adaptive rate is easily controlled through a forgetting factor that controls the weight of past data in a summation. This algorithm is used to evaluate the industrial streptomycin fermentation process data and is compared with the traditional MPCA. The results show that the method is more advantageous than MPCA, especially when monitoring multi-stage batch process where the latent vector structure can change at several points during the batch.

  16. Adaptive Agent Model with Hybrid Routing Selection Strategy for Improving the Road-Network Congestion Problem

    Bin Jiang; Chao Yang; Takao Terano

    2015-01-01

    This paper proposes an adaptive agent model with a hybrid routing selection strategy for studying the road⁃network congestion problem. We focus on improving those severely congested links. Firstly, a multi⁃agent system is built, where each agent stands for a vehicle, and it makes its routing selection by considering the shortest path and the minimum congested degree of the target link simultaneously. The agent⁃based model captures the nonlinear feedback between vehicle routing behaviors and road⁃network congestion status. Secondly, a hybrid routing selection strategy is provided, which guides the vehicle routes adapting to the real⁃time road⁃network congestion status. On this basis, we execute simulation experiments and compare the simulation results of network congestion distribution, by Floyd agent with shortest path strategy and our proposed adaptive agent with hybrid strategy. The simulation results show that our proposed model has reduced the congestion degree of those seriously congested links of road⁃network. Finally, we execute our model on a real road map. The results finds that those seriously congested roads have some common features such as located at the road junction or near the unique road connecting two areas. And, the results also show an effectiveness of our model on reduction of those seriously congested links in this actual road network. Such a bottom⁃up congestion control approach with a hybrid congestion optimization perspective will have its significance for actual traffic congestion control.

  17. Temporal contrast and spatial beam quality improvement techniques in a high intensity Ti:sapphire laser system

    This paper reviews the temporal contrast and spatial beam quality improvement techniques in a high intensity Ti:sapphire laser system that is based on chirped-pulse amplification (CPA). We describe an optical parametric chirped-pulse amplification (OPCPA) preamplifier that is seeded by a cleaned high-energy pulse. It demonstrates a background amplified spontaneous emission (ASE) level of 10-10 relative to the peak main femtosecond pulse on the picosecond timescale. We also report a cryogenically-cooled Ti:sapphire final amplifier which generates focused peak intensity in excess of 1020 W/cm2 at a 10 Hz repetition rate. (author)

  18. High baseline activity in inferior temporal cortex improves neural and behavioral discriminability during visual categorization

    Nazli eEmadi

    2014-11-01

    Full Text Available Spontaneous firing is a ubiquitous property of neural activity in the brain. Recent literature suggests that this baseline activity plays a key role in perception. However, it is not known how the baseline activity contributes to neural coding and behavior. Here, by recording from the single neurons in the inferior temporal cortex of monkeys performing a visual categorization task, we thoroughly explored the relationship between baseline activity, the evoked response, and behavior. Specifically we found that a low-frequency (< 8 Hz oscillation in the spike train, prior and phase-locked to the stimulus onset, was correlated with increased gamma power and neuronal baseline activity. This enhancement of the baseline activity was then followed by an increase in the neural selectivity and the response reliability and eventually a higher behavioral performance.

  19. Luminance and opponent-color contributions to visual detection and adaptation and to temporal and spatial integration.

    King-Smith, P E; Carden, D

    1976-07-01

    We show how the processes of visual detection and of temporal and spatial summation may be analyzed in terms of parallel luminance (achromatic) and opponent-color systems; a test flash is detected if it exceeds the threshold of either system. The spectral sensitivity of the luminance system may be determined by a flicker method, and has a single broad peak near 555 nm; the spectral sensitivity of the opponent-color system corresponds to the color recognition threshold, and has three peaks at about 440, 530, and 600 nm (on a white background). The temporal and spatial integration of the opponent-color system are generally greater than for the luminance system; further, a white background selectively depresses the sensitivity of the luminance system relative to the opponent-color system. Thus relatively large (1 degree) and long (200 msec) spectral test flashes on a white background are detected by the opponent-color system except near 570 nm; the contribution of the luminance system becomes more prominent if the size or duration of the test flash is reduced, or if the white background is extinguished. The present analysis is discussed in relation to Stiles' model of independent eta mechanisms. PMID:978286

  20. Improved temporal resolution in process-based modelling of agricultural soil ammonia emissions

    Beuning, J. D.; Pattey, E.; Edwards, G.; Van Heyst, B. J.

    An emerging environmental issue in Canada is how to quantify the contribution of agricultural soil emissions of ammonia (NH 3) to environmental pollution. Emission inventories are essential to predict these emissions and their subsequent atmospheric transportation, transformation, and deposition. Due to the high spatial and temporal variability associated with NH 3 emissions, emission inventories based on measurements become expensive and emission factors lose accuracy. Process-based models are capable of accounting for the complex soil interactions, but current models lack temporal refinement and few models consider NH 3 emissions. This paper presents the development of a one-dimensional (vertical), time-dependent model capable of predicting NH 3 emissions from a slurry applied to a bare soil. The model is based on chemical, physical and biological relationships that govern soil heat, moisture, and nitrogen movement. Processes considered include convection, diffusion, decomposition, nitrification, denitrification, and surface to atmosphere transport. The model is tested with experimental data from Agriculture and Agri-Food Canada which conducted NH 3 measurements following application of dairy cattle slurry to a bare field. An investigation into the sensitivity of emissions to pH and slurry infiltration rate is conducted and model predictions are best fit to measurements based on this investigation. Testing demonstrated the model's ability to predict the large NH 3 emissions immediately following application and subsequent emission trends associated with diurnal patterns that emission factors cannot capture. Results showed that model performance could benefit from a more in depth measurement program and empirical or process models of surface pH. Potential exists for the model to become a useful tool in predicting emissions on local, regional, or national scales.

  1. An adaptive threshold based image processing technique for improved glaucoma detection and classification.

    Issac, Ashish; Partha Sarathi, M; Dutta, Malay Kishore

    2015-11-01

    Glaucoma is an optic neuropathy which is one of the main causes of permanent blindness worldwide. This paper presents an automatic image processing based method for detection of glaucoma from the digital fundus images. In this proposed work, the discriminatory parameters of glaucoma infection, such as cup to disc ratio (CDR), neuro retinal rim (NRR) area and blood vessels in different regions of the optic disc has been used as features and fed as inputs to learning algorithms for glaucoma diagnosis. These features which have discriminatory changes with the occurrence of glaucoma are strategically used for training the classifiers to improve the accuracy of identification. The segmentation of optic disc and cup based on adaptive threshold of the pixel intensities lying in the optic nerve head region. Unlike existing methods the proposed algorithm is based on an adaptive threshold that uses local features from the fundus image for segmentation of optic cup and optic disc making it invariant to the quality of the image and noise content which may find wider acceptability. The experimental results indicate that such features are more significant in comparison to the statistical or textural features as considered in existing works. The proposed work achieves an accuracy of 94.11% with a sensitivity of 100%. A comparison of the proposed work with the existing methods indicates that the proposed approach has improved accuracy of classification glaucoma from a digital fundus which may be considered clinically significant. PMID:26321351

  2. Improved Adaptive Position Update for Geographic Routing in Mobile Ad Hoc Networks

    Mr.C.Nallusamy*1

    2014-06-01

    Full Text Available In geographic routing, the nodes ought to maintain up-to-date positions of their immediate neighbors. Periodic broadcasting of beacon packets that contain the geographic location coordinates of the nodes may be a new technique utilized by most geographic routing protocols to keep up neighbor positions. The traditional routing schemes demonstrate that periodic beaconing regardless of the node mobility and traffic patterns in the network are not attractive from both update cost and routing performance point of view. Since the Adaptive Position Update (APU strategy for geographic routing, which energetically regulates the frequency of position updates based on the mobility dynamics of the nodes and the forwarding patterns in the network. Generally in Mobile Ad Hoc Networks, if forwarding nodes have high mobility then it may have many chances to make local topology inaccurate in nature. Hence this new Improved Adaptive Position Update (IAPU technique for Geographic routing mainly enhances the APU with low mobility based forwarding node selection. This overcomes the link failure of the entire network in high mobility routing. Thus the experimental results exemplifies that the proposed approach drastically improves the performance of the existing APU.

  3. Improving the Thermal, Radial and Temporal Accuracy of the Analytical Ultracentrifuge through External References

    Ghirlando, Rodolfo; Balbo, Andrea; Piszczek, Grzegorz; Brown, Patrick H.; LEWIS, MARC S.; Brautigam, Chad A; Schuck, Peter; Zhao, Huaying

    2013-01-01

    Sedimentation velocity (SV) is a method based on first-principles that provides a precise hydrodynamic characterization of macromolecules in solution. Due to recent improvements in data analysis, the accuracy of experimental SV data emerges as a limiting factor in its interpretation. Our goal was to unravel the sources of experimental error and develop improved calibration procedures. We implemented the use of a Thermochron iButton® temperature logger to directly measure the temperature of a ...

  4. Improved spectral kurtosis with adaptive redundant multiwavelet packet and its applications for rotating machinery fault detection

    Rotating machinery fault detection is significant to avoid serious accidents and huge economic losses effectively. However, due to the vibration signal with the character of non-stationarity and nonlinearity, the detection and extraction of the fault feature turn into a challenging task. Therefore, a novel method called improved spectral kurtosis (ISK) with adaptive redundant multiwavelet packet (ARMP) is proposed for this task. Spectral kurtosis (SK) has been proved to be a powerful tool to detect and characterize the non-stationary signal. To improve the SK in filter limitation and enhance the resolution of spectral analysis as well as match fault feature optimally, the ARMP is introduced into the SK. Moreover, since kurtosis does not reflect the actual trend of periodic impulses, the SK is improved by incorporating an evaluation index called envelope spectrum entropy as supplement. The proposed method is applied to the rolling element bearing and gear fault detection to validate its reliability and effectiveness. Compared with the conventional frequency spectrum, envelope spectrum, original SK and some single wavelet methods, the results indicate that it could improve the accuracy of frequency-band selection and enhance the ability of rotating machinery fault detection. (paper)

  5. Improving Accuracy and Temporal Resolution of Learning Curve Estimation for within- and across-Session Analysis.

    Matthias Deliano

    Full Text Available Estimation of learning curves is ubiquitously based on proportions of correct responses within moving trial windows. Thereby, it is tacitly assumed that learning performance is constant within the moving windows, which, however, is often not the case. In the present study we demonstrate that violations of this assumption lead to systematic errors in the analysis of learning curves, and we explored the dependency of these errors on window size, different statistical models, and learning phase. To reduce these errors in the analysis of single-subject data as well as on the population level, we propose adequate statistical methods for the estimation of learning curves and the construction of confidence intervals, trial by trial. Applied to data from an avoidance learning experiment with rodents, these methods revealed performance changes occurring at multiple time scales within and across training sessions which were otherwise obscured in the conventional analysis. Our work shows that the proper assessment of the behavioral dynamics of learning at high temporal resolution can shed new light on specific learning processes, and, thus, allows to refine existing learning concepts. It further disambiguates the interpretation of neurophysiological signal changes recorded during training in relation to learning.

  6. Improving Accuracy and Temporal Resolution of Learning Curve Estimation for within- and across-Session Analysis.

    Deliano, Matthias; Tabelow, Karsten; König, Reinhard; Polzehl, Jörg

    2016-01-01

    Estimation of learning curves is ubiquitously based on proportions of correct responses within moving trial windows. Thereby, it is tacitly assumed that learning performance is constant within the moving windows, which, however, is often not the case. In the present study we demonstrate that violations of this assumption lead to systematic errors in the analysis of learning curves, and we explored the dependency of these errors on window size, different statistical models, and learning phase. To reduce these errors in the analysis of single-subject data as well as on the population level, we propose adequate statistical methods for the estimation of learning curves and the construction of confidence intervals, trial by trial. Applied to data from an avoidance learning experiment with rodents, these methods revealed performance changes occurring at multiple time scales within and across training sessions which were otherwise obscured in the conventional analysis. Our work shows that the proper assessment of the behavioral dynamics of learning at high temporal resolution can shed new light on specific learning processes, and, thus, allows to refine existing learning concepts. It further disambiguates the interpretation of neurophysiological signal changes recorded during training in relation to learning. PMID:27303809

  7. Development of Adaptive Feedback Control System of Both Spatial and Temporal Beam Shaping for UV-Laser Light Source for RF Gun

    Tomizawa, H; Dewa, H; Hanaki, H; Kobayashi, T; Mizuno, A; Suzuki, S; Taniuchi, T; Yanagida, K

    2004-01-01

    The ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from a photo-cathode rf gun. We have been developing highly qualified UV-laser pulse as a light source of the rf gun for an injector candidate of future light sources. The gun cavity is a single-cell pillbox, and the copper inner wall is used as a photo cathode. The electron beam was accelerated up to 4.1 MeV at the maximum electric field on the cathode surface of 175 MV/m. For emittance compensation, two solenoid coils were used. As the first test run, with a microlens array as a simple spatial shaper, we obtained a minimum emittance value of 2 π·mm·mrad with a beam energy of 3.1 MeV, holding its charge to 0.1 nC/bunch. In the next test run, we prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. We applied the both adaptive optics to automatically shape the bot...

