Journal articles: 'Signal variation'

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Hu, Wei Bing, Wei Hu, and Yu Zheng. "Wavelet Analysis in Damage Detection for Bridge Structure." Key Engineering Materials 417-418 (October 2009): 813–16. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.813.

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The damage of structure leads to variation of structural modal parameter，so the wavelet transform for damage detection is introduced in this paper for considering the variation. First, structural dynamic response signal on the basis of the vibration-based structural damage diagnosis methods is calculated by structural analysis in the paper, then, each of sub-signals is calculated according to wavelet analysis, also, the sub-signal energy spectrum of dynamic response signal and energy spectrum variation are known. By observing the difference of the sub-signal and the variation of the sub-signal energy spectrum, we can get the variation of structural modal parameter and the sub-signal energy spectrum due to the performance degradation of the whole structure and local variations of damage level and location ,so that this method can be used in on-line damage detection for bridge structure.

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Kämpke, Thomas. "Signal quantization by variation." International Journal of Adaptive Control and Signal Processing 25, no. 12 (July 25, 2011): 1061–73. http://dx.doi.org/10.1002/acs.1264.

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Curry, Claire M., and Michael A. Patten. "Complex spatiotemporal variation in processes shaping song variation." Behaviour 156, no. 10 (2019): 1057–82. http://dx.doi.org/10.1163/1568539x-00003556.

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Abstract Understanding factors that contribute to song divergence bolsters our understanding of signal evolution and reproductive isolation. Hybrid zones often occur across environmental gradients; as such, they are excellent places to examine how signals diverge and how differentiation is maintained. We studied song variation across two hybrid zones, one old and one recent, of Tufted Titmouse (Baeolophus bicolor) and Black-crested Titmouse (B. atricristatus), across an environmental gradient where the two titmouse populations meet. In the recent zone, noise and vegetation structure were correlated with several song characteristics, but in the older zone, these features did not correlate despite similar gradients in song features. Our data, combined with previous studies, suggest that despite overall similarities in characteristics, songs in the older zone may be more shaped by sexual selection, whereas songs in the young zone are shaped by environment. Thus, even within the same species, processes shaping signal structure can vary spatially and temporally.

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Manap, Mustafa, Abdul Rahim Abdullah, Srete Nikolovski, Tole Sutikno, and Mohd Hatta Jopri. "An improved smooth-windowed Wigner-Ville distribution analysis for voltage variation signal." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 5 (October 1, 2020): 4982. http://dx.doi.org/10.11591/ijece.v10i5.pp4982-4991.

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This paper outlines research conducted using bilinear time-frequency distribution (TFD), a smooth-windowed wigner-ville distribution (SWWVD) used to represent time-varying signals in time-frequency representation (TFR). Good time and frequency resolutions offer superiority in SWWVD to analyze voltage variation signals that consist of variations in magnitude. The separable kernel parameters are estimated from the signal in order to get an accurate TFR. The TFR for various kernel parameters is compared by a set of performance measures. The evaluation shows that different kernel settings are required for different signal parameters. Verification of the TFD that operated at optimal kernel parameters is then conducted. SWWVD exhibits a good performance of TFR which gives high peak-to-side lobe ratio (PSLR) and signal-to-cross-terms ratio (SCR) accompanied by low main-lobe width (MLW) and absolute percentage error (APE). This proved that the technique is appropriate for voltage variation signal analysis and it essential for development in an advanced embedded system.

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Chauhan, Bhag C. "7Beneutrino signal variation in KamLAND." Journal of High Energy Physics 2006, no. 02 (February 15, 2006): 035. http://dx.doi.org/10.1088/1126-6708/2006/02/035.

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Derryberry, Elizabeth P. "Male response to historical and geographical variation in bird song." Biology Letters 7, no. 1 (August 4, 2010): 57–59. http://dx.doi.org/10.1098/rsbl.2010.0519.

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In many species, individuals discriminate among sexual signals of conspecific populations in the contexts of mate choice and male–male competition. Differences in signals among populations (geographical variation) are in part the result of signal evolution within populations (temporal variation). Understanding the relative effect of temporal and geographical signal variation on signal salience may therefore provide insight into the evolution of behavioural discrimination. However, no study, to my knowledge, has compared behavioural response to historical signals with response to current signal variation among populations. Here, I measured the response of male white-crowned sparrows ( Zonotrichia leucophrys ) to historical songs compared with current songs from their local population, a nearby non-local population and a distant population. Males responded most strongly to current local songs, less, but equally, to historical local and current non-local songs, and least to songs of the distant population. Moreover, response to both temporal and geographical variation in song was proportional to how much songs differed acoustically from current local songs. Signal evolution on an ecological time scale appears to have an effect on signal salience comparable to differences found between current neighbouring populations, supporting the idea that behavioural discrimination among learned signals of conspecific populations can evolve relatively rapidly.

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Blankers, Thomas, Rik Lievers, Camila Plata, Michiel van Wijk, Dennis van Veldhuizen, and Astrid T. Groot. "Sex pheromone signal and stability covary with fitness." Royal Society Open Science 8, no. 6 (June 2021): 210180. http://dx.doi.org/10.1098/rsos.210180.

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If sexual signals are costly, covariance between signal expression and fitness is expected. Signal–fitness covariance is important, because it can contribute to the maintenance of genetic variation in signals that are under natural or sexual selection. Chemical signals, such as female sex pheromones in moths, have traditionally been assumed to be species-recognition signals, but their relationship with fitness is unclear. Here, we test whether chemical, conspecific mate finding signals covary with fitness in the moth Heliothis subflexa . Additionally, as moth signals are synthesized de novo every night, the maintenance of the signal can be costly. Therefore, we also hypothesized that fitness covaries with signal stability (i.e. lack of temporal intra-individual variation). We measured among- and within-individual variation in pheromone characteristics as well as fecundity, fertility and lifespan in two independent groups that differed in the time in between two pheromone samples. In both groups, we found fitness to be correlated with pheromone amount, composition and stability, supporting both our hypotheses. This study is, to our knowledge, the first to report a correlation between fitness and sex pheromone composition in moths, supporting evidence of condition-dependence and highlighting how signal–fitness covariance may contribute to heritable variation in chemical signals both among and within individuals.

