Literatura académica sobre el tema "Maximal frequency selection"
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Artículos de revistas sobre el tema "Maximal frequency selection"
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Soriano, Jonathan y Sarah Marzen. "How Well Can We Infer Selection Benefits and Mutation Rates from Allele Frequencies?" Entropy 25, n.º 4 (4 de abril de 2023): 615. http://dx.doi.org/10.3390/e25040615.
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Experimentalists observe allele frequency distributions and try to infer mutation rates and selection coefficients. How easy is this? We calculate limits to their ability in the context of the Wright-Fisher model by first finding the maximal amount of information that can be acquired using allele frequencies about the mutation rate and selection coefficient– at least 2 bits per allele– and then by finding how the organisms would have shaped their mutation rates and selection coefficients so as to maximize the information transfer.
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Ma, Debiao, Junteng Zheng y Lizhi Peng. "Performance Evaluation of Epileptic Seizure Prediction Using Time, Frequency, and Time–Frequency Domain Measures". Processes 9, n.º 4 (13 de abril de 2021): 682. http://dx.doi.org/10.3390/pr9040682.
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The prediction of epileptic seizures is crucial to aid patients in gaining early warning and taking effective intervention. Several features have been explored to predict the onset via electroencephalography signals, which are typically non-stationary, dynamic, and varying from person-to-person. In the former literature, features applied in the classification have shared similar contributions to all patients. Therefore, in this paper, we analyze the impact of the specific combination of feature and channel from time, frequency, and time–frequency domains on prediction performance of disparate patients. Based on the minimal-redundancy-maximal-relevance criterion, the proposed framework uses a sequential forward selection approach to individually find the optimal features and channels. Trained models could discriminate the pre-ictal and inter-ictal electroencephalography with a sensitivity of 90.2% and a false prediction rate of 0.096/h. We also present the comparison between the classification accuracy obtained by the optimal features, several features summarized from optimal features, and the complete set of features from three domains. The results indicate that various patient interpretations have a certain specificity in the selection of feature-channel. Furthermore, the detailed list of optimal features and summarized features are proffered for reference to those who research the corresponding database.
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Luhanga, Matthew L. "Packet Error Probability for Diversity Systems in Slow Rayleigh Fading and Gaussian Noise". International Journal of Electrical Engineering & Education 23, n.º 3 (julio de 1986): 239–44. http://dx.doi.org/10.1177/002072098602300309.
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Analytical results on packet error probability for noncoherent frequency-shift-keying (NCFSK) and differential phase-shift-keying (DPSK) systems with diversity reception operating over slow Rayleigh fading channels with Gaussian noise are derived. Expressions obtained are applicable to two linear combining schemes: selection combining and maximal-ratio combining.
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Kuroha, Akihiro, Chang-Jun Ahn, Tatsuya Omori y Ken-ya Hashimoto. "Multiuser Diversity OFDMA using Power Priority Selection and Adaptive Clipping". International Journal of Distributed Systems and Technologies 5, n.º 4 (octubre de 2014): 18–30. http://dx.doi.org/10.4018/ijdst.2014100102.
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In recent, orthogonal frequency division multiple access (OFDMA) has been used for a multiuser wireless communication. In a wireless network, the transmitted signal of each user has independent channel fluctuation characteristic. By using this characteristic, OFDMA can achieve the multiuser diversity (MUDiv). Until this time, to achieve a low complexity and performance improvement, the adaptive subcarrier block (ASB) and frequency symbol spreading (FSS) methods have been proposed. However, the system performance in a low Eb/N0 is worse than that of maximal sum capacity (MSC) and peak to average power ratio (PAPR) does not decrease greatly. To solve these problems, in this paper, we propose the subcarrier allocation with the power priority selection (PSS) and the adaptive clipping (AC) with the peak reduction signal to improve the system and PAPR performance.
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Trinh, Le-Huy y Fabien Ferrero. "Multiband Frequency Tuneable Antennas for Selection Combining Strategy in White Space Applications". Applied Sciences 12, n.º 21 (1 de noviembre de 2022): 11062. http://dx.doi.org/10.3390/app122111062.
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This article presents a reconfigurable antenna using digitally tuneable capacitors (DTCs). Mounted on a 120 × 200 mm2 ground plane, the radiating element has very compact dimensions of 0.06λg × 0.016λg × 0.0016λg (with λg being the wavelength at 585 MHz). The proposed structure could be operated in the white-space frequency band from 470 to 700 MHz. The antenna system is composed of two radiated elements that are placed at the corner of the board. The active components were soldered onto the antennas and controlled by an embedded microcontroller via the I2C interface. Antenna impedances were simulated and evaluated by measurement with an impedance-matching bandwidth of 39.32% (470–700 MHz) for an S11 less than −6 dB. Furthermore, the numerical results show a realized maximal gain ranging from −2.2 dBi at 470 MHz to 1.87 dBi at 700 MHz. Lastly, the diversity gains based on the radiation pattern of two resonators were calculated. The results show envelope correlation coefficient (ECC) values lower than 0.5 for the different configurations.
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Marden, J. H., M. R. Wolf y K. E. Weber. "Aerial performance of Drosophila melanogaster from populations selected for upwind flight ability." Journal of Experimental Biology 200, n.º 21 (1 de noviembre de 1997): 2747–55. http://dx.doi.org/10.1242/jeb.200.21.2747.