  8. Study on Adaptive Slid Mode Controller for Improving Handling Stability of Motorized Electric Vehicles

    LiQiang Jin

    2014-01-01

    Full Text Available An adaptive slid mode controller was established for improving the handling stability of motorized electric vehicle (MEV. First and foremost, the structure and advantages of electric vehicle driven by in-wheel motors will be provided. Then, an ideal cornering model of vehicles will be brought and analyzed, after which a method to estimate side-slip angle was also proposed and three typical sensors were used in the theory. Besides, an idea for the recognition of road adhesion coefficient was derived based on MEV platform, which will be helpful for better control performances. Finally, the scheme of control method was given and some typical tests for observing handling properties were implemented based on Simulink and Carsim software. With the outcomes from the experiments, which vividly showed the merits of the controller, one can come to a conclusion that MEV that equips with the adaptive slid mode controller always enjoys better handling performances than the one without control. Furthermore, the controller researched is friendly to the real-time working conditions, which will hold practical values in the future.

  9. Pairwise adaptive thermostats for improved accuracy and stability in dissipative particle dynamics

    Leimkuhler, Benedict

    2016-01-01

    We examine the formulation and numerical treatment of dissipative particle dynamics (DPD) and momentum-conserving molecular dynamics. We show that it is possible to improve both the accuracy and the stability of DPD by employing a pairwise adaptive Langevin thermostat that precisely matches the dynamical characteristics of DPD simulations (e.g., autocorrelation functions) while automatically correcting thermodynamic averages using a negative feedback loop. In the low friction regime, it is possible to replace DPD by a simpler momentum-conserving variant of the Nos\\'{e}--Hoover--Langevin method based on thermostatting only pairwise interactions; we show that this method has an extra order of accuracy for an important class of observables (a superconvergence result), while also allowing larger timesteps than alternatives. All the methods mentioned in the article are easily implemented. Numerical experiments are performed in both equilibrium and nonequilibrium settings; using Lees--Edwards boundary conditions to...

  10. Improved optimal steering law for SGCMG and adaptive attitude control of flexible spacecraft

    Lu Wang; Yu Guo; Liping Wu; Qingwei Chen

    2015-01-01

    The issue of attitude maneuver of a flexible spacecraft is investigated with single gimbaled control moment gyroscopes (SGCMGs) as an actuator. To solve the inertia uncertainty of the system, an adaptive attitude control algorithm is designed by ap-plying a radial basis function (RBF) neural network. An improved steering law for SGCMGs is proposed to achieve the optimal out-put torque. It enables the SGCMGs not only to avoid singularity, but also to output more precise torque. In addition, global, uniform, ultimate bounded stability of the attitude control system is proved via the Lyapunov technique. Simulation results demonstrate the effectiveness of the new steering law and the algorithm of attitude maneuver of the flexible spacecraft.

  11. Adaptive spatial compounding for improving ultrasound images of the epidural space on human subjects

    Tran, Denis; Hor, King-Wei; Kamani, Allaudin; Lessoway, Vickie; Rohling, Robert N.

    2008-03-01

    Administering epidural anesthesia can be a difficult procedure, especially for inexperienced physicians. The use of ultrasound imaging can help by showing the location of the key surrounding structures: the ligamentum flavum and the lamina of the vertebrae. The anatomical depiction of the interface between ligamentum flavum and epidural space is currently limited by speckle and anisotropic reflection. Previous work on phantoms showed that adaptive spatial compounding with non-rigid registration can improve the depiction of these features. This paper describes the development of an updated compounding algorithm and results from a clinical study. Average-based compounding may obscure anisotropic reflectors that only appear at certain beam angles, so a new median-based compounding technique is developed. In order to reduce the computational cost of the registration process, a linear prediction algorithm is used to reduce the search space for registration. The algorithms are tested on 20 human subjects. Comparisons are made among the reference image plus combinations of different compounding methods, warping and linear prediction. The gradient of the bone surfaces, the Laplacian of the ligamentum flavum, and the SNR and CNR are used to quantitatively assess the visibility of the features in the processed images. The results show a significant improvement in quality when median-based compounding with warping is used to align the set of beam-steered images and combine them. The improvement of the features makes detection of the epidural space easier.

  12. Adapting the iSNOBAL model for improved visualization in a GIS environment

    Johansen, W. J.; Delparte, D.

    2014-12-01

    Snowmelt is a primary means of crucial water resources in much of the western United States. Researchers are developing models that estimate snowmelt to aid in water resource management. One such model is the image snowcover energy and mass balance (iSNOBAL) model. It uses input climate grids to simulate the development and melting of snowpack in mountainous regions. This study looks at applying this model to the Reynolds Creek Experimental Watershed in southwestern Idaho, utilizing novel approaches incorporating geographic information systems (GIS). To improve visualization of the iSNOBAL model, we have adapted it to run in a GIS environment. This type of environment is suited to both the input grid creation and the visualization of results. The data used for input grid creation can be stored locally or on a web-server. Kriging interpolation embedded within Python scripts are used to create air temperature, soil temperature, humidity, and precipitation grids, while built-in GIS and existing tools are used to create solar radiation and wind grids. Additional Python scripting is then used to perform model calculations. The final product is a user-friendly and accessible version of the iSNOBAL model, including the ability to easily visualize and interact with model results, all within a web- or desktop-based GIS environment. This environment allows for interactive manipulation of model parameters and visualization of the resulting input grids for the model calculations. Future work is moving towards adapting the model further for use in a 3D gaming engine for improved visualization and interaction.

  13. Spatio-temporal complexity of chimpanzee food: How cognitive adaptations can counteract the ephemeral nature of ripe fruit.

    Janmaat, Karline R L; Boesch, Christophe; Byrne, Richard; Chapman, Colin A; Goné Bi, Zoro B; Head, Josephine S; Robbins, Martha M; Wrangham, Richard W; Polansky, Leo

    2016-06-01

    Ecological complexity has been proposed to play a crucial role in primate brain-size evolution. However, detailed quantification of ecological complexity is still limited. Here we assess the spatio-temporal distribution of tropical fruits and young leaves, two primary chimpanzee (Pan troglodytes) foods, focusing on the predictability of their availability in individual trees. Using up to 20 years of information on monthly availability of young leaf, unripe and ripe fruit in plant species consumed by chimpanzees from tropical forests in East, Central, and West Africa, we estimated: (1) the forest-wide frequency of occurrence of each food type and (2) the predictability of finding ripe fruit-bearing trees, focusing on the timing, frequency, and amount of ripe fruit present. In all three forests, at least half of all encountered trees belonged to species that chimpanzees were known to feed on. However, the proportion of these trees bearing young leaves and fruit fluctuated widely between months. Ripe fruit was the most ephemeral food source, and trees that had more than half of their crown filled were at least nine times scarcer than other trees. In old growth forests only one large ripe fruit crop was on average encountered per 10 km. High levels of inter-individual variation in the number of months that fruit was present existed, and in some extreme cases individuals bore ripe fruit more than seven times as often as conspecifics. Some species showed substantially less variation in such ripe fruit production frequencies and fruit quantity than others. We hypothesize that chimpanzees employ a suite of cognitive mechanisms, including abilities to: (1) generalize or classify food trees; (2) remember the relative metrics of quantity and frequency of fruit production across years; and (3) flexibly plan return times to feeding trees to optimize high-energy food consumption in individual trees, and efficient travel between them. Am. J. Primatol. 78:626-645, 2016. © 2016

  14. The Effect of Adaptive Gain and Adaptive Momentum in Improving Training Time of Gradient Descent Back Propagation Algorithm on Classification Problems

    Norhamreeza Abdul Hamid

    2011-01-01

    Full Text Available The back propagation algorithm has been successfully applied to wide range of practical problems. Since this algorithm uses a gradient descent method, it has some limitations which are slow learning convergence velocity and easy convergence to local minima. The convergence behaviour of the back propagation algorithm depends on the choice of initial weights and biases, network topology, learning rate, momentum, activation function and value for the gain in the activation function. Previous researchers demonstrated that in ‘feed forward’ algorithm, the slope of the activation function is directly influenced by a parameter referred to as ‘gain’. This research proposed an algorithm for improving the performance of the current working back propagation algorithm which is Gradien Descent Method with Adaptive Gain by changing the momentum coefficient adaptively for each node. The influence of the adaptive momentum together with adaptive gain on the learning ability of a neural network is analysed. Multilayer feed forward neural networks have been assessed. Physical interpretation of the relationship between the momentum value, the learning rate and weight values is given. The efficiency of the proposed algorithm is compared with conventional Gradient Descent Method and current Gradient Descent Method with Adaptive Gain was verified by means of simulation on three benchmark problems. In learning the patterns, the simulations result demonstrate that the proposed algorithm converged faster on Wisconsin breast cancer with an improvement ratio of nearly 1.8, 6.6 on Mushroom problem and 36% better on  Soybean data sets. The results clearly show that the proposed algorithm significantly improves the learning speed of the current gradient descent back-propagatin algorithm.

  15. Adaptive Protocols to Improve TCP/IP Performance in an LMDS Network using a Broadband Channel Sounder

    Eshler, Todd Jacob

    2002-01-01

    Virginia Tech researchers have developed a broadband channel sounder that can measure channel quality while a wireless network is in operation. Channel measurements from the broadband sounder hold the promise of improving TCP/IP performance by trigging configuration changes in an adaptive data link layer protocol. We present an adaptive data link layer protocol that can use different levels of forward error correction (FEC) codes and link layer automatic retransmission request ...

  16. Shaping prestimulus neural activity with auditory rhythmic stimulation improves the temporal allocation of attention

    Pincham, Hannah L.; Cristoforetti, Giulia; Facoetti, Andrea; Szűcs, Dénes

    2016-01-01

    Human attention fluctuates across time, and even when stimuli have identical physical characteristics and the task demands are the same, relevant information is sometimes consciously perceived and at other times not. A typical example of this phenomenon is the attentional blink, where participants show a robust deficit in reporting the second of two targets (T2) in a rapid serial visual presentation (RSVP) stream. Previous electroencephalographical (EEG) studies showed that neural correlates of correct T2 report are not limited to the RSVP period, but extend before visual stimulation begins. In particular, reduced oscillatory neural activity in the alpha band (8-12 Hz) before the onset of the RSVP has been linked to lower T2 accuracy. We therefore examined whether auditory rhythmic stimuli presented at a rate of 10 Hz (within the alpha band) could increase oscillatory alpha-band activity and improve T2 performance in the attentional blink time window. Behaviourally, the auditory rhythmic stimulation worked to enhance T2 accuracy. This enhanced perception was associated with increases in the posterior T2-evoked N2 component of the event-related potentials and this effect was observed selectively at lag 3. Frontal and posterior oscillatory alpha-band activity was also enhanced during auditory stimulation in the pre-RSVP period and positively correlated with T2 accuracy. These findings suggest that ongoing fluctuations can be shaped by sensorial events to improve the allocation of attention in time. PMID:26986506

  17. White noise improves learning by modulating activity in dopaminergic midbrain regions and right superior temporal sulcus.

    Rausch, Vanessa H; Bauch, Eva M; Bunzeck, Nico

    2014-07-01

    In neural systems, information processing can be facilitated by adding an optimal level of white noise. Although this phenomenon, the so-called stochastic resonance, has traditionally been linked with perception, recent evidence indicates that white noise may also exert positive effects on cognitive functions, such as learning and memory. The underlying neural mechanisms, however, remain unclear. Here, on the basis of recent theories, we tested the hypothesis that auditory white noise, when presented during the encoding of scene images, enhances subsequent recognition memory performance and modulates activity within the dopaminergic midbrain (i.e., substantia nigra/ventral tegmental area, SN/VTA). Indeed, in a behavioral experiment, we can show in healthy humans that auditory white noise-but not control sounds, such as a sinus tone-slightly improves recognition memory. In an fMRI experiment, white noise selectively enhances stimulus-driven phasic activity in the SN/VTA and auditory cortex. Moreover, it induces stronger connectivity between SN/VTA and right STS, which, in addition, exhibited a positive correlation with subsequent memory improvement by white noise. Our results suggest that the beneficial effects of auditory white noise on learning depend on dopaminergic neuromodulation and enhanced connectivity between midbrain regions and the STS-a key player in attention modulation. Moreover, they indicate that white noise could be particularly useful to facilitate learning in conditions where changes of the mesolimbic system are causally related to memory deficits including healthy and pathological aging. PMID:24345178

  18. Shaping prestimulus neural activity with auditory rhythmic stimulation improves the temporal allocation of attention.