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Carneiro, Mirella, Victor Oliveira, Fernanda Oliveira, Marco Teixeira, and Milena Pinto. "Simulation Analysis of Signal Conditioning Circuits for Plants’ Electrical Signals." Technologies 10, no. 6 (November 25, 2022): 121. http://dx.doi.org/10.3390/technologies10060121.

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Electrical signals are generated and transmitted through plants in response to stimuli caused by external environment factors, such as touching, luminosity, and leaf burning. By analyzing a specific plant’s electrical responses, it is possible to interpret the impact of external aspects in the plasma membrane potential and, thus, determine the cause of the electrical signal. Moreover, these signals permit the whole plant structure to be informed almost instantaneously. This work presents a brief discussion of plants electrophysiology theory and low-cost signal conditioning circuits, which are necessary for the acquisition of plants’ electrical signals. Two signal conditioning circuits, which must be chosen depending on the signal to be measured, are explained in detail and electrical simulation results, performed in OrCAD Capture Software are presented. Furthermore, Monte Carlo simulations were performed to evaluate the impact of components variations on the accuracy and efficiency of the signal conditioning circuits. Those simulations showed that, even after possible component variations, the filters’ cut-off frequencies had at most 4% variation from the mean.

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Iwuji, Prince Chigozie, and Victor Chukwuagozie Onuabuchi. "Investigation of Diurnal Variation of Signal Strength Generated by FM Transmitter." European Scientific Journal, ESJ 14, no. 18 (June 30, 2018): 235. http://dx.doi.org/10.19044/esj.2018.v14n18p235.

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This paper focuses on the determination of the diurnal variation of signal strength generated by Orient 94.4 FM transmitter along six (6) selected route in Imo State, Nigeria. This was carried out with the aid of a constructed signal strength meter (SSM). Signal strength measurements were collected at different time, on different days, and in different months. The measurement was carried out at a constant distance of 20 Km. Arrangement was made with the management of the base station to ensure that the transmitting parameters were kept constant throughout the period of signal strength measurement. The average results of these measurements were taken. The data obtained from the measurements was plotted in a graph to establish the diurnal variation in signal strength along the different routes of signal strength measurement. It was observed from this research that transmission and reception of signals are dependent on the time of the day. High signal strength was noted between the hours of 8 am and 11 am, while low signal strength was recorded between the hours of 1 pm and 5 pm. Better signal strengths were recorded at night. The result of this study shows that signal strength generated by FM transmitter vary with time of the day and the prevalent weather conditions. Stronger signals are recorded mostly at night along the different routes of the study. The signal strength consequently drops in the afternoon and recovers in the morning hours.

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Santhosh, Sheeba. "Bio Impedance Signal Analysis with Variation in Input Signal Frequency." International Journal of Advanced Trends in Computer Science and Engineering 9, no. 4 (August 25, 2020): 5332–36. http://dx.doi.org/10.30534/ijatcse/2020/167942020.

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Chen, Siheng, Aliaksei Sandryhaila, Jose M. F. Moura, and Jelena Kovacevic. "Signal Recovery on Graphs: Variation Minimization." IEEE Transactions on Signal Processing 63, no. 17 (September 2015): 4609–24. http://dx.doi.org/10.1109/tsp.2015.2441042.

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Huang, Hui, Shiyan Hu, and Ye Sun. "A Discrete Curvature Estimation Based Low-Distortion Adaptive Savitzky–Golay Filter for ECG Denoising." Sensors 19, no. 7 (April 4, 2019): 1617. http://dx.doi.org/10.3390/s19071617.

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Electrocardiogram (ECG) sensing is an important application for the diagnosis of cardiovascular diseases. Recently, driven by the emerging technology of wearable electronics, massive wearable ECG sensors are developed, which however brings additional sources of noise contamination on ECG signals from these wearable ECG sensors. In this paper, we propose a new low-distortion adaptive Savitzky-Golay (LDASG) filtering method for ECG denoising based on discrete curvature estimation, which demonstrates better performance than the state of the art of ECG denoising. The standard Savitzky-Golay (SG) filter has a remarkable performance of data smoothing. However, it lacks adaptability to signal variations and thus often induces signal distortion for high-variation signals such as ECG. In our method, the discrete curvature estimation is adapted to represent the signal variation for the purpose of mitigating signal distortion. By adaptively designing the proper SG filter according to the discrete curvature for each data sample, the proposed method still retains the intrinsic advantage of SG filters of excellent data smoothing and further tackles the challenge of denoising high signal variations with low signal distortion. In our experiment, we compared our method with the EMD-wavelet based method and the non-local means (NLM) denoising method in the performance of both noise elimination and signal distortion reduction. Particularly, for the signal distortion reduction, our method decreases in MSE by 33.33% when compared to EMD-wavelet and by 50% when compared to NLM, and decreases in PRD by 18.25% when compared to EMD-wavelet and by 25.24% when compared to NLM. Our method shows high potential and feasibility in wide applications of ECG denoising for both clinical use and consumer electronics.

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Marshall, Heather, and Marisa A. Devine. "Article." Canadian Journal of Chemistry 76, no. 3 (March 1, 1998): 356–58. http://dx.doi.org/10.1139/v98-013.

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The fluorescence signals from replicate samples of uranium taken into fused sodium fluoride beads, read in the prescribed fashion, are not distributed normally. The signal from a single bead shows marked sinusoidal variation as the bead is rotated, and it is the superposition of this sinusoidal variation on the normal variation between beads that gives rise to a widened or even bimodal distribution among replicates. If each bead is read a second time, following a single half rotation, the average of the two readings gives the true signal underlying the sinusoidal variation; the distribution of these true signals represents simply the normal variation between replicate samples, and the precision of results is much improved.Key words: uranium, fluorescence, fluorometry.