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A computerized system for three-dimensional tracking of large numbers of individual free-flying insects was used to assess the performance of Drosophila melanogaster from populations that had undergone 160 generations of selection for upwind flight ability. Compared with control lines, the selected lines showed significant increases in mean flight velocity, decreases in angular trajectory and a significant change in the interaction between velocity and angular trajectory. Maximal flight velocity was apparent as a sharply defined upper boundary of the distribution of horizontal and vertical velocity as a function of angular trajectory; this upper bound (0.85 ms-1) differed little between the selected and control lines, although individuals from the selected lines attained maximal performance levels much more frequently. Maximum induced power output was calculated directly from the product of maximum vertical velocity and body weight. This measure (28 W kg-1 muscle) was closely predicted by a scaling relationship derived from the load-lifting limits of larger insects and vertebrates, as well as tethered D. melanogaster stimulated via their optomotor reflex to produce maximal lift. These results indicate that selection for flight performance can readily alter the relative effort and/or the frequency of phenotypes capable of attaining population-wise maximal performance levels, but shows little ability to increase population-wise maximal performance.
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Bendelac, A., P. Matzinger, R. A. Seder, W. E. Paul y R. H. Schwartz. "Activation events during thymic selection." Journal of Experimental Medicine 175, n.º 3 (1 de marzo de 1992): 731–42. http://dx.doi.org/10.1084/jem.175.3.731.
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During their differentiation in the mouse thymus, CD4+8- cells undergo several of the sequential changes observed upon normal activation of mature, peripheral CD4+ lymphocytes. Expression of CD69, an early activation marker, is first observed on a minority of cells at the T cell receptor (TCR)lo/med double-positive stage, is maximal (50-90%) on heat-stable antigen (HSA)hi TCRhi double-positive, HSAhi TCRmed CD4+8lo, and HSAhi TCRhi CD4+8- cells, and is downmodulated at the mature HSAlo CD4+8- stage. In contrast, CD44, a late activation marker, is selectively expressed at the HSAlo stage. The set of lymphokines that CD4+8- thymocytes can produce upon stimulation also characteristically expands from mainly interleukin 2 (IL-2) at the HSAhi stage, to IL-2 and very large amounts of IL-4, IL-5, IL-10, and interferon gamma (IFN-gamma) at the HSAlo stage. 1 in 30 HSAlo CD4+8- adult thymocytes secrete IL-4 upon stimulation through their TCR. This frequency is 25% of the frequency of IL-2 producers, about 100-fold above that of peripheral (mainly resting) CD4+ T cells. With time after their generation in organ culture, CD4+8- thymocytes lose their capacity to secrete IL-4, IL-5, and IFN-gamma, but not IL-2. Similarly, the frequency of IL-4, but not of IL-2, producers progressively decreases after emigration to the periphery as judged by direct comparison between thymic and splenic CD4+ cells in newborns, or by following the fate of intrathymically labeled CD4+8- cells in adults after their migration to the spleen. This sequence suggests that thymic selection results from an activation process rather than a simple rescue from death at the double-positive stage, and shows that the functional changes induced after intrathymic activation, although transient, are still evident after export to the periphery.
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GRYLLIAS, KONSTANTINOS C. y IOANNIS ANTONIADIS. "A PEAK ENERGY CRITERION (P. E.) FOR THE SELECTION OF RESONANCE BANDS IN COMPLEX SHIFTED MORLET WAVELET (CSMW) BASED DEMODULATION OF DEFECTIVE ROLLING ELEMENT BEARINGS VIBRATION RESPONSE". International Journal of Wavelets, Multiresolution and Information Processing 07, n.º 04 (julio de 2009): 387–410. http://dx.doi.org/10.1142/s0219691309002982.
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Complex Shifted Morlet Wavelets (CSMW) present a number of advantages when used for the demodulation of the vibration response of defective rolling element bearings: (A) They present the optimally located window simultaneously in the time and in the frequency domains; (B) They allow for the maximal time-frequency resolution; (C) The magnitudes of the complex wavelet coefficients in the time domain lead directly to the required envelope; (D) They allow for the optimal selection of both the center frequency and the bandwidth of the requested filter. A Peak Energy criterion (P. E.) is proposed in this paper for the simultaneous automatic selection of both the center frequency and the bandwidth of the relevant wavelet window to be used. As shown in a number of application cases, this criterion presents a more effective behavior than other criteria used (Crest Factor, Kurtosis, Smoothness Index, Number of Peaks), since it combines the advantages of energy based criteria, with criteria characterizing the spikiness of the response.
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Moiseev, A. A. "Model-based estimation of radio parameters". Radio industry 28, n.º 3 (29 de agosto de 2018): 31–45. http://dx.doi.org/10.21778/2413-9599-2018-28-3-31-45.
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It’s proposed to use model-based approach for evaluation of radiation parameters observed by passive location facilities. This method is based on model parameters adjustment and interpretation of correspondent parameters values as experimental parameters evaluations. Evaluation adequacy criterion in this case is maximal probability of overlapping of experimental and model ranges of parameters. Preliminary objects selection can be based on frequency or/end directional characteristics of received signals. A possible selection criterion is based on discrimination conditions of frequency and time ranges. The appropriate analysis is performed on the basis of the extremal analysis enabling to select ranges corresponding to observed objects. Selected ranges are transformed into time functions to be analyzed by model-based method. Therewith the frequency analysis is performed on the assumption of linear frequency modulation of the signal observed. In its turn, the amplitude analysis is based on the passive location model. Parameters are selected either by Monte-Carlo method or by direct processing of equidistant grid nodes.