    Ronconi, Luca; Pincham, Hannah L; Cristoforetti, Giulia; Facoetti, Andrea; Szűcs, Dénes

    2016-05-01

    Human attention fluctuates across time, and even when stimuli have identical physical characteristics and the task demands are the same, relevant information is sometimes consciously perceived and at other times not. A typical example of this phenomenon is the attentional blink, where participants show a robust deficit in reporting the second of two targets (T2) in a rapid serial visual presentation (RSVP) stream. Previous electroencephalographical (EEG) studies showed that neural correlates of correct T2 report are not limited to the RSVP period, but extend before visual stimulation begins. In particular, reduced oscillatory neural activity in the alpha band (8-12 Hz) before the onset of the RSVP has been linked to lower T2 accuracy. We therefore examined whether auditory rhythmic stimuli presented at a rate of 10 Hz (within the alpha band) could increase oscillatory alpha-band activity and improve T2 performance in the attentional blink time window. Behaviourally, the auditory rhythmic stimulation worked to enhance T2 accuracy. This enhanced perception was associated with increases in the posterior T2-evoked N2 component of the event-related potentials and this effect was observed selectively at lag 3. Frontal and posterior oscillatory alpha-band activity was also enhanced during auditory stimulation in the pre-RSVP period and positively correlated with T2 accuracy. These findings suggest that ongoing fluctuations can be shaped by sensorial events to improve the allocation of attention in time. PMID:26986506

  19. Improving Temporal Coverage of an Energy-Efficient Data Extraction Algorithm for Environmental Monitoring Using Wireless Sensor Networks

    Supriyo Chatterjea

    2009-06-01

    Full Text Available Collecting raw data from a wireless sensor network for environmental monitoring applications can be a difficult task due to the high energy consumption involved. This is especially difficult when the application requires specialized sensors that have very high energy consumption, e.g. hydrological sensors for monitoring marine environments. This paper introduces a technique for reducing energy consumption by minimizing sensor sampling operations. In addition, we illustrate how a randomized algorithm can be used to improve temporal coverage such that the time between the occurrence of an event and its detection can be minimized. We evaluate our approach using real data collected from a sensor network deployment on the Great Barrier Reef.

  20. Using spatial, temporal and evidence-status data to improve ballistic imaging performance.

    Yang, Yan; Koffman, Avi; Hocherman, Gil; Wein, Lawrence M

    2014-01-01

    Firearms identification imaging systems help solve crimes by comparing newly acquired images of cartridge casings or bullets to a database of images obtained from past crime scenes. We formulate an optimization problem that bases its matching decisions not only on the similarity between pairs of images, but also on the time and spatial location of each new acquisition and each database entry. The objective is to maximize the detection probability subject to a constraint on the false positive rate. We use data on all cartridge casings matches detected in Israel during 2006-2008 to estimate most of the model parameters. We estimate matching accuracy from two different studies and predict that the optimal use of extraneous information would increase the detection probability from 0.931 to 0.987 and from 0.707 to 0.844, respectively. These improvements are achieved by favoring pairs of images that are closer together in space and time. PMID:24400829

  1. Adaptive Wavelet Threshold Denoising Method for Machinery Sound Based on Improved Fruit Fly Optimization Algorithm

    Jing Xu

    2016-07-01

    Full Text Available As the sound signal of a machine contains abundant information and is easy to measure, acoustic-based monitoring or diagnosis systems exhibit obvious superiority, especially in some extreme conditions. However, the sound directly collected from industrial field is always polluted. In order to eliminate noise components from machinery sound, a wavelet threshold denoising method optimized by an improved fruit fly optimization algorithm (WTD-IFOA is proposed in this paper. The sound is firstly decomposed by wavelet transform (WT to obtain coefficients of each level. As the wavelet threshold functions proposed by Donoho were discontinuous, many modified functions with continuous first and second order derivative were presented to realize adaptively denoising. However, the function-based denoising process is time-consuming and it is difficult to find optimal thresholds. To overcome these problems, fruit fly optimization algorithm (FOA was introduced to the process. Moreover, to avoid falling into local extremes, an improved fly distance range obeying normal distribution was proposed on the basis of original FOA. Then, sound signal of a motor was recorded in a soundproof laboratory, and Gauss white noise was added into the signal. The simulation results illustrated the effectiveness and superiority of the proposed approach by a comprehensive comparison among five typical methods. Finally, an industrial application on a shearer in coal mining working face was performed to demonstrate the practical effect.

  2. Improved Adaptive Routing for Multihop IEEE 802.15.6 Wireless Body Area Networks

    Shariar Imtiaz

    2013-11-01

    Full Text Available Wireless Body Area Network has the ability to collect and send data on body measurement to the server through PDA or other device. Nodes (sensors collect vital signs from the body or environmental factor and check them. In IEEE 802.15.6 routing is discussed as a part of the link layer where multihop is not fully considered. Improving network performance, reducing energy consumption, thus extending the network lifetime is the main challenge in BANs. Several studies mention that multihop for BANs helps for achieving network performance, reducing energy consumption and extending network lifetime. One work presents the Adaptive multihop tree-based Routing (AMR protocol that is extensively evaluated in a real testbed deployment. They use fuzzy logic to combine all metrics they use. Another limitation is that they have used Prim's algorithm which is not a realistic approach. So in this work we have improved their multihop tree-based Routing (AMR protocol using Kruskal's algorithm instead of Prim's algorithm. The time complexity of Kruskal's algorithm is way less than prims's algorithm. We have used network simulator 3 (NS3 to simulate and found that our algorithm is better than AMR if many of nodes.

  3. Spatial-temporal distribution of a Noctiluca scintillans population and its adaption to environmental conditions in northern South China Sea

    Yu Wang

    2012-11-01

    Full Text Available Based on the data of a Noctiluca scintillans population in northern South China Sea (107°00′–119°00′E, 16°00′–24°00′N obtained in project “Integrated Investigation and Assessment of China Seas”(coded as 908 project in 2006 and 2008, we described the spatial distribution in wide geographical areas and seasonal variations of a Noctiluca scintillans population using GIS spatial analysis modeling and mapping techniques. The adaption of Noctiluca scintillans to temperature, salinity and nutrients were also discussed. The results showed that abundance of Noctiluca scintillans varied from 0.001×104 cells/m3 to 64.5×104 cells/m3, with an average of (0.56±3.29×104 cells/m3(n = 1,424. Average abundance varied by season, spring > autumn > winter > summer, with highest and lowest abundances of (1.28±4.24×104 cells/m3 (n = 356 and (0.19±0.95×104 cells/m3 (n = 356, respectively. The spatial distribution of Noctiluca scintillans generally decreased from alongshore to offshore areas, in a pattern of discontinuous patches. Abundance assemblage zones laid along the shores of eastern Leizhou peninsula, where it was also the peak abundance region in winter. The zones of low annunal abundance were primarily in the northern South China Sea. Dapeng Bay in eastern Guangdong Province and Pearl River Estuary were not abundance assemblage zones during summer and winter months. We found the shore of southeastern Hainan Island became high abundance zones during summer months. Compared with data of national integrated investigations completed in 1958 and 1959, Noctiluca scintillans abundance increased abruptly with an evident change of abundance assemblage zones. The seasonal variation was obvious. Average Noctiluca scintillans abundance was 27 times higher than recorded in 1959. Noctiluca scintillans populations in South China Sea required a much higher temperature than it did in East, Yellow and Bohai Seas in China. Salinity fluctuations were

  4. TCP- Costco Reno: New Variant by Improving Bandwidth Estimation to adapt over MANETs

    Prakash B. Khelage

    2014-01-01

    Full Text Available The Transmission Control Protocol (TCP is traditional, dominant and has been de facto standard protocol, used as transport agent at transport layer of TCP/IP protocol suite. Basically it is designed to provide reliability and assure guaranty to end-to-end delivery of data over unreliable networks. In practice, most TCP deployments have been carefully designed in the context of wired networks. Ignoring the properties of wireless Ad Hoc Networks, therefore it can lead to TCP implementations with poor performance. The problem of TCP and all its existing variations within MANETs resides in its inability to distinguish between different data packet loss causes, whenever the data loss occur traditional TCP congestion control algorithm assumes loss is due to congestion episode and reduces sending parameters value unnecessary. Thus, TCP has not always the optimum behavior in front of packet losses which might cause network performance degradation and resources waste. In order to adapt TCP over mobile Ad hoc environment, improvements have been proposed based on RTT and BW estimation technique in the literature to help TCP to differentiate accurate causes between the different types of losses. But still does not handle all the problems accurately and effectively. In this paper, a proposed TCP-Costco Reno a New Variant, accurately estimates the available bandwidth over Mobile Ad Hoc networks and sets sending rate accordingly to maximize utilization of available resources and hence improves performance of TCP over mobile Ad hoc networks. The results of the simulation indicate an improvement in throughput over interference, link failure and signal loss validation scenarios. Further, it shows highest average of average throughput then those variants which are most successful over MANETs.

  5. Investigation of instabilities affecting detonations: Improving the resolution using block-structured adaptive mesh refinement

    Ravindran, Prashaanth

    The unstable nature of detonation waves is a result of the critical relationship between the hydrodynamic shock and the chemical reactions sustaining the shock. A perturbative analysis of the critical point is quite challenging due to the multiple spatio-temporal scales involved along with the non-linear nature of the shock-reaction mechanism. The author's research attempts to provide detailed resolution of the instabilities at the shock front. Another key aspect of the present research is to develop an understanding of the causality between the non-linear dynamics of the front and the eventual breakdown of the sub-structures. An accurate numerical simulation of detonation waves requires a very efficient solution of the Euler equations in conservation form with detailed, non-equilibrium chemistry. The difference in the flow and reaction length scales results in very stiff source terms, requiring the problem to be solved with adaptive mesh refinement. For this purpose, Berger-Colella's block-structured adaptive mesh refinement (AMR) strategy has been developed and applied to time-explicit finite volume methods. The block-structured technique uses a hierarchy of parent-child sub-grids, integrated recursively over time. One novel approach to partition the problem within a large supercomputer was the use of modified Peano-Hilbert space filling curves. The AMR framework was merged with CLAWPACK, a package providing finite volume numerical methods tailored for wave-propagation problems. The stiffness problem is bypassed by using a 1st order Godunov or a 2nd order Strang splitting technique, where the flow variables and source terms are integrated independently. A linearly explicit fourth-order Runge-Kutta integrator is used for the flow, and an ODE solver was used to overcome the numerical stiffness. Second-order spatial resolution is obtained by using a second-order Roe-HLL scheme with the inclusion of numerical viscosity to stabilize the solution near the discontinuity

  6. In situ adaptive response to climate and habitat quality variation: spatial and temporal variation in European badger (Meles meles) body weight.

    Byrne, Andrew W; Fogarty, Ursula; O'Keeffe, James; Newman, Chris

    2015-09-01

    Variation in climatic and habitat conditions can affect populations through a variety of mechanisms, and these relationships can act at different temporal and spatial scales. Using post-mortem badger body weight records from 15 878 individuals captured across the Republic of Ireland (7224 setts across ca. 15 000 km(2) ; 2009-2012), we employed a hierarchical multilevel mixed model to evaluate the effects of climate (rainfall and temperature) and habitat quality (landscape suitability), while controlling for local abundance (unique badgers caught/sett/year). Body weight was affected strongly by temperature across a number of temporal scales (preceding month or season), with badgers being heavier if preceding temperatures (particularly during winter/spring) were warmer than the long-term seasonal mean. There was less support for rainfall across different temporal scales, although badgers did exhibit heavier weights when greater rainfall occurred one or 2 months prior to capture. Badgers were also heavier in areas with higher landscape habitat quality, modulated by the number of individuals captured per sett, consistent with density-dependent effects reducing weights. Overall, the mean badger body weight of culled individuals rose during the study period (2009-2012), more so for males than for females. With predicted increases in temperature, and rainfall, augmented by ongoing agricultural land conversion in this region, we project heavier individual badger body weights in the future. Increased body weight has been associated with higher fecundity, recruitment and survival rates in badgers, due to improved food availability and energetic budgets. We thus predict that climate change could increase the badger population across the Republic of Ireland. Nevertheless, we emphasize that, locally, populations could still be vulnerable to extreme weather variability coupled with detrimental agricultural practice, including population management. PMID:25846328