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Shin, Sung-Wook, Jung-Hyun Park, Woo-Jin Lee, Sung-Ho Kang, Hyunggun Kim, and Sung-Taek Chung. "Analysis of Electroencephalography Signals on the Contents of Cognitive Function Game: Attention and Memory." Journal of Medical Imaging and Health Informatics 10, no. 6 (June 1, 2020): 1452–58. http://dx.doi.org/10.1166/jmihi.2020.3069.

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In the current study, contents of cognitive function game were developed, and variations in Electroencephalography signals were measured and compared before performing the game tasks and during performing the game. The study sought to assess how much the game contents activated brain to see if they were suitable for cognitive functional training. For Electroencephalography signal analysis, power spectral analysis was implemented to classify signals according to frequency. To test signal variation according to the degree of brain activation before and after performing the game, variation comparison and paired t-test were conducted. Results showed that there was reduction in α wave signaling which implied that the subjects concentrate on the content, and increase in β wave signifying that they were engaged in cognitive activities such as remembering and assessing. Consequentially, the produced contents in this study are expected to be useful for cognitive functional training.

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Lu, Zhichao, Tianbao Zhao, Weican Zhou, and Haikun Zhao. "Interdecadal Variation of the Antarctic Circumpolar Wave Based on the 20CRV3 Dataset." Atmosphere 13, no. 5 (May 4, 2022): 736. http://dx.doi.org/10.3390/atmos13050736.

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As a large-scale ocean–atmosphere coupling system in the Southern Hemisphere, the Antarctic Circumpolar Wave (ACW) greatly impacts the global climate. However, the interdecadal variation of the ACW has rarely been studied due to the lack of long-term data. In this research, the latest 20th Century Reanalysis Version 3 dataset is used to analyze the interdecadal variations of sea level pressure (SLP) and sea surface temperature (SST) signals in the ACW during 1836–2015. The results indicate that the ACW has not always been present in the recent 180 years, and it has remarkable interdecadal variations. Specifically, the ACW was hard to distinguish before the 1870s. The SLP anomalies propagated eastwards over the South Pacific and South Atlantic during part of the 1880s–1940s. The SST anomalies also have an eastward propagation in the 1880s–1960s. The most active period of the SLP signal is in the 1950s–1990s, while that of the SST signal is in the 1980s–1990s. The ACW has not been significant since the 21st century. The interdecadal variation of the SLP may be related to the variations of the long-term Southern Annular Mode and Pacific-South American pattern, while the interdecadal variation of the SST is more associated with the ENSO.

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Hari Krishnan G, Hari Krishnan G., Dr Ananda Natarajan R, and Dr Anima Nanda. "Input Signal Voltage Variation and its Effects on Non Invasive Bio-impedance Diagnosis." Indian Journal of Applied Research 4, no. 2 (October 1, 2011): 13–14. http://dx.doi.org/10.15373/2249555x/feb2014/58.

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Ye, Jia. "How Variation in Signal Quality Affects Performance." Financial Analysts Journal 64, no. 4 (July 2008): 48–61. http://dx.doi.org/10.2469/faj.v64.n4.5.

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Lander, Eric S. "Signal transduction, cancer classification and genetic variation." Nature Genetics 23, S3 (November 1999): 29. http://dx.doi.org/10.1038/14256.

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Čokl, Andrej, Alenka Žunič, and Jocelyn Millar. "Transmission of Podisus maculiventris tremulatory signals through plants." Open Life Sciences 4, no. 4 (December 1, 2009): 585–94. http://dx.doi.org/10.2478/s11535-009-0043-z.

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AbstractMales of the predaceous stink bug Podisus maculiventris (Say) (Heteroptera: Pentatomidae: Asopinae) emit low frequency tremulatory signals. Laser vibrometry was used to record and analyze naturally emitted signals, focusing on variation in signal velocity and frequency during transmission through plants (Phaseolus vulgaris L. and Plumbago auriculata Lam.) as a function of distance from the vibrational source. Signal velocity varied individually between 2 and 15 mm/s recorded on a plant close to the calling male and decreased by 0.3 to 1.5 dB/cm on bean and 0.3 to 0.9 dB/cm on plumbago. The dominant frequency of signals was variable at frequencies below 50 Hz. On bean frequencies centered around 10 Hz or 20 Hz were dominant for signals recorded at the source. Transmission through bean resulted in an increase in the 20 Hz peak relative to other frequencies in the signal. Variation of the dominant frequencies of signals transmitted through plumbago stems were more predictable, showing typical changes in amplitude relative to the distance from the source. The regular variation of the dominant frequency along the stem with linear increase of signal velocity at decreasing distance from the source may provide plant-dwelling insects with information about the distance to the calling individual.

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Lee, Jia-Hua, Tzu-Chien Hsiao, Chia-Chi Chang, and Hung-Yi Hsu. "Magnitude Variation of Arterial Blood Pressure Measured Using Holo–Hilbert Spectral Analysis." Advances in Data Science and Adaptive Analysis 10, no. 03 (July 2018): 1850007. http://dx.doi.org/10.1142/s2424922x18500079.

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Arterial blood pressure (ABP) is one of the most crucial cardiovascular indicators in clinical practice. Hilbert–Huang transform (HHT) has been performed on ABP signals and resulted in ABP variability. The instantaneous P-wave interval variation had been further examined with baroreflex sensitivity. However, the instantaneous magnitude variation of ABP signal is still unclear with the pulse pressure (PP) variability. In 2016, Holo–Hilbert spectral analysis (HHSA) extended the HHT method for identifying the amplitude-modulated (AM) characteristics of signals. This method was applied to investigate the magnitude variation of ABP signal during different respiratory manipulations in this study. The results indicated that the AM parts were moderately correlated with PP series and corresponding respiratory patterns. The [Formula: see text]-values on PP series are [Formula: see text], and [Formula: see text] for spontaneous breathing, six-cycle breathing, and hyperventilation, respectively. The values on respiratory patterns are [Formula: see text], and [Formula: see text] for spontaneous breathing, six-cycle breathing, and hyperventilation, respectively. This study concludes that ABP signal with HHSA presents the corresponding PP series, the respiratory-related activities, and the respiratory effect on PP variability. This is the first demonstration of the magnitude variation of ABP signal and further research in this area is warranted.

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Zhou, Maosheng, Xin Liu, Jiajia Yuan, Xin Jin, Yupeng Niu, Jinyun Guo, and Hao Gao. "Seasonal Variation of GPS-Derived the Principal Ocean Tidal Constituents’ Loading Displacement Parameters Based on Moving Harmonic Analysis in Hong Kong." Remote Sensing 13, no. 2 (January 14, 2021): 279. http://dx.doi.org/10.3390/rs13020279.

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The classical harmonic analysis (CHA) method only can be used to obtain the harmonic constants (amplitude and phase) of ocean tide loading displacement (OTLD). In fact, there are significant seasonal variations in the harmonic constants of OTLD. A moving harmonic analysis (MHA) method is proposed, which can effectively capture the seasonal variation of OTLD parameters. Based on 5 years of kinematic coordinate time series in direction U of six Global Positioning System (GPS) stations in Hong Kong, the MHA method is used to explore the seasonal variation of the OTLD parameters of the 6 principal tidal constituents (M2, S2, N2, K1, O1, Q1). The influence of mass loading on the seasonal variation of OTLD parameters is analyzed. The results show that there are obviously seasonal variations in OTLD parameters of the 6 principal tidal constituents in Hong Kong. The OTLD’s amplitude’s changes of the 6 principal tidal constituents are around 4–25.1% and the oscillation ranges of OTLD’s phase parameters vary from 8.8° to 20.4°. Among the seasonal variations of OTLD parameters, the annual signal, the semi-annual signal, and the ter-annual signal are the most significant. By analyzing the influence of atmospheric loading on the seasonal variation of OTLD parameters, it is found that atmospheric loading has certain contribution to the seasonal variation of OTLD parameters. Hydrological loading and non-tidal ocean loading have little influence on the seasonal variation of OTLD parameters.

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Kechik, D. A., Yu P. Aslamov, and I. G. Davydov. "Method of estimation of frequency variation relying on estimation of shift of spectral peaks." «System analysis and applied information science», no. 1 (April 26, 2021): 53–61. http://dx.doi.org/10.21122/2309-4923-2021-1-53-61.

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Problem of estimation of variated frequency of components of polyharmonic signals has been arose. Three-dimensional time-frequency representation of signals is usually used to resolve this problem. But simple and reliable method of instantaneous frequency tracking is needed. Frequency tracking method based on estimation of shifts of peaks of spectrogram has been proposed in this paper. It is assumed that shift of spectral peaks of components of signal is proportional to variation of fundamental frequency. Logarithmic scaling of time-frequency representation is used to make spectral peaks equidistant. Temporal dependence of shift of spectral maximums is obtained using correlation of windowed spectrum at the first frame and spectrum of signal in the current window. Then obtained track is translated in linear scale. Proposed method does not estimate values of instantaneous frequency or central frequency of signal component but estimates its variation. Advantage of the method is that it can estimate frequency track even if range of frequency variation and its central value are known roughly or unknown at all. Multiple components do not interfere to estimate fundamental frequency variation. Reduction of bandwidth is recommended to increase accuracy of frequency track estimation, but analysis of time-frequency representation containing a few components is also possible. Dependency of performance of analysis of synthetic signals using the method on various signal to noise ratios under different conditions was estimated. Applicability of the method for vibrational diagnosing of rotary equipment was checked out using spectral interference method.

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Stanković, Ljubiša, and Miloš Daković. "On the Uniqueness of the Sparse Signals Reconstruction Based on the Missing Samples Variation Analysis." Mathematical Problems in Engineering 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/629759.

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An approach to sparse signals reconstruction considering its missing measurements/samples as variables is recently proposed. Number and positions of missing samples determine the uniqueness of the solution. It has been assumed that analyzed signals are sparse in the discrete Fourier transform (DFT) domain. A theorem for simple uniqueness check is proposed. Two forms of the theorem are presented, for an arbitrary sparse signal and for an already reconstructed signal. The results are demonstrated on illustrative and statistical examples.

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Rainer, M., F. Borsa, L. Pino, G. Frustagli, M. Brogi, K. Biazzo, A. S. Bonomo, et al. "The GAPS programme at TNG." Astronomy & Astrophysics 649 (May 2021): A29. http://dx.doi.org/10.1051/0004-6361/202039247.

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Context. Transiting ultra-hot Jupiters are ideal candidates for studying the exoplanet atmospheres and their dynamics, particularly by means of high-resolution spectra with high signal-to-noise ratios. One such object is KELT-20b. It orbits the fast-rotating A2-type star KELT-20. Many atomic species have been found in its atmosphere, with blueshifted signals that indicate a day- to night-side wind. Aims. We observe the atmospheric Rossiter-McLaughlin effect in the ultra-hot Jupiter KELT-20b and study any variation of the atmospheric signal during the transit. For this purpose, we analysed five nights of HARPS-N spectra covering five transits of KELT-20b. Methods. We computed the mean line profiles of the spectra with a least-squares deconvolution using a stellar mask obtained from the Vienna Atomic Line Database (Teff = 10 000 K, log g = 4.3), and then we extracted the stellar radial velocities by fitting them with a rotational broadening profile in order to obtain the radial velocity time-series. We used the mean line profile residuals tomography to analyse the planetary atmospheric signal and its variations. We also used the cross-correlation method to study a previously reported double-peak feature in the FeI planetary signal. Results. We observed both the classical and the atmospheric Rossiter-McLaughlin effect in the radial velocity time-series. The latter gave us an estimate of the radius of the planetary atmosphere that correlates with the stellar mask used in our work (Rp+atmo∕Rp = 1.13 ± 0.02). We isolated the planetary atmospheric trace in the tomography, and we found radial velocity variations of the planetary atmospheric signal during transit with an overall blueshift of ≈10 km s−1, along with small variations in the signal depth, and less significant, in the full width at half maximum (FWHM). We also find a possible variation in the structure and position of the FeI signal in different transits. Conclusions. We confirm the previously detected blueshift of the atmospheric signal during the transit. The FWHM variations of the atmospheric signal, if confirmed, may be caused by more turbulent condition at the beginning of the transit, by a variable contribution of the elements present in the stellar mask to the overall planetary atmospheric signal, or by iron condensation. The FeI signal show indications of variability from one transit to the next.