  7. Aortic pressure wave reconstruction during exercise is improved by adaptive filtering: a pilot study.

    Stok, Wim J; Westerhof, Berend E; Guelen, Ilja; Karemaker, John M

    2011-08-01

    Reconstruction of central aortic pressure from a peripheral measurement by a generalized transfer function (genTF) works well at rest and mild exercise at lower heart rates, but becomes less accurate during heavy exercise. Particularly, systolic and pulse pressure estimations deteriorate, thereby underestimating central pressure. We tested individualization of the TF (indTF) by adapting its resonance frequency at the various levels of exercise. In seven males (age 44-57) with coronary artery disease, central and peripheral pressures were measured simultaneously. The optimal resonance frequency was predicted from regression formulas using variables derived from the individual's peripheral pressure pulse, including a pulse contour estimation of cardiac output (pcCO). In addition, reconstructed pressures were calibrated to central mean and diastolic pressure at each exercise level. Using a genTF and without calibration, the error in estimated aortic pulse pressure was -7.5 ± 6.4 mmHg, which was reduced to 0.2 ± 5.7 mmHg with the indTFs using pcCO for prediction. Calibration resulted in less scatter at the cost of a small bias (2.7 mmHg). In exercise, the indTFs predict systolic and pulse pressure better than the genTF. This pilot study shows that it is possible to individualize the peripheral to aortic pressure transfer function, thereby improving accuracy in central blood pressure assessment during exercise. PMID:21720842

  8. Improving conservation outcomes with a new paradigm for understanding species’ fundamental and realized adaptive capacity

    Beever, Erik; O’Leary, John; Mengelt, Claudia; West, Jordan M.; Julius, Susan; Green, Nancy; Magness, Dawn; Petes, Laura E.; Stein, Bruce A.; Nicotra, Adrienne B; Hellmann, Jessica J; Robertson, Amanda L; Staudinger, Michelle D.; Rosenberg, Andrew A.; Babij, Eleanora; Brennan, Jean; Schuurman, Gregor W; Hofmann, Gretchen E

    2016-01-01

    Worldwide, many species are responding to ongoing climate change with shifts in distribution, abundance, phenology, or behavior. Consequently, natural-resource managers face increasingly urgent conservation questions related to biodiversity loss, expansion of invasive species, and deteriorating ecosystem services. We argue that our ability to address these questions is hampered by the lack of explicit consideration of species’ adaptive capacity (AC). AC is the ability of a species or population to cope with climatic changes and is characterized by three fundamental components: phenotypic plasticity, dispersal ability, and genetic diversity. However, few studies simultaneously address all elements; often, AC is confused with sensitivity or omitted altogether from climate-change vulnerability assessments. Improved understanding, consistent definition, and comprehensive evaluations of AC are needed. Using classic ecological-niche theory as an analogy, we propose a new paradigm that considers fundamental and realized AC: the former reflects aspects inherent to species, whereas the latter denotes how extrinsic factors constrain AC to what is actually expressed or observed. Through this conceptualization, we identify ecological attributes contributing to AC, outline areas of research necessary to advance understanding of AC, and provide examples demonstrating how the inclusion of AC can better inform conservation and natural-resource management.

  9. An improved adaptive kriging-based importance technique for sampling multiple failure regions of low probability

    The estimation of system failure probabilities may be a difficult task when the values involved are very small, so that sampling-based Monte Carlo methods may become computationally impractical, especially if the computer codes used to model the system response require large computational efforts, both in terms of time and memory. This paper proposes a modification of an algorithm proposed in literature for the efficient estimation of small failure probabilities, which combines FORM to an adaptive kriging-based importance sampling strategy (AK-IS). The modification allows overcoming an important limitation of the original AK-IS in that it provides the algorithm with the flexibility to deal with multiple failure regions characterized by complex, non-linear limit states. The modified algorithm is shown to offer satisfactory results with reference to four case studies of literature, outperforming in general several other alternative methods of literature. - Highlights: • We tackle low failure probability estimation within reliability analysis context. • We improve a kriging-based importance sampling for estimating failure probabilities. • The new algorithm is capable of dealing with multiple-disconnected failure regions. • The performances are better than other methods of literature on 4 test case-studies

  10. Improved characterization of slow-moving landslides by means of adaptive NL-InSAR filtering

    Albiol, David; Iglesias, Rubén.; Sánchez, Francisco; Duro, Javier

    2014-10-01

    Advanced remote sensing techniques based on space-borne Synthetic Aperture Radar (SAR) have been developed during the last decade showing their applicability for the monitoring of surface displacements in landslide areas. This paper presents an advanced Persistent Scatterer Interferometry (PSI) processing based on the Stable Point Network (SPN) technique, developed by the company Altamira-Information, for the monitoring of an active slowmoving landslide in the mountainous environment of El Portalet, Central Spanish Pyrenees. For this purpose, two TerraSAR-X data sets acquired in ascending mode corresponding to the period from April to November 2011, and from August to November 2013, respectively, are employed. The objective of this work is twofold. On the one hand, the benefits of employing Nonlocal Interferomtric SAR (NL-InSAR) adaptive filtering techniques over vegetated scenarios to maximize the chances of detecting natural distributed scatterers, such as bare or rocky areas, and deterministic point-like scatterers, such as man-made structures or poles, is put forward. In this context, the final PSI displacement maps retrieved with the proposed filtering technique are compared in terms of pixels' density and quality with classical PSI, showing a significant improvement. On the other hand, since SAR systems are only sensitive to detect displacements in the line-of-sight (LOS) direction, the importance of projecting the PSI displacement results retrieved along the steepest gradient of the terrain slope is discussed. The improvements presented in this paper are particularly interesting in these type of applications since they clearly allow to better determine the extension and dynamics of complex landslide phenomena.

  11. Stability evaluation and improvement of adaptive optics systems by using the Lyapunov stability approach

    Wang, Liang; Chen, Tao; Liu, Xin-yue; Lin, Xu-dong; Yang, Xiao-xia; Li, Hong-zhuang

    2016-02-01

    In this research, investigations on the closed-loop control stability of adaptive optics systems are conducted by using the Lyapunov approach. As an direct metric of the control stability, the error propagator includes the effects of both the integral gain and the influence matrix and is effective for control-stability evaluation. An experimental 97-element AO system is developed for the control-stability investigation, and the Southwell sensor-actuator configuration rather than the Fried geometry is adopted so as to suppress the potential waffle mode. Because filtering out small singular values of the influence matrix can be used to improve the control stability, the effect of the influence matrix and the effect of the integral gain are considered as a whole by using the error propagator. Then, the control stability of the AO system is evaluated for varying the integral gains and the number of filtered-out singular values. Afterwards, an analysis of the evaluations of the error propagator is made, and a conclusion can be drawn that the control stability can be improved by filtering out more singular values of the influence matrix when the integral gain is high. In other words, the error propagator is useful for trading off the bandwidth error and the fitting error of AO systems in a control-stability approach. Finally, a performance measurement of the experimental AO system is conducted when 13 smaller singular values of the influence matrix are filtered out, and the results show that filtering out a small fraction of the singular values has a minor influence on the performance of this AO system.

  12. IL-15 prevents apoptosis, reverses innate and adaptive immune dysfunction, and improves survival in sepsis.

    Inoue, Shigeaki; Unsinger, Jacqueline; Davis, Christopher G; Muenzer, Jared T; Ferguson, Thomas A; Chang, Katherine; Osborne, Dale F; Clark, Andrew T; Coopersmith, Craig M; McDunn, Jonathan E; Hotchkiss, Richard S

    2010-02-01

    IL-15 is a pluripotent antiapoptotic cytokine that signals to cells of both the innate and adaptive immune system and is regarded as a highly promising immunomodulatory agent in cancer therapy. Sepsis is a lethal condition in which apoptosis-induced depletion of immune cells and subsequent immunosuppression are thought to contribute to morbidity and mortality. This study tested the ability of IL-15 to block apoptosis, prevent immunosuppression, and improve survival in sepsis. Mice were made septic using cecal ligation and puncture or Pseudomonas aeruginosa pneumonia. The experiments comprised a 2 x 2 full factorial design with surgical sepsis versus sham and IL-15 versus vehicle. In addition to survival studies, splenic cellularity, canonical markers of activation and proliferation, intracellular pro- and antiapoptotic Bcl-2 family protein expression, and markers of immune cell apoptosis were evaluated by flow cytometry. Cytokine production was examined both in plasma of treated mice and splenocytes that were stimulated ex vivo. IL-15 blocked sepsis-induced apoptosis of NK cells, dendritic cells, and CD8 T cells. IL-15 also decreased sepsis-induced gut epithelial apoptosis. IL-15 therapy increased the abundance of antiapoptotic Bcl-2 while decreasing proapoptotic Bim and PUMA. IL-15 increased both circulating IFN-gamma, as well as the percentage of NK cells that produced IFN-gamma. Finally, IL-15 increased survival in both cecal ligation and puncture and P. aeruginosa pneumonia. In conclusion, IL-15 prevents two immunopathologic hallmarks of sepsis, namely, apoptosis and immunosuppression, and improves survival in two different models of sepsis. IL-15 represents a potentially novel therapy of this highly lethal disorder. PMID:20026737

  13. IMPROVE THE KINETIC PERFORMANCE OF THE PUMP CONTROLLED CLAMPING UNIT IN PLASTIC INJECTION MOLDING MACHINE WITH ADAPTIVE CONTROL STRATEGY

    2006-01-01

    The kinetic characteristics of the clamping unit of plastic injection molding machine that is controlled by close loop with newly developed double speed variable pump unit are investigated.Considering the wide variation of the cylinder equivalent mass caused by the transmission ratio of clamping unit and the severe instantaneous impact force acted on the cylinder during the mold closing and opening process, an adaptive control principle of parameter and structure is proposed to improve its kinetic performance. The adaptive correlation between the acceleration feedback gain and the variable mass is derived. The pressure differential feedback is introduced to improve the dynamic performance in the case of small inertia and heavy impact load. The adaptation of sum pressure to load is used to reduce the energy loss of the system. The research results are verified by the simulation and experiment. The investigation method and the conclusions are also suitable for the differential cylinder system controlled by the traditional servo pump unit.

  14. Improved Robust Adaptive Control of a Fluidized Bed Combustor for Sewage Sludge

    MENGHong-Xia; JIAYing-Min

    2005-01-01

    This paper presents a robust model reference adaptive control scheme to deal with uncertain time delay in the dynamical model of a fluidized bed combustor for sewage sludge. The theoretical analysis and simulation results show that the proposed scheme can guarantee not only stability and robustness, but also the adaptive decoupling performance of the system.

  15. Combining spatial-temporal and phylogenetic analysis approaches for improved understanding on global H5N1 transmission.

    Lu Liang

    Full Text Available BACKGROUND: Since late 2003, the highly pathogenic influenza A H5N1 had initiated several outbreak waves that swept across the Eurasia and Africa continents. Getting prepared for reassortment or mutation of H5N1 viruses has become a global priority. Although the spreading mechanism of H5N1 has been studied from different perspectives, its main transmission agents and spread route problems remain unsolved. METHODOLOGY/PRINCIPAL FINDINGS: Based on a compilation of the time and location of global H5N1 outbreaks from November 2003 to December 2006, we report an interdisciplinary effort that combines the geospatial informatics approach with a bioinformatics approach to form an improved understanding on the transmission mechanisms of H5N1 virus. Through a spherical coordinate based analysis, which is not conventionally done in geographical analyses, we reveal obvious spatial and temporal clusters of global H5N1 cases on different scales, which we consider to be associated with two different transmission modes of H5N1 viruses. Then through an interdisciplinary study of both geographic and phylogenetic analysis, we obtain a H5N1 spreading route map. Our results provide insight on competing hypotheses as to which avian hosts are responsible for the spread of H5N1. CONCLUSIONS/SIGNIFICANCE: We found that although South China and Southeast Asia may be the virus pool of avian flu, East Siberia may be the source of the H5N1 epidemic. The concentration of migratory birds from different places increases the possibility of gene mutation. Special attention should be paid to East Siberia, Middle Siberia and South China for improved surveillance of H5N1 viruses and monitoring of migratory birds.

  16. Adaptive Lockable Units to Improve Data Availability in a Distributed Database System

    Khaled Maabreh

    2016-01-01

    Full Text Available Distributed database systems have become a phenomenon and have been considered a crucial source of information for numerous users. Users with different jobs are using such systems locally or via the Internet to meet their professional requirements. Distributed database systems consist of a number of sites connected over a computer network. Each site deals with its own database and interacts with other sites as needed. Data replication in these systems is considered a key factor in improving data availability. However, it may affect system performance when most of the transactions that access the data contain write or a mix of read and write operations because of exclusive locks and update propagation. This research proposes a new adaptive approach for increasing the availability of data contained in a distributed database system. The proposed approach suggests a new lockable unit by increasing the database hierarchy tree by one level to include attributes as lockable units instead of the entire row. This technique may allow several transactions to access the database row simultaneously by utilizing some attributes and keeping others available for other transactions. Data in a distributed database system can be accessed locally or remotely by a distributed transaction, with each distributed transaction decomposed into several sub-transactions called participants or agents. These agents access the data at multiple sites and must guarantee that any changes to the data must be committed in order to complete the main transaction. The experimental results show that using attribute-level locking will increase data availability, reliability, and throughput, as well as enhance overall system performance. Moreover, it will increase the overhead of managing such a large number of locks, which will be managed according to the qualification of the query.