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Afgan, Muhammad Sher, Sahar Sheta, Yuzhou Song, Weilun Gu, and Zhe Wang. "Plasma imaging for physical variations in laser-induced aerosol plasma with particle size increase." Journal of Analytical Atomic Spectrometry 35, no. 11 (2020): 2649–55. http://dx.doi.org/10.1039/d0ja00297f.

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Süle, Ihsan. "Characterization of twist of fancy yarns using wavelet analysis of sensor signal." Textile Research Journal 90, no. 23-24 (May 13, 2020): 2592–612. http://dx.doi.org/10.1177/0040517520925496.

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Yarn twist variations may cause stripes in the direction of weft yarns or local defects on a fabric surface. Since fast Fourier transform and time analysis cannot directly detect local frequency variations of yarn signal and defect sensors are designed to detect the diameter decreases without considering frequency analysis, no data associated with twist-related frequency changes can be obtained when inspecting Chenille yarn (Cy) defects. This study proposes the prediction of twist level ( T) and twist variations ( ΔT) of Cy whose twist changes in accordance with the spatial period of pile density by using wavelet analysis, allowing localized frequency variations to be obtained. Complex-valued Paul wavelet was used to determine the ΔT of signals with small frequency fluctuations, while Morlet wavelet was addressed for signals with high frequency change. The relation of the signal frequency to the pile yarn density and, correspondingly, twist was modeled by equations. To prevent discontinuities in wavelet cross-spectrum (WCS), the twist simulation signal was generated by equalizing twist oscillation amplitudes without changing their phase. To compare ideal twist to the local twist, another simulation signal demonstrating the ideal twist at sample-specific frequency was generated. The WCS of the simulation signals allowing the segmentation of variation intervals was used for determining ΔT and yarn portions, where the twist is compatible with ideal twist, by establishing correlation between scales and twists. For yarn samples with various T and ΔT types, the T and ΔT results obtained by the proposed wavelet-based algorithm showed the mean absolute relative percentage errors of 1.617% and 37.062%, respectively.

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Sahota, Komal. "Digital Transmission in Computer Network." Journal of Analog and Digital Communications 7, no. 2 (August 23, 2022): 8–12. http://dx.doi.org/10.46610/joadc.2022.v07i02.002.

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A type of signal transmission known as "digital transmission" involves the discrete time variation of two values, one of which represents the binary number "0" and the other "1." Voltage or electrical potential is often the variable amount in copper cabling. Fiber-optic wiring or wireless communication use variations in intensity or any other physical quantity. Digital signals use discrete values to transmit binary data through a communication path like a network cable or a telecommunications link. On a serial transmission line, a digital signal is transmitted one bit at a time. Analog and digital methods can both be used to store data or information. On a serial transmission line, a digital signal is transmitted one bit at a time. Analog and digital methods can both be used to store data or information.

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Winters, Anne E., Naomi F. Green, Nerida G. Wilson, Martin J. How, Mary J. Garson, N. Justin Marshall, and Karen L. Cheney. "Stabilizing selection on individual pattern elements of aposematic signals." Proceedings of the Royal Society B: Biological Sciences 284, no. 1861 (August 23, 2017): 20170926. http://dx.doi.org/10.1098/rspb.2017.0926.

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Warning signal variation is ubiquitous but paradoxical: low variability should aid recognition and learning by predators. However, spatial variability in the direction and strength of selection for individual elements of the warning signal may allow phenotypic variation for some components, but not others. Variation in selection may occur if predators only learn particular colour pattern components rather than the entire signal. Here, we used a nudibranch mollusc, Goniobranchus splendidus , which exhibits a conspicuous red spot/white body/yellow rim colour pattern, to test this hypothesis. We first demonstrated that secondary metabolites stored within the nudibranch were unpalatable to a marine organism. Using pattern analysis, we demonstrated that the yellow rim remained invariable within and between populations; however, red spots varied significantly in both colour and pattern. In behavioural experiments, a potential fish predator, Rhinecanthus aculeatus , used the presence of the yellow rims to recognize and avoid warning signals. Yellow rims remained stable in the presence of high genetic divergence among populations. We therefore suggest that how predators learn warning signals may cause stabilizing selection on individual colour pattern elements, and will thus have important implications on the evolution of warning signals.

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Rojas, Bibiana, Jennifer Devillechabrolle, and John A. Endler. "Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs." Biology Letters 10, no. 6 (June 2014): 20140193. http://dx.doi.org/10.1098/rsbl.2014.0193.

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Aposematic signal variation is a paradox: predators are better at learning and retaining the association between conspicuousness and unprofitability when signal variation is low. Movement patterns and variable colour patterns are linked in non-aposematic species: striped patterns generate illusions of altered speed and direction when moving linearly, affecting predators' tracking ability; blotched patterns benefit instead from unpredictable pauses and random movement. We tested whether the extensive colour-pattern variation in an aposematic frog is linked to movement, and found that individuals moving directionally and faster have more elongated patterns than individuals moving randomly and slowly. This may help explain the paradox of polymorphic aposematism: variable warning signals may reduce protection, but predator defence might still be effective if specific behaviours are tuned to specific signals. The interacting effects of behavioural and morphological traits may be a key to the evolution of warning signals.

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Xie, Binbin, Yuqing Yin, and Jie Xiong. "Pushing the Limits of Long Range Wireless Sensing with LoRa." Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 5, no. 3 (September 9, 2021): 1–21. http://dx.doi.org/10.1145/3478080.