  17. An Improved Method for Producing High Spatial-Resolution NDVI Time Series Datasets with Multi-Temporal MODIS NDVI Data and Landsat TM/ETM+ Images

    Yuhan Rao

    2015-06-01

    Full Text Available Due to technical limitations, it is impossible to have high resolution in both spatial and temporal dimensions for current NDVI datasets. Therefore, several methods are developed to produce high resolution (spatial and temporal NDVI time-series datasets, which face some limitations including high computation loads and unreasonable assumptions. In this study, an unmixing-based method, NDVI Linear Mixing Growth Model (NDVI-LMGM, is proposed to achieve the goal of accurately and efficiently blending MODIS NDVI time-series data and multi-temporal Landsat TM/ETM+ images. This method firstly unmixes the NDVI temporal changes in MODIS time-series to different land cover types and then uses unmixed NDVI temporal changes to predict Landsat-like NDVI dataset. The test over a forest site shows high accuracy (average difference: −0.0070; average absolute difference: 0.0228; and average absolute relative difference: 4.02% and computation efficiency of NDVI-LMGM (31 seconds using a personal computer. Experiments over more complex landscape and long-term time-series demonstrated that NDVI-LMGM performs well in each stage of vegetation growing season and is robust in regions with contrasting spatial and spatial variations. Comparisons between NDVI-LMGM and current methods (i.e., Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM, Enhanced STARFM (ESTARFM and Weighted Linear Model (WLM show that NDVI-LMGM is more accurate and efficient than current methods. The proposed method will benefit land surface process research, which requires a dense NDVI time-series dataset with high spatial resolution.

  18. Incorporating Midbrain Adaptation to Mean Sound Level Improves Models of Auditory Cortical Processing

    Harper, NS; Willmore, BDB; Schnupp, JWH; King, AJ; Schoppe, O

    2016-01-01

    Adaptation to stimulus statistics, such as the mean level and contrast of recently- heard sounds, has been demonstrated at various levels of the auditory pathway. It allows the nervous system to operate over the wide range of intensities and contrasts found in the natural world. Yet, current standard models of the response properties of auditory neurons do not incorporate such adaptation. Here, we present a model of neural responses in the ferret auditory cortex (the I...

  19. Assessing the components of adaptive capacity to improve conservation and management efforts under global change

    Nicotra, Adrienne; Beever, Erik; Robertson, Amanda; Hofmann, Gretchen; O’Leary, John

    2015-01-01

    Natural-resource managers and other conservation practitioners are under unprecedented pressure to categorize and quantify the vulnerability of natural systems based on assessment of the exposure, sensitivity, and adaptive capacity of species to climate change. Despite the urgent need for these assessments, neither the theoretical basis of adaptive capacity nor the practical issues underlying its quantification has been articulated in a manner that is directly applicable to natural-resource management. Both are critical for researchers, managers, and other conservation practitioners to develop reliable strategies for assessing adaptive capacity. Drawing from principles of classical and contemporary research and examples from terrestrial, marine, plant, and animal systems, we examined broadly the theory behind the concept of adaptive capacity. We then considered how interdisciplinary, trait- and triage-based approaches encompassing the oft-overlooked interactions among components of adaptive capacity can be used to identify species and populations likely to have higher (or lower) adaptive capacity. We identified the challenges and value of such endeavors and argue for a concerted interdisciplinary research approach that combines ecology, ecological genetics, and eco-physiology to reflect the interacting components of adaptive capacity. We aimed to provide a basis for constructive discussion between natural-resource managers and researchers, discussions urgently needed to identify research directions that will deliver answers to real-world questions facing resource managers, other conservation practitioners, and policy makers. Directing research to both seek general patterns and identify ways to facilitate adaptive capacity of key species and populations within species, will enable conservation ecologists and resource managers to maximize returns on research and management investment and arrive at novel and dynamic management and policy decisions.

  20. Rift Valley fever dynamics in Senegal: a project for pro-active adaptation and improvement of livestock raising management.

    Lafaye, Murielle; Sall, Baba; Ndiaye, Youssou; Vignolles, Cecile; Tourre, Yves M; Borchi, Franc Ois; Soubeyroux, Jean-Michel; Diallo, Mawlouth; Dia, Ibrahima; Ba, Yamar; Faye, Abdoulaye; Ba, Taibou; Ka, Alioune; Ndione, Jacques-André; Gauthier, Hélène; Lacaux, Jean-Pierre

    2013-11-01

    The multi-disciplinary French project "Adaptation à la Fiévre de la Vallée du Rift" (AdaptFVR) has concluded a 10-year constructive interaction between many scientists/partners involved with the Rift Valley fever (RVF) dynamics in Senegal. The three targeted objectives reached were (i) to produce--in near real-time--validated risk maps for parked livestock exposed to RVF mosquitoes/vectors bites; (ii) to assess the impacts on RVF vectors from climate variability at different time-scales including climate change; and (iii) to isolate processes improving local livestock management and animal health. Based on these results, concrete, pro-active adaptive actions were taken on site, which led to the establishment of a RVF early warning system (RVFews). Bulletins were released in a timely fashion during the project, tested and validated in close collaboration with the local populations, i.e. the primary users. Among the strategic, adaptive methods developed, conducted and evaluated in terms of cost/benefit analyses are the larvicide campaigns and the coupled bio-mathematical (hydrological and entomological) model technologies, which are being transferred to the staff of the "Centre de Suivi Ecologique" (CSE) in Dakar during 2013. Based on the results from the AdaptFVR project, other projects with similar conceptual and modelling approaches are currently being implemented, e.g. for urban and rural malaria and dengue in the French Antilles. PMID:24258902

  1. Evaluating spatial-temporal dynamics of net primary productivity of different forest types in northeastern China based on improved FORCCHN.

    Zhao, Junfang; Yan, Xiaodong; Guo, Jianping; Jia, Gensuo

    2012-01-01

    An improved individual-based forest ecosystem carbon budget model for China (FORCCHN) was applied to investigate the spatial-temporal dynamics of net primary productivity of different forest types in northeastern China. In this study, the forests of northeastern China were categorized into four ecological types according to their habitats and generic characteristics (evergreen broadleaf forest, deciduous broadleaf forest, evergreen needleleaf forest and deciduous needleleaf forest). The results showed that distribution and change of forest NPP in northeastern China were related to the different forest types. From 1981 to 2002, among the forest types in northeastern China, per unit area NPP and total NPP of deciduous broadleaf forest were the highest, with the values of 729.4 gC/(m(2)•yr) and 106.0 TgC/yr, respectively, followed by mixed broadleaf- needleleaf forest, deciduous needleleaf forest and evergreen needleleaf forest. From 1981 to 2002, per unit area NPP and total NPP of different forest types in northeastern China exhibited significant trends of interannual increase, and rapid increase was found between the 1980s and 1990s. The contribution of the different forest type's NPP to total NPP in northeastern China was clearly different. The greatest was deciduous broadleaf forest, followed by mixed broadleaf- needleleaf forest and deciduous needleleaf forest. The smallest was evergreen needleleaf forest. Spatial difference in NPP between different forest types was remarkable. High NPP values of deciduous needleleaf forest, mixed broadleaf- needleleaf forest and deciduous broadleaf forest were found in the Daxing'anling region, the southeastern of Xiaoxing'anling and Jilin province, and the Changbai Mountain, respectively. However, no regional differences were found for evergreen needleleaf NPP. This study provided not only an estimation NPP of different forest types in northeastern China but also a useful methodology for estimating forest carbon storage at

  2. Bolstering resilience in the coconut kingdom: Improving adaptive capacity to climate change in Vanuatu

    This communication discusses climate change adaptation efforts underway in Vanuatu. In particular, it uncovers why community-based approaches to adaptation are more likely to bear fruit than ones driven from the top-down at the national level. The authors make this claim based on early evidence that small-scale projects (a) support community ownership over adaptation, (b) provide ongoing technical learning lessons (c) relieve pressure from capacity constraints at national administrative bodies, and (d) expedite implementation by avoiding cumbersome multilateral procedures. The first section discusses its research methods and presents important characteristics of the Vanuatu economy, people and geography. The communication then moves on to discuss Vanuatu’s vulnerability to the effects of climate change. It specifically investigates on-going efforts to adapt to natural climatic hazards in Vanuatu. Early evidence and analysis reveals lessons salient for energy and climate policy. - Highlights: ► The island state of Vanuatu is especially vulnerable to natural climatic hazards and climate change. ► Community-based approaches to climate change adaptation have unique benefits in Vanuatu. ► This note provides lessons salient for energy and climate policy in Vanuatu.

  3. Improvement of the Simplified Fast Transversal Filter Type Algorithm for Adaptive Filtering

    Madjid Arezki

    2009-01-01

    Full Text Available Problem statement: In this study, we proposed a new algorithm M-SMFTF for adaptive filtering with fast convergence and low complexity. Approach: It was the result of a simplified FTF type algorithm, where the adaptation gain was obtained only from the forward prediction variables and using a new recursive method to compute the likelihood variable. Results: The computational complexity was reduced from 7L-6L, where L is the finite impulse response filter length. Furthermore, this computational complexity can be significantly reduced to (2L+4P when used with a reduced P-size forward predictor. Conclusion: This algorithm presented a certain interest, for the adaptation of very long filters, like those used in the problems of echo acoustic cancellation, due to its reduced complexity, its numerical stability and its convergence in the presence of the speech signal.

  4. Application of Improved Neural Adaptive PSD Algorithm in Temperature Control of INS

    缪玲娟; 郭振西; 崔燕

    2004-01-01

    A neural adaptive proportion sum differential (PSD) algorithm with errors prediction is researched. It is applied in inertial navigation system(INS) temperature control. The algorithm do not need the process's precise mathematical model and can adapt to the process pareters changing, and can deal with the process with nonlinearity. According to the Smith predictor, author developed a method that takes the predicted process error and error change as neural adaptive PSD algorithm's input. The method is effective to the system with long dead time. The results of compute simulation show that this system has characters of quickly reaction, low overshoot and good stability. It can meet the requirements of temperature control of INS.

  5. Adaption of the Cytokinesis-Block Micronucleus Cytome Assay for Improved Triage Biodosimetry.

    Beinke, C; Port, M; Riecke, A; Ruf, C G; Abend, M

    2016-05-01

    The purpose of this work was to adapt a more advanced form of the cytokinesis-block micronucleus (CBMN) cytome assay for triage biodosimetry in the event of a mass casualty radiation incident. We modified scoring procedures for the CBMN cytome assay to optimize field deployability, dose range, accuracy, speed, economy, simplicity and stability. Peripheral blood of 20 donors was irradiated in vitro (0-6 Gy X ray, maximum photon energy 240 keV) and processed for CBMN. Initially, we assessed two manual scoring strategies for accuracy: 1. Conventional scoring, comprised of micronucleus (MN) frequency per 1,000 binucleated (BN) cells (MN/1,000 BN cells); and 2. Evaluation of 1,000, 2,000 and 3,000 cells in total and different cellular subsets based on MN formation and proliferation (e.g., BN cells with and without MN, mononucleated cells). We used linear and logistic regression models to identify the cellular subsets related closest to dose with the best discrimination ability among different doses/dose categories. We validated the most promising subsets and their combinations with 16 blind samples covering a dose range of 0-8.3 Gy. Linear dose-response relationships comparable to the conventional CBMN assay (r(2) = 0.86) were found for BN cells with MN (r(2) = 0.84) and BN cells without MN (r(2) = 0.84). Models of combined cell counts (CCC) of BN cells with and without MN (BN(+MN) and BN(-MN)) with mononucleated cells (Mono) improved this relationship (r(2) = 0.92). Conventional CBMN discriminated dose categories up to 3 Gy with a concordance between 0.96-1.0 upon scoring 1,000 total cells. In 1,000 BN cells, concordances were observed for conventional CBMN up to 4 Gy as well as BN(+MN) or BN(-MN) (about 0.85). At doses of 4-6 Gy, the concordance of conventional CBMN, BN(+MN) and BN(-MN) declined (about 0.55). We found about 20% higher concordance and more precise dose estimates of irradiated and blinded samples for CCC (Mono + BN(+MN)) after scoring 1,000 total cells

  6. Managing project complexity: A study into adapting early project phases to improve project performance in large engineering projects

    Bosch-Rekveldt, M.G.C.

    2011-01-01

    Engineering projects become increasingly more complex and project complexity is assumed to be one of the causes for projects being delivered late and over budget. However, what this project complexity actually comprised of was unclear. To improve the overall project performance, this study focuses on identifying the potential causes of complexity in projects. Moreover, it is investigated how the early project phase could be adapted to the complexity of the project. The research is performed w...