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Wireless sensing is an exciting new research area which enables a large variety of applications ranging from coarse-grained daily activity recognition to fine-grained vital sign monitoring. While promising in many aspects, one critical issue is the limited sensing range because weak reflection signals are used for sensing. Recently, LoRa signals are exploited for wireless sensing, moving a big step towards long-range sensing. Although promising, there is still a huge room for improvement. In this work, we qualitatively characterize the relationship between target movements and target-induced signal variations, and propose signal processing methods to enlarge the induced signal variation to achieve a longer sensing range. Experiment results show that the proposed system (1) pushes the contact-free sensing range of human walking from the state-of-the-art 50 m to 120 m; (2) achieves a sensing range of 75 m for fine-grained respiration sensing; and (3) demonstrates human respiration sensing even through seven concrete walls.

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Nie, Chun Yan, Rui Li, and Ju Wang. "Emotion Recognition Based on Chaos Characteristics of Physiological Signals." Applied Mechanics and Materials 380-384 (August 2013): 3750–53. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.3750.

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Changes of physiological signals are affected by human emotions, but also the emotional fluctuations are reflected by the body's variation of physiological signal's feature. Physiological signal is a non-linear signal ,nonlinear dynamics and biomedical engineering ,which based on chaos theory, providing us a new method for studying on the parameters of these complex physiological signals which can hardly described by the classical theory. This paper shows physiological emotion signal recognition system based on the chaotic characteristics, and than describes some current applications of chaotic characteristics for multiple physiological signals on emotional recognition.

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Damulira, Edrine, Muhammad Nur Salihin Yusoff, Ahmad Fairuz Omar, and Nur Hartini Mohd Taib. "Amplification of Radiation-Induced Signal of LED Strip by Increasing Number of LED Chips and Using Amplifier Board." Applied Sciences 10, no. 2 (January 16, 2020): 651. http://dx.doi.org/10.3390/app10020651.

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Transducers, such as photodiodes, phototransistors, and photovoltaic cells are promising radiation detectors. However, for accurate radiation detection and dosimetry, signals that emanate from these devices have to be sufficient to facilitate accurate calibrations, i.e., assigning a quantity of radiation dose to a specific magnitude of the signal. More so, purposely fabricated for luminescence, LEDs produce significantly low signals during radiation detection applications. Therefore, this paper investigates the enhancement and augmentation of photovoltaic signals that were generated when LED strips were being exposed to diagnostic X-rays. Initially, signal amplification was achieved through increasing the effective LED active area (from 60 to 120 chips); by successively connecting LED strips. Further, signal amplification was undertaken by injecting the raw LED strip signal into an amplifier board with adjustable gains. In both the signal amplification techniques, the tube voltage (kVp), tube current-time product (mAs), and source-to-detector distance (SDD) were varied. The principal findings show that effective active area-based signal amplifications produced an overall average of 91.16% signal enhancement throughout all of the X-ray parameter variations. On the other hand, the amplifier board produced an average of 36.48% signal enhancement for the signals that were injected into it. Chip number increment-based signal amplifications had a 0.687% less coefficient of variation than amplifier board signal amplifications. The amplifier board signal amplifications were impaired by factors, such as dark currents, amplifier board maximum operational output voltage, and saturation. Therefore, future electronic signal amplification could use amplifier boards having low dark currents and high operational voltage headroom. The low-cost and simplicity that are associated with active-area amplification could be further exploited in a hybrid amplification technique with electronic amplification and scintillators.

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B. Oluwafemi, I., and O. J. Femi-Jemilohun. "Propagation Profile and Signal Strength Variation of VHF Signal in Ekiti State Nigeria." International Journal of Wireless and Microwave Technologies 7, no. 3 (May 8, 2017): 9–24. http://dx.doi.org/10.5815/ijwmt.2017.03.02.

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White, Brittney A., Sofia R. Prado-Irwin, and Levi N. Gray. "FEMALE SIGNAL VARIATION IN THE ANOLIS LEMURINUS GROUP." Breviora 564, no. 1 (July 3, 2019): 1. http://dx.doi.org/10.3099/0006-9698-564.1.1.

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Helhel, Selçuk, Şükrü Özen, and Hüseyin Göksu. "INVESTIGATION OF GSM SIGNAL VARIATION DEPENDING WEATHER CONDITIONS." Progress In Electromagnetics Research B 1 (2008): 147–57. http://dx.doi.org/10.2528/pierb07101503.

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Chao Yang and A. Mason. "Process/Temperature Variation Tolerant Precision Signal Strength Indicator." IEEE Transactions on Circuits and Systems I: Regular Papers 55, no. 3 (April 2008): 722–29. http://dx.doi.org/10.1109/tcsi.2008.919747.

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Lipschutz, Brigitte, John Ashburner, Karl Friston, and Cathy Price. "Assessing study-specific regional variation in fMRI signal." NeuroImage 11, no. 5 (May 2000): S460. http://dx.doi.org/10.1016/s1053-8119(00)91391-0.

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Garreffa, G. "BOLD signal sign and transient vessels volume variation." Magnetic Resonance Imaging 21, no. 10 (December 2003): 1207–12. http://dx.doi.org/10.1016/j.mri.2003.08.022.

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Digman, Matthew C., and Neil J. Cornish. "LISA Gravitational Wave Sources in a Time-varying Galactic Stochastic Background." Astrophysical Journal 940, no. 1 (November 1, 2022): 10. http://dx.doi.org/10.3847/1538-4357/ac9139.

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Abstract A unique challenge for data analysis with the Laser Interferometer Space Antenna (LISA) is that the noise backgrounds from instrumental noise and astrophysical sources will change significantly over both the year and the entire mission. Variations in the noise levels will be on timescales comparable to, or shorter than, the time most signals spend in the detector’s sensitive band. The variation in the amplitude of the galactic stochastic GW background from galactic binaries as the antenna pattern rotates relative to the galactic center is a particularly significant component of the noise variation. LISA’s sensitivity to different source classes will therefore vary as a function of sky location and time. The variation will impact both overall signal-to-noise and the efficiency of alerts to EM observers to search for multimessenger counterparts.

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Gong, Tao, Jianhua Yang, Miguel A. F. Sanjuán, Houguang Liu, and Zhen Shan. "Vibrational resonance by using a real-time scale transformation method." Physica Scripta 97, no. 4 (March 17, 2022): 045207. http://dx.doi.org/10.1088/1402-4896/ac5bc5.

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Abstract Vibrational resonance (VR) shows great advantages in signal enhancement. Nonlinear frequency modulated (NLFM) signals widely exist in various fields, so it is of great significance to enhance a NLFM signal. However, for the complex NLFM signal, where its instantaneous frequency of the signal varies nonlinearly, the traditional VR method is no longer applicable. To solve this problem, a rescaled VR method by a real-time scale transformation method is proposed. Its basic principle is to use the real-time scale coefficient and auxiliary signal parameters to match a NLFM signal in a nonlinear system. The corresponding numerical simulation is carried out to process three kinds of typical NLFM signals. The results manifest the excellent performance of the proposed method for the signal enhancement of NLFM signals. The method can process NLFM signals with an arbitrary frequency variation. Consequently, it has certain theoretical and practical values in some fields.

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Tee, Weihown, M. R. Yusoff, M. Faizal Yaakub, and A. R. Abdullah. "Voltage variations identification using gabor transform and rule-based classification method." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 1 (February 1, 2020): 681. http://dx.doi.org/10.11591/ijece.v10i1.pp681-689.

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This paper presents a comparatively contemporary easy to use technique for the identification and classification of voltage variations. The technique was established based on the Gabor Transform and the rule-based classification method. The technique was tested by using mathematical model of Power Quality (PQ) disturbances based on the IEEE Std 519-2009. The PQ disturbances focused were the voltage variations, which included voltage sag, swell and interruption. A total of 80 signals were simulated from the mathematical model in MATLAB and used in this study. The signals were analyzed by using Gabor Transform and the signal pattern, time-frequency representation (TFR) and root-mean-square voltage graph were presented in this paper. The features of the analysis were extracted, and rules were implemented in rule-based classification to identify and classify the voltage variation accordingly. The results showed that this method is easy to be used and has good accuracy in classifying the voltage variation.

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He, Wentao, Cancan Yi, Yourong Li, and Han Xiao. "Research on Mechanical Fault Diagnosis Scheme Based on Improved Wavelet Total Variation Denoising." Shock and Vibration 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/3151802.

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Wavelet analysis is a powerful tool for signal processing and mechanical equipment fault diagnosis due to the advantages of multiresolution analysis and excellent local characteristics in time-frequency domain. Wavelet total variation (WATV) was recently developed based on the traditional wavelet analysis method, which combines the advantages of wavelet-domain sparsity and total variation (TV) regularization. In order to guarantee the sparsity and the convexity of the total objective function, nonconvex penalty function is chosen as a new wavelet penalty function in WATV. The actual noise reduction effect of WATV method largely depends on the estimation of the noise signal variance. In this paper, an improved wavelet total variation (IWATV) denoising method was introduced. The local variance analysis on wavelet coefficients obtained from the wavelet decomposition of noisy signals is employed to estimate the noise variance so as to provide a scientific evaluation index. Through the analysis of the numerical simulation signal and real-word failure data, the results demonstrated that the IWATV method has obvious advantages over the traditional wavelet threshold denoising and total variation denoising method in the mechanical fault diagnose.

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Wang, Bao Jie, Yan Men, and Gang Zheng. "A Frequency Tracking Adaptive Power Line Interference Canceller for Electrocardiogram." Applied Mechanics and Materials 556-562 (May 2014): 1506–9. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.1506.

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Power line interference (PLI) may lead to the signal-to-noise ratio (SNR) decline sharply on biomedical signals, including the electrocardiogram (ECG). The proposed method employs the relationship of frequency and weights in adaptive filter to track the frequency variation of PLI. Real ECG signals from MIT-BIH database was used in the experiment, and they were corrupt by an artificial PLI signal for experiment. Correction performances of the proposed method and traditional adaptive method were compared by SNR in the paper. The results showed that the proposed method is consistently superior to the traditional one when the power line interference is vary with time, and the proposed method can track the variation of power line interference effectively.

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Yan, Tao, Zuping Tang, Jiaolong Wei, Bo Qu, and Zhihui Zhou. "A Quasi-constant Envelope Multiplexing Technique for GNSS Signals." Journal of Navigation 68, no. 4 (March 5, 2015): 791–808. http://dx.doi.org/10.1017/s0373463315000119.

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A significant feature of the modernised Global Navigation Satellite System (GNSS) signals is that there are multiple signal components needing to be transmitted on a carrier frequency. How to combine these signal components into a constant envelope composite signal is a challenge. Existing constant envelope modulation techniques have some limitations, and are not effective enough. To solve this problem, we propose a quasi-constant-envelope multiplexing technique in this paper. The proposed method is based on numerical optimisation, and can work in two ways. The corresponding objective functions are provided. To verify the performance of the proposed method, we present three application examples. Results show that the first variation of our method can reach the same combining performance as Phase-Optimised Constant-Envelope Transmission (POCET). In the second variation, the combining efficiency can be pre-set. We can reach higher combining efficiency than POCET, and the envelope of the composite signal becomes quasi-constant. Furthermore, the inter-modulation signals in the final composite signal are adjustable. With the help of the proposed method, we can learn more details of the combining scheme than with POCET.

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Gao, Ruiyang, Wenwei Li, Yaxiong Xie, Enze Yi, Leye Wang, Dan Wu, and Daqing Zhang. "Towards Robust Gesture Recognition by Characterizing the Sensing Quality of WiFi Signals." Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 6, no. 1 (March 29, 2022): 1–26. http://dx.doi.org/10.1145/3517241.