  7. Efficiency and reliability improvement in wind turbine converters by grid converter adaptive control

    Trintis, Ionut; Munk-Nielsen, Stig; Abrahamsen, Flemming;

    2013-01-01

    and generator side. Operating in this way, the electrical and thermal stress factors are decreased on the power electronic devices, increasing their lifetime. The simulation results using this method show efficiency increase and devices temperature cycles slightly decreased. Experimental results on a...... wind turbine power stack shows efficiency increase in the high power region.......This paper presents a control method that reduces the losses in wind turbine converters adaptively controlling the grid converter. The dc-link voltage adapts its reference based on the system state and therefore reduces the stored energy, and is therefore kept at the minimum necessary for the grid...

  8. Simulation of Adaptive OFDM and its improved algorithm%自适应OFDM及其改进算法

    郝丽娜; 宋金玲

    2011-01-01

    OFDM 技术是第四代移动通信的核心技术之一,是一种高效的数据传输方式,是一种特殊的多载波传输方案。本文介绍的改进后的自适应调制技术,自适应地根据星座图集所限定的比特数目来进行变步长调整,这样大大减少了计算量。并通过使用Matlab仿真出的结果与Campello算法仿真的结果进行比较,说明改进后的变步长的自适应OFDM算法的优越性。%OFDM technology is one of the core technologies of the fourth generation mobile communication, which is an efficient data transmission and is a special multi-carrier transmission scheme. The improved adaptive modulation technology adjusts the step of computing according to limited bits of constellation atlas, which reduce the computation greatly. Compared the result of the improved adaptive modulation technology with the result of Compello algorithm simulation, we find that the improved adaptive modulation OFDM technology has great advantages.

  9. Forecasting foreign exchange rates with an improved back-propagation learning algorithm with adaptive smoothing momentum terms

    Lean YU; Shouyang WANG; Kin Keung LAI

    2009-01-01

    The slow convergence of back-propagation neu-ral network (BPNN) has become a challenge in data-mining and knowledge discovery applications due to the drawbacks of the gradient descent (GD) optimization method, which is widely adopted in BPNN learning. To solve this problem,some standard Optimization techniques such as conjugate-gradient and Newton method have been proposed to improve the convergence rate of BP learning algorithm. This paper presents a heuristic method that adds an adaptive smooth-ing momentum term to original BP learning algorithm to speedup the convergence. In this improved BP learning al-gorithm, adaptive smoothing technique is used to adjust the momentums of weight updating formula automatically in terms of "3 σ limits theory." Using the adaptive smoothing momentum terms, the improved BP learning algorithm can make the network training and convergence process faster,and the network's generalization performance stronger than the standard BP learning algorithm can do. In order to ver-ify the effectiveness of the proposed BP learning algorithm,three typical foreign exchange rates, British pound (GBP),Euro (EUR), and Japanese yen (JPY), are chosen as the fore-casting targets for illustration purpose. Experimental results from homogeneous algorithm comparisons reveal that the proposed BP learning algorithm outperforms the other com-parable BP algorithms in performance and convergence rate.Furthermore, empirical results from heterogeneous model comparisons also show the effectiveness of the proposed BP learning algorithm.

  10. Identification of robust adaptation gene regulatory network parameters using an improved particle swarm optimization algorithm.

    Huang, X N; Ren, H P

    2016-01-01

    Robust adaptation is a critical ability of gene regulatory network (GRN) to survive in a fluctuating environment, which represents the system responding to an input stimulus rapidly and then returning to its pre-stimulus steady state timely. In this paper, the GRN is modeled using the Michaelis-Menten rate equations, which are highly nonlinear differential equations containing 12 undetermined parameters. The robust adaption is quantitatively described by two conflicting indices. To identify the parameter sets in order to confer the GRNs with robust adaptation is a multi-variable, multi-objective, and multi-peak optimization problem, which is difficult to acquire satisfactory solutions especially high-quality solutions. A new best-neighbor particle swarm optimization algorithm is proposed to implement this task. The proposed algorithm employs a Latin hypercube sampling method to generate the initial population. The particle crossover operation and elitist preservation strategy are also used in the proposed algorithm. The simulation results revealed that the proposed algorithm could identify multiple solutions in one time running. Moreover, it demonstrated a superior performance as compared to the previous methods in the sense of detecting more high-quality solutions within an acceptable time. The proposed methodology, owing to its universality and simplicity, is useful for providing the guidance to design GRN with superior robust adaptation. PMID:27323043

  11. The Contextualized Technology Adaptation Process (CTAP): Optimizing Health Information Technology to Improve Mental Health Systems.

    Lyon, Aaron R; Wasse, Jessica Knaster; Ludwig, Kristy; Zachry, Mark; Bruns, Eric J; Unützer, Jürgen; McCauley, Elizabeth

    2016-05-01

    Health information technologies have become a central fixture in the mental healthcare landscape, but few frameworks exist to guide their adaptation to novel settings. This paper introduces the contextualized technology adaptation process (CTAP) and presents data collected during Phase 1 of its application to measurement feedback system development in school mental health. The CTAP is built on models of human-centered design and implementation science and incorporates repeated mixed methods assessments to guide the design of technologies to ensure high compatibility with a destination setting. CTAP phases include: (1) Contextual evaluation, (2) Evaluation of the unadapted technology, (3) Trialing and evaluation of the adapted technology, (4) Refinement and larger-scale implementation, and (5) Sustainment through ongoing evaluation and system revision. Qualitative findings from school-based practitioner focus groups are presented, which provided information for CTAP Phase 1, contextual evaluation, surrounding education sector clinicians' workflows, types of technologies currently available, and influences on technology use. Discussion focuses on how findings will inform subsequent CTAP phases, as well as their implications for future technology adaptation across content domains and service sectors. PMID:25677251

  12. Building Turnaround Capacity for Urban School Improvement: The Role of Adaptive Leadership and Defined Autonomy

    Conrad, Jill K.

    2013-01-01

    This dissertation examines the levels of and relationships between technical leadership, adaptive leadership, and defined autonomy among Denver school leaders along with their combined effects on school growth gains over time. Thirty principals provided complete responses to an online survey that included existing scales for technical leadership,…

  13. FOG Random Drift Signal Denoising Based on the Improved AR Model and Modified Sage-Husa Adaptive Kalman Filter.

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

    2016-01-01

    In order to reduce the influence of fiber optic gyroscope (FOG) random drift error on inertial navigation systems, an improved auto regressive (AR) model is put forward in this paper. First, based on real-time observations at each restart of the gyroscope, the model of FOG random drift can be established online. In the improved AR model, the FOG measured signal is employed instead of the zero mean signals. Then, the modified Sage-Husa adaptive Kalman filter (SHAKF) is introduced, which can directly carry out real-time filtering on the FOG signals. Finally, static and dynamic experiments are done to verify the effectiveness. The filtering results are analyzed with Allan variance. The analysis results show that the improved AR model has high fitting accuracy and strong adaptability, and the minimum fitting accuracy of single noise is 93.2%. Based on the improved AR(3) model, the denoising method of SHAKF is more effective than traditional methods, and its effect is better than 30%. The random drift error of FOG is reduced effectively, and the precision of the FOG is improved. PMID:27420062

  14. FOG Random Drift Signal Denoising Based on the Improved AR Model and Modified Sage-Husa Adaptive Kalman Filter

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

    2016-01-01

    In order to reduce the influence of fiber optic gyroscope (FOG) random drift error on inertial navigation systems, an improved auto regressive (AR) model is put forward in this paper. First, based on real-time observations at each restart of the gyroscope, the model of FOG random drift can be established online. In the improved AR model, the FOG measured signal is employed instead of the zero mean signals. Then, the modified Sage-Husa adaptive Kalman filter (SHAKF) is introduced, which can directly carry out real-time filtering on the FOG signals. Finally, static and dynamic experiments are done to verify the effectiveness. The filtering results are analyzed with Allan variance. The analysis results show that the improved AR model has high fitting accuracy and strong adaptability, and the minimum fitting accuracy of single noise is 93.2%. Based on the improved AR(3) model, the denoising method of SHAKF is more effective than traditional methods, and its effect is better than 30%. The random drift error of FOG is reduced effectively, and the precision of the FOG is improved. PMID:27420062

  15. Dual-thread parallel control strategy for ophthalmic adaptive optics

    Yu, Yongxin; Zhang, Yuhua

    2014-01-01

    To improve ophthalmic adaptive optics speed and compensate for ocular wavefront aberration of high temporal frequency, the adaptive optics wavefront correction has been implemented with a control scheme including 2 parallel threads; one is dedicated to wavefront detection and the other conducts wavefront reconstruction and compensation. With a custom Shack-Hartmann wavefront sensor that measures the ocular wave aberration with 193 subapertures across the pupil, adaptive optics has achieved a ...

  16. Single breath-hold real-time cine MR imaging: improved temporal resolution using generalized autocalibrating partially parallel acquisition (GRAPPA) algorithm

    The purpose of this study was to test parallel imaging techniques for improvement of temporal resolution in multislice single breath-hold real-time cine steady-state free precession (SSFP) in comparison with standard segmented single-slice SSFP techniques. Eighteen subjects were examined on a 1.5-T scanner using a multislice real-time cine SSFP technique using the GRAPPA algorithm. Global left ventricular parameters (EDV, ESV, SV, EF) were evaluated and results compared with a standard segmented single-slice SSFP technique. Results for EDV (r=0.93), ESV (r=0.99), SV (r=0.83), and EF (r=0.99) of real-time multislice SSFP imaging showed a high correlation with results of segmented SSFP acquisitions. Systematic differences between both techniques were statistically non-significant. Single breath-hold multislice techniques using GRAPPA allow for improvement of temporal resolution and for accurate assessment of global left ventricular functional parameters. (orig.)

  17. Improving the performance of link prediction by adaptively exploiting multiple structural features of networks

    Ma, Chuang; Zhang, Hai-Feng

    2016-01-01

    So far, many network-structure-based link prediction methods have been proposed. However, these traditional methods were proposed by highlighting one or two structural features of networks, and then use the methods to implement link prediction in different networks. In many cases, the performance is not ideal since each network has its unique underlying structural features. In this article, by analyzing different real networks, we find that the structural features of different networks are remarkably different. In particular, even in the same networks, their inner structural features are utterly different. Inspired by these facts, an \\emph{adaptive} link prediction method is proposed to incorporate multiple structural features from the perspective of combination optimization. In the model, the weight of each structural feature is \\emph{adaptively } determined by logistic regression but not be artificially given in advance. According to our experimental results, we find that the logistic regression based link ...

  18. Context-based service adaptation platform: Improving the user experience towards mobile location services

    Schou, Saowanee

    Back in 2000 and the, following two or three years, mobile location services gained a great deal of interest and they were considered as one of the few service categories where users would be willing to pay for the usage. Since 2000 countless mobile location services have been launched in different...... parts of the world. However, the mobile location services have obviously not yet met the hyped expectation of mass-market adoption that was expressed in 2000. The lack of adaptability and offerings tailored to different user requirements in specific contexts of use is one of the factors inhibiting the...... take-off of the existing mobile location services both in Asia and Western Europe. Adaptability is envisioned by Wireless World Research Forum (WWRF) as one of the keys to the success of any service beyond year 2010 and one of the service capabilities that should be made available on the next...

  19. Adaptive Representations for Improving Evolvability, Parameter Control, and Parallelization of Gene Expression Programming

    Nigel P. A. Browne

    2010-01-01

    Full Text Available Gene Expression Programming (GEP is a genetic algorithm that evolves linear chromosomes encoding nonlinear (tree-like structures. In the original GEP algorithm, the genome size is problem specific and is determined through trial and error. In this work, a method for adaptive control of the genome size is presented. The approach introduces mutation, transposition, and recombination operators that enable a population of heterogeneously structured chromosomes, something the original GEP algorithm does not support. This permits crossbreeding between normally incompatible individuals, speciation within a population, increases the evolvability of the representations, and enhances parallel GEP. To test our approach, an assortment of problems were used, including symbolic regression, classification, and parameter optimization. Our experimental results show that our approach provides a solution for the problem of self-adaptive control of the genome size of GEP's representation.

  20. Aortic pressure wave reconstruction during exercise is improved by adaptive filtering: a pilot study

    Stok, W.J.; Westerhof, B E; Guelen, I.; Karemaker, J. M.

    2011-01-01

    Reconstruction of central aortic pressure from a peripheral measurement by a generalized transfer function (genTF) works well at rest and mild exercise at lower heart rates, but becomes less accurate during heavy exercise. Particularly, systolic and pulse pressure estimations deteriorate, thereby underestimating central pressure. We tested individualization of the TF (indTF) by adapting its resonance frequency at the various levels of exercise. In seven males (age 44–57) with coronary artery ...