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WiFi-based gesture recognition emerges in recent years and attracts extensive attention from researchers. Recognizing gestures via WiFi signal is feasible because a human gesture introduces a time series of variations to the received raw signal. The major challenge for building a ubiquitous gesture recognition system is that the mapping between each gesture and the series of signal variations is not unique, exact the same gesture but performed at different locations or with different orientations towards the transceivers generates entirely different gesture signals (variations). To remove the location dependency, prior work proposes to use gesture-level location-independent features to characterize the gesture instead of directly matching the signal variation pattern. We observe that gesture-level features cannot fully remove the location dependency since the signal qualities inside each gesture are different and also depends on the location. Therefore, we divide the signal time series of each gesture into segments according to their qualities and propose customized signal processing techniques to handle them separately. To realize this goal, we characterize signal's sensing quality by building a mathematical model that links the gesture signal with the ambient noise, from which we further derive a unique metric i.e., error of dynamic phase index (EDP-index) to quantitatively describe the sensing quality of signal segments of each gesture. We then propose a quality-oriented signal processing framework that maximizes the contribution of the high-quality signal segments and minimizes the impact of low-quality signal segments to improve the performance of gesture recognition applications. We develop a prototype on COTS WiFi devices. The extensive experimental results demonstrate that our system can recognize gestures with an accuracy of more than 94% on average, and significant improvements compared with state-of-arts.

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Chang, Kang-Ming, Peng-Ta Liu, and Ta-Sen Wei. "Electromyography Parameter Variations with Electrocardiography Noise." Sensors 22, no. 16 (August 9, 2022): 5948. http://dx.doi.org/10.3390/s22165948.

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Electromyograms (EMG signals) may be contaminated by electrocardiographic (ECG) signals that cannot be easily separated with traditional filters, because both signals have some overlapping spectral components. Therefore, the first challenge encountered in signal processing is to extract the ECG noise from the EMG signal. In this study, the EMG, mixed with different degrees of noise (ECG), is simulated to investigate the variations of the EMG features. Simulated data were derived from the MIT-BIH Noise Stress Test (NSTD) Database. Two EMG and four ECG data were composed with four EMG/ECG SNR to 32 simulated signals. Following Pan-Tompkins R-peak detection, four ECG removal methods were used to remove ECG with different compensation algorithms to obtain the denoised EMG signal. A total of 13 time-domain and four frequency-domain EMG features were calculated from the denoised EMG. In addition, the similarity of denoised EMG features compared to clean EMG was also evaluated. Our results showed that with the ratio EMG/ECG SNR = 10 and 20, the ECG can be almost ignored, and the similarity of EMG features is close to 1. When EMG/ECG SNR = 1 and 2, there is a large variation of EMG features. The results of our simulation study would be beneficial for understanding the variations of EMG features upon the different EMG/ECG SNR.

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Liou, Ren Jean. "Ultrasonic Signal Reconstruction Using Compressed Sensing." Applied Mechanics and Materials 855 (October 2016): 165–70. http://dx.doi.org/10.4028/www.scientific.net/amm.855.165.

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Ultrasonic signal reconstruction for Structural Health Monitoring is a topic that has been discussed extensively. In this paper, we will apply the techniques of compressed sensing to reconstruct ultrasonic signals that are seriously damaged. To reconstruct the data, the application of conventional interpolation techniques is restricted under the criteria of Nyquist sampling theorem. The newly developed technique - compressed sensing breaks the limitations of Nyquist rate and provides effective results based upon sparse signal reconstruction. Sparse representation is constructed using Fourier transform basis. An l1-norm optimization is then applied for reconstruction. Signals with temperature characteristics were synthetically created. We seriously corrupted these signals and tested the efficacy of our approach under two different scenarios. Firstly, the signal is randomly sampled at very low rates. Secondly, selected intervals were completely blank out. Simulation results show that the signals are effectively reconstructed. It outperforms conventional Spline interpolation in signal-to-noise ratio (SNR) with low variation, especially under very low data rates. This research demonstrates very promising results of using compressed sensing for ultrasonic signal reconstruction.

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Wu, Junpeng, Jian Cai, Jiyuan Yang, Jian Zhang, and Zhiquan Zhou. "A High Reliability Damage Imaging Method Under Environmental Temperature Variations." Journal of Physics: Conference Series 2184, no. 1 (March 1, 2022): 012036. http://dx.doi.org/10.1088/1742-6596/2184/1/012036.

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Abstract In Lamb wave-based structural health monitoring (SHM), the environmental temperature variations can easily affect Lamb wave monitoring signals and seriously reduce the reliability of final damage detection results. To resolve the temperature effect problem, a temperature compensation method of improved baseline signal stretch (IBSS) is presented and applied for high reliability damage imaging under large environmental temperature variations in this paper. After the basic principle of IBSS is analyzed, the realization of IBSS is discussed. Then, a IBSS-based high reliability damage imaging method under temperature variation situation is developed. An experimental study is finally arranged.

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Giery, Sean T., and Craig A. Layman. "Interpopulation Variation in a Condition-Dependent Signal: Predation Regime Affects Signal Intensity and Reliability." American Naturalist 186, no. 2 (August 2015): 187–95. http://dx.doi.org/10.1086/682068.

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Aksenova, Tetiana, and Tatyana V. Ryzhkova. "Oscillatory Models for Biological Signal Processing and Pattern Recognition." EPJ Web of Conferences 224 (2019): 03004. http://dx.doi.org/10.1051/epjconf/201922403004.

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Among biomedical signals, repetitive or quasi-periodic signals are particularly widespread. While the periodic component is still presented these signals are characterized by period variations (fundamental frequency, amplitude, etc.). The lack of synchronization or phase shifts results in variations in similar segments’ durations, nominally identical signals demonstrate a variation at peak retention times, etc. The inverse methods of oscillation theory were proposed recently as a tool to solve the problems of modelling of repetitive signals with phase shift. In the article, the inverse method of oscillation theory is considered as a tool to solve the problems of supervised and non-supervised classification, and filtering of repetitive signals with phase shift. Examples of application are presented.

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Journal articles on the topic 'Signal variation'

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