  1. Improving Inpatient Surveys: Web-Based Computer Adaptive Testing Accessed via Mobile Phone QR Codes

    Chien, Tsair-Wei; Lin, Weir-Sen

    2016-01-01

    Background The National Health Service (NHS) 70-item inpatient questionnaire surveys inpatients on their perceptions of their hospitalization experience. However, it imposes more burden on the patient than other similar surveys. The literature shows that computerized adaptive testing (CAT) based on item response theory can help shorten the item length of a questionnaire without compromising its precision. Objective Our aim was to investigate whether CAT can be (1) efficient with item reductio...

  2. Studying citizen science through adaptive management and learning feedbacks as mechanisms for improving conservation.

    Jordan, Rebecca; Gray, Steven; Sorensen, Amanda; Newman, Greg; Mellor, David; Newman, Greg; Hmelo-Silver, Cindy; LaDeau, Shannon; Biehler, Dawn; Crall, Alycia

    2016-06-01

    Citizen science has generated a growing interest among scientists and community groups, and citizen science programs have been created specifically for conservation. We examined collaborative science, a highly interactive form of citizen science, which we developed within a theoretically informed framework. In this essay, we focused on 2 aspects of our framework: social learning and adaptive management. Social learning, in contrast to individual-based learning, stresses collaborative and generative insight making and is well-suited for adaptive management. Adaptive-management integrates feedback loops that are informed by what is learned and is guided by iterative decision making. Participants engaged in citizen science are able to add to what they are learning through primary data collection, which can result in the real-time information that is often necessary for conservation. Our work is particularly timely because research publications consistently report a lack of established frameworks and evaluation plans to address the extent of conservation outcomes in citizen science. To illustrate how our framework supports conservation through citizen science, we examined how 2 programs enacted our collaborative science framework. Further, we inspected preliminary conservation outcomes of our case-study programs. These programs, despite their recent implementation, are demonstrating promise with regard to positive conservation outcomes. To date, they are independently earning funds to support research, earning buy-in from local partners to engage in experimentation, and, in the absence of leading scientists, are collecting data to test ideas. We argue that this success is due to citizen scientists being organized around local issues and engaging in iterative, collaborative, and adaptive learning. PMID:26585836

  3. Adaptive protein evolution grants organismal fitness by improving catalysis and flexibility

    Tomatis, Pablo E.; Fabiane, Stella M.; Simona, Fabio; Carloni, Paolo; Sutton, Brian J.; Vila, Alejandro J.

    2008-01-01

    Protein evolution is crucial for organismal adaptation and fitness. This process takes place by shaping a given 3-dimensional fold for its particular biochemical function within the metabolic requirements and constraints of the environment. The complex interplay between sequence, structure, functionality, and stability that gives rise to a particular phenotype has limited the identification of traits acquired through evolution. This is further complicated by the fact that mutations are pleiot...

  4. Adaptive High-Bandwidth Digitally Controlled Buck Converter with Improved Line and Load Transient Response

    Lee, ATL; Sin, JKO; Chan, PCH

    2014-01-01

    Digitally controlled switching converter suffers from bandwidth limitation because of the additional phase delay in the digital feedback control loop. In order to overcome the bandwidth limitation without using a high sampling rate, this paper presents an adaptive third-order digital controller for regulating a voltage-mode buck converter with a modest 2x oversampling ratio. The phase lag due to the ADC conversion time delay is virtually compensated by providing an early estimation of the err...

  5. Adaptive Critic Based Neuro-Fuzzy Tracker for Improving Conversion Efficiency in PV Solar Cells

    Halimeh Rashidi; Saeed Niazi; Jamshid Khorshidi

    2012-01-01

    The output power of photovoltaic systems is directly related to the amount of solar energy collected by the system and it is therefore necessary to track the sun’s position with high accuracy. This study proposes multi-agent adaptive critic based nero fuzzy solar tracking system dedicated to PV panels. The proposed tracker ensures the optimal conversion of solar energy into electricity by properly adjusting the PV panels according to the position of the sun. To evaluate the usefulness of the ...

  6. An Improved QoS Multipath Routing Using Bandwidth Estimation and Rate Adaptation

    S. Suganya

    2014-06-01

    Full Text Available Mobile Adhoc Networks (MANETs are composed of nodes which communicate with one another without network infrastructure. Their advantage being that they can be used in isolation or along with wired infrastructure, usually via a gateway node to ensure traffic relay for both networks. Quality of Service (QoS is harder to ensure in ad hoc networks than in other network types, as wireless bandwidth is shared by adjacent nodes with network topology changing as nodes move. Most QoS protocols are implemented for specific scenarios and consider parameters such as network topologies, bandwidth, mobility, security and so on. This work proposes a novel multipath routing protocol which is an extension of AOMDV by discovering routes based on available bandwidth and rate adaptation. The method with Hello message box is used to calculate available bandwidth for a route. Relative Fairness and Optimized Throughput is an approach for rate adaptation in this paper which is to ensure fairness and allow nodes to adapt transmission rates and contention windows to channel quality. In sequence this is determined by calculating the access probability of a channel for each node in a distributed manner approximating successful and failed transmissions.

  7. Improving traffic flow at a 2-to-1 lane reduction with wirelessly connected, adaptive cruise control vehicles

    Davis, L C

    2015-01-01

    Wirelessly connected vehicles that exchange information about traffic conditions can reduce delays caused by congestion. At a 2-to-1 lane reduction, the improvement in flow past a bottleneck due to traffic with a random mixture of 40% connected vehicles is found to be 52%. Control is based on connected-vehicle-reported velocities near the bottleneck. In response to indications of congestion the connected vehicles, which are also adaptive cruise control vehicles, reduce their speed in slowdown regions. Early lane changes of manually driven vehicles from the terminated lane to the continuous lane are induced by the slowing connected vehicles. Self-organized congestion at the bottleneck is thus delayed or eliminated, depending upon the incoming flow magnitude. For the large majority of vehicles, travel times past the bottleneck are substantially reduced. Control is responsible for delaying the onset of congestion as the incoming flow increases. Adaptive cruise control increases the flow out of the congested stat...

  8. A Novel Clinical Decision Support System Using Improved Adaptive Genetic Algorithm for the Assessment of Fetal Well-Being

    Sindhu Ravindran

    2015-01-01

    Full Text Available A novel clinical decision support system is proposed in this paper for evaluating the fetal well-being from the cardiotocogram (CTG dataset through an Improved Adaptive Genetic Algorithm (IAGA and Extreme Learning Machine (ELM. IAGA employs a new scaling technique (called sigma scaling to avoid premature convergence and applies adaptive crossover and mutation techniques with masking concepts to enhance population diversity. Also, this search algorithm utilizes three different fitness functions (two single objective fitness functions and multi-objective fitness function to assess its performance. The classification results unfold that promising classification accuracy of 94% is obtained with an optimal feature subset using IAGA. Also, the classification results are compared with those of other Feature Reduction techniques to substantiate its exhaustive search towards the global optimum. Besides, five other benchmark datasets are used to gauge the strength of the proposed IAGA algorithm.

  9. Checking performance of field corn inbreds as donors of favorable alleles to improve early vigor and adaptation of sweet corn hybrids to european conditions

    Malvar Pintos, Rosa Ana; Revilla Temiño, Pedro; Cartea González, María Elena; Butrón Gómez, Ana María; Ordás Pérez, Amando

    2001-01-01

    Field corn inbreds adapted to the European Atlantic coast are being used to improve early vigor and adaptation of sweet corn. In a previous work, we used the methods of identifying field corn inbred lines for use in improving parents of sweet corn single crosses, and we predicted that EP42 was the best potential donor of favorable alleles for improving early vigor and adaptation of V679 x EP60 and 15125 x EP60, followed by A632, and w64A. Our objective was to compare realized results with pre...

  10. Context-based service adaptation platform: Improving the user experience towards mobile location services

    Schou, Saowanee

    2008-01-01

    Back in 2000 and the, following two or three years, mobile location services gained a great deal of interest and they were considered as one of the few service categories where users would be willing to pay for the usage. Since 2000 countless mobile location services have been launched in different...... parts of the world. However, the mobile location services have obviously not yet met the hyped expectation of mass-market adoption that was expressed in 2000. The lack of adaptability and offerings tailored to different user requirements in specific contexts of use is one of the factors inhibiting the...

  11. Decentralised nonlinear equilibrium point adaptive control of generator for improving multimachine power system transient stability

    Wu, J.; Yokoyama, A. [Tokyo Univ., Tokyo (Japan); Lu, Q. [TsingHua Univ., Tsinghua (China); Goto, M. [Nagoya Univ., Nagoya (Japan); Konishi, H. [Hitachi Ltd. (Japan)

    2003-11-01

    Decentralised nonlinear control of generator excitation and turbine governor based on the feedback linearization approach is proposed. To make the proposed nonlinear control possess adaptive ability under the changing conditions of power systems, the extended observation decoupled state space in which mechanical power is considered as variable is proposed, and the local stability of the post fault equilibrium point is established rigorously from a mathematical viewpoint. Nonlinear simulations are performed in a three-machine power system and in the ten-machine West Japan power system, and the effectiveness of the proposed nonlinear control and the convergence characteristics of the post fault equilibrium point observer are validated. (Author)

  12. Adaptive Learning and Thinking Style to Improve E-Learning Environment Using Neural Network (ALTENN) Model

    Dagez, Hanan Ettaher; Ambarka, Ali Elghali

    2015-01-01

     In recent years we have witnessed an increasingly heightened awareness of the potential benefits of adaptively in e-learning. This has been mainly driven by the realization that the ideal of individualized learning (i.e., learning tailored to the specific requirements and preferences of the individual) cannot be achieved, especially at a “massive” scale, using traditional approaches. In e-learning when the learning style of the student is not compatible with the teaching style of the teacher...

  13. Automated interferometric synthetic aperture microscopy and computational adaptive optics for improved optical coherence tomography.

    Xu, Yang; Liu, Yuan-Zhi; Boppart, Stephen A; Carney, P Scott

    2016-03-10

    In this paper, we introduce an algorithm framework for the automation of interferometric synthetic aperture microscopy (ISAM). Under this framework, common processing steps such as dispersion correction, Fourier domain resampling, and computational adaptive optics aberration correction are carried out as metrics-assisted parameter search problems. We further present the results of this algorithm applied to phantom and biological tissue samples and compare with manually adjusted results. With the automated algorithm, near-optimal ISAM reconstruction can be achieved without manual adjustment. At the same time, the technical barrier for the nonexpert using ISAM imaging is also significantly lowered. PMID:26974799

  14. Adaptive feedforward of estimated ripple improves the closed loop system performance significantly

    The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of Acceleration Production of Tritium (APT) accelerator. This paper addresses the problem of LLRF control system for LEDA. The authors propose an estimator of the ripple and its time derivative and a control law which is based on PID control and adaptive feedforward of estimated ripple. The control law reduces the effect of the deterministic cathode ripple that is due to high voltage power supply and achieves tracking of desired set points

  15. Improve earthquake hypocenter using adaptive simulated annealing inversion in regional tectonic, volcano tectonic, and geothermal observation

    Ry, Rexha Verdhora, E-mail: rexha.vry@gmail.com [Master Program of Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesha No.10, Bandung 40132 (Indonesia); Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id [Global Geophysical Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesha No.10, Bandung 40132 (Indonesia)

    2015-04-24

    Observation of earthquakes is routinely used widely in tectonic activity observation, and also in local scale such as volcano tectonic and geothermal activity observation. It is necessary for determining the location of precise hypocenter which the process involves finding a hypocenter location that has minimum error between the observed and the calculated travel times. When solving this nonlinear inverse problem, simulated annealing inversion method can be applied to such global optimization problems, which the convergence of its solution is independent of the initial model. In this study, we developed own program codeby applying adaptive simulated annealing inversion in Matlab environment. We applied this method to determine earthquake hypocenter using several data cases which are regional tectonic, volcano tectonic, and geothermal field. The travel times were calculated using ray tracing shooting method. We then compared its results with the results using Geiger’s method to analyze its reliability. Our results show hypocenter location has smaller RMS error compared to the Geiger’s result that can be statistically associated with better solution. The hypocenter of earthquakes also well correlated with geological structure in the study area. Werecommend using adaptive simulated annealing inversion to relocate hypocenter location in purpose to get precise and accurate earthquake location.

  16. Improve earthquake hypocenter using adaptive simulated annealing inversion in regional tectonic, volcano tectonic, and geothermal observation

    Observation of earthquakes is routinely used widely in tectonic activity observation, and also in local scale such as volcano tectonic and geothermal activity observation. It is necessary for determining the location of precise hypocenter which the process involves finding a hypocenter location that has minimum error between the observed and the calculated travel times. When solving this nonlinear inverse problem, simulated annealing inversion method can be applied to such global optimization problems, which the convergence of its solution is independent of the initial model. In this study, we developed own program codeby applying adaptive simulated annealing inversion in Matlab environment. We applied this method to determine earthquake hypocenter using several data cases which are regional tectonic, volcano tectonic, and geothermal field. The travel times were calculated using ray tracing shooting method. We then compared its results with the results using Geiger’s method to analyze its reliability. Our results show hypocenter location has smaller RMS error compared to the Geiger’s result that can be statistically associated with better solution. The hypocenter of earthquakes also well correlated with geological structure in the study area. Werecommend using adaptive simulated annealing inversion to relocate hypocenter location in purpose to get precise and accurate earthquake location

  17. Spatio-Temporal Population Distribution and Evacuation Modeling for Improving Tsunami Risk Assessment in the Lisbon Metropolitan Area

    Freire, Sergio; Aubrecht, Christoph; Wegscheider, Stephanie

    2011-01-01

    Lisbon, Portugal, is subject to significant risk of tsunami, and was hit by a very destructive earthquake-triggered tsunami during daytime in 1755. The Regional Plan for Territorial Management for the Lisbon Metropolitan Area (PROT), under discussion, includes a tsunami hazard map, showing that significant urbanized areas may be at risk of inundation. In order to consider the time dependence of population exposure to tsunami threats, we map and analyze the spatio-temporal population distri...

  18. Cultural adaptation of an evidence-based nursing intervention to improve medication adherence among people living with HIV/AIDS (PLWHA) in China

    Williams, Ann B.; Wang, Honghong; Burgess, Jane; Li, Xianhong; Danvers, Karina

    2012-01-01

    BACKGROUND Adapting nursing interventions to suit the needs and culture of a new population (cultural adaptation) is an important early step in the process of implementation and dissemination. While the need for cultural adaptation is widely accepted, research-based strategies for doing so are not well articulated. Non-adherence to medications for chronic disease is a global problem and cultural adaptation of existing evidence-based interventions could be useful. OBJECTIVES This paper aims to describe the cultural adaptation of an evidence-based nursing intervention to improve medication adherence among people living with HIV/AIDS and to offer recommendations for adaptation of interventions across cultures and borders. SITE The intervention, which demonstrated efficacy in a randomized controlled trial in North America, was adapted for the cultural and social context of Hunan Province, in south central China. SOURCES OF DATA The adaptation process was undertaken by intervention stakeholders including the original intervention study team, the proposed adaptation team, and members of a Community Advisory Board, including people living with HIV/AIDS, family members, and health care workers at the target clinical sites. PROCEDURES The adaptation process was driven by quantitative and qualitative data describing the new population and context and was guided by principles for cultural adaptation drawn from prevention science research. RESULTS The primary adaptation to the intervention was the inclusion of family members in intervention activities, in response to the cultural and social importance of the family in rural China. In a pilot test of the adapted intervention, self-reported medication adherence improved significantly in the group receiving the intervention compared to the control group (p=0.01). Recommendations for cultural adaptation of nursing interventions include 1) involve stakeholders from the beginning; 2) assess the population, need, and context; 3

  19. Species adaptability, seed availability and prospects for improvement of eucalyptus in Minas Gerais

    Ferrevia, M.; Balloni, E.A.; Pinto, J.E. Jr.; Jacob, W.S.

    1978-01-01

    As part of a continuing study into possible improvement of Eucalyptus spp. in plantations, data are presented from all existing trials and experimental plantings in Minas Gerais, Brazil. Growth, uniformity, form and fruiting are indicated.

  20. Improved MR Brain Image Segmentation Using Adaptive Gabor Filtering Scheme with Fuzzy C-Means Algorithm

    P. Hari Krishnan

    2014-08-01

    Full Text Available Image segmentation is the foremost process in medical image processing. It aids the diagnostic and clinical analysis of MRI (Magnetic Resonance Imaging images that were acquired through the most complex procedures of medical diagnostics. The earliest soft computing techniques in segmenting images were carried out through Fuzzy C-Means (FCM and similar extensions of various clustering algorithms. In this paper, we introduced an innovative method that uses Gabor energy filter with adaptive features to pre-extract the information of various regions of a brain image, obtained either from a MRI or CT scanner. The noise-reduced image with blurred features was then made to undergo modifications by applying unsupervised learning methods such as FCM technique, whose output has efficient exclusion of certain strength of noise elements resulting in better classified pixels.

  1. Adapting diagrams from physics textbooks: improving the autonomy of blind students

    Dickman, Adriana; Martins, Alexandre; Ferreira, Amauri

    2014-03-01

    In this work we elaborate and test a glossary consisting of a set of objects and their symbols. The symbols are designed to represent objects frequently used in mechanics diagrams, such as vectors, ropes, pulleys, blocks and surfaces, and can be used to adapt drawings of physics situations in textbooks for blind high school students. The educational product was tested at a specialized school for the blind. The results indicate that adequate training can help blind students to become familiar with the symbols, and to identify them in a problem without the need of a description. This educational product can help blind students to achieve the same conditions of autonomy as sighted ones, when studying physics. Research supported by CNPq, Capes, Fapemig and FIP/PUC-MG (Brazil).

  2. Adaptive Critic Based Neuro-Fuzzy Tracker for Improving Conversion Efficiency in PV Solar Cells

    Halimeh Rashidi

    2012-08-01

    Full Text Available The output power of photovoltaic systems is directly related to the amount of solar energy collected by the system and it is therefore necessary to track the sun’s position with high accuracy. This study proposes multi-agent adaptive critic based nero fuzzy solar tracking system dedicated to PV panels. The proposed tracker ensures the optimal conversion of solar energy into electricity by properly adjusting the PV panels according to the position of the sun. To evaluate the usefulness of the proposed method, some computer simulations are performed and compared with fuzzy PD controller. Obtained results show the proposed control strategy is very robust, flexible and could be used to get the desired performance levels. The response time is also very fast. Simulation results that have been compared with fuzzy PD controller show that our method has the better control performance than fuzzy PD controller.

  3. Improving traffic flow at a 2-to-1 lane reduction with wirelessly connected, adaptive cruise control vehicles

    Davis, L. C.

    2016-06-01

    Wirelessly connected vehicles that exchange information about traffic conditions can reduce delays caused by congestion. At a 2-to-1 lane reduction, the improvement in flow past a bottleneck due to traffic with a random mixture of 40% connected vehicles is found to be 52%. Control is based on connected-vehicle-reported velocities near the bottleneck. In response to indications of congestion the connected vehicles, which are also adaptive cruise control vehicles, reduce their speed in slowdown regions. Early lane changes of manually driven vehicles from the terminated lane to the continuous lane are induced by the slowing connected vehicles. Self-organized congestion at the bottleneck is thus delayed or eliminated, depending upon the incoming flow magnitude. For the large majority of vehicles, travel times past the bottleneck are substantially reduced. Control is responsible for delaying the onset of congestion as the incoming flow increases. Adaptive cruise control increases the flow out of the congested state at the bottleneck. The nature of the congested state, when it occurs, appears to be similar under a variety of conditions. Typically 80-100 vehicles are approximately equally distributed between the lanes in the 500 m region prior to the end of the terminated lane. Without the adaptive cruise control capability, connected vehicles can delay the onset of congestion but do not increase the asymptotic flow past the bottleneck. Calculations are done using the Kerner-Klenov three-phase theory, stochastic discrete-time model for manual vehicles. The dynamics of the connected vehicles is given by a conventional adaptive cruise control algorithm plus commanded deceleration. Because time in the model for manual vehicles is discrete (one-second intervals), it is assumed that the acceleration of any vehicle immediately in front of a connected vehicle is constant during the time interval, thereby preserving the computational simplicity and speed of a discrete-time model.

  4. Improvement of early vigor and adaptation of sweet corn to the European Atlantic coast with open-pollinated field corn populations

    Cartea González, María Elena; Malvar Pintos, Rosa Ana; Revilla Temiño, Pedro; Ordás Pérez, Amando

    1996-01-01

    Sweet corn lacks early vigor and is poorly adapted to the environmental conditions of the European Atlantic coast. New sources of germplasm for improving early vigor and other agronomic traits would be useful. Environmental conditions in the Northwest of Spain, as in the European Atlantic coast, are characterized by humid cool springs and short growing seasons. The objectives of this study were to evaluate ten field corn populations to improve the adaptability of sweet corn to the environment...

  5. An Improved Character Segmentation Algorithm Based on Local Adaptive Thresholding Technique for Chinese NvShu Documents

    Yangguang Sun

    2014-06-01

    Full Text Available For the structural characteristics of Chinese NvShu character, by combining the basic idea in LLT local threshold algorithm and introducing the maximal between-class variance algorithm into local windows, an improved character segmentation algorithm based on local adaptive thresholding technique for Chinese NvShu documents was presented in this paper. Because of designing the corresponding correction parameters for the threshold and using secondary search mechanism, our proposed method could not only automatically obtain local threshold, but also avoid the loss of the character image information and improve the accuracy of the character image segmentation. Experimental results demonstrated its capability to reduce the effect of background noise, especially for Chinese NvShu character images with uneven illumination and low contrast

  6. An adaptation method to improve secret key rates of time-frequency QKD in atmospheric turbulence channels

    Sun, Xiaole; Djordjevic, Ivan B.; Neifeld, Mark A.

    2016-03-01

    Free-space optical (FSO) channels can be characterized by random power fluctuations due to atmospheric turbulence, which is known as scintillation. Weak coherent source based FSO quantum key distribution (QKD) systems suffer from the scintillation effect because during the deep channel fading the expected detection rate drops, which then gives an eavesdropper opportunity to get additional information about protocol by performing photon number splitting (PNS) attack and blocking single-photon pulses without changing QBER. To overcome this problem, in this paper, we study a large-alphabet QKD protocol, which is achieved by using pulse-position modulation (PPM)-like approach that utilizes the time-frequency uncertainty relation of the weak coherent photon state, called here TF-PPM-QKD protocol. We first complete finite size analysis for TF-PPM-QKD protocol to give practical bounds against non-negligible statistical fluctuation due to finite resources in practical implementations. The impact of scintillation under strong atmospheric turbulence regime is studied then. To overcome the secure key rate performance degradation of TF-PPM-QKD caused by scintillation, we propose an adaptation method for compensating the scintillation impact. By changing source intensity according to the channel state information (CSI), obtained by classical channel, the adaptation method improves the performance of QKD system with respect to the secret key rate. The CSI of a time-varying channel can be predicted using stochastic models, such as autoregressive (AR) models. Based on the channel state predictions, we change the source intensity to the optimal value to achieve a higher secret key rate. We demonstrate that the improvement of the adaptation method is dependent on the prediction accuracy.

  7. Improvement of the Hopfield Neural Network by MC-Adaptation Rule

    ZHOU Zhen; ZHAO Hong

    2006-01-01

    We show that the performance of the Hopfield neural networks, especially the quality of the recall and the capacity of the effective storing, can be greatly improved by making use of a recently presented neural network designing method without altering the whole structure of the network. In the improved neural network, a memory pattern is recalled exactly from initial states having a given degree of similarity with the memory pattern, and thus one can avoids to apply the overlap criterion as carried out in the Hopfield neural networks.

  8. Computerized Adaptive Tutorials to Improve and Assess Problem-Solving Skills

    Nirmalakhandan, N.

    2007-01-01

    Recent research studies have reported on how novices and experts differ in storing, organizing, and retrieving subject matter knowledge and on how they apply their knowledge to solve new problems. These findings have been integrated and implemented in a computer environment to help novices improve their problem-solving skills. An outline of this…

  9. Improved prediction error filters for adaptive feedback cancellation in hearing aids

    Ngo, Kim; van Waterschoot, Toon; Christensen, Mads Græsbøll;

    2013-01-01

    a number of improved PEF designs that are inspired by harmonic sinusoidal modeling and pitch prediction of speech signals. The resulting PEM-based AFC algorithms are evaluated in terms of the maximum stable gain (MSG), filter misadjustment, and computational complexity. Simulation results for a...

  10. Glucagon-like peptide 2 treatment may improve intestinal adaptation during weaning

    Thymann, Thomas; Le Huërou-Luron, I; Petersen, Y M;

    2014-01-01

    ) were kept in a low-sanitary environment, leading to weaning diarrhea, and injected with saline or short-acting GLP-2 (200 µg/(kg BW·12 h); n = 11). Treatment with GLP-2 increased goblet cell density (P < 0.05) and reduced short chain fatty acid concentration in the colon (P < 0.01) but had limited......Transition from sow’s milk to solid feed is associated with intestinal atrophy and diarrhea. We hypothesized that the intestinotrophic hormone glucagon-like peptide 2 (GLP-2) would induce a dose- and health status-dependent effect on gut adaptation. In Exp. 1, weaned pigs (average BW at weaning 4...... effects on diarrhea. In Exp. 3, weaned pigs (average BW at weaning 6.90 ± 0.32 kg) were kept in a low-sanitary environment and injected with saline or a long-acting acylated GLP-2 analogue (25 µg/(kg BW·12 h); n = 8). In this experiment, GLP-2 increased intestinal weight (+22%; P < 0.01) and activity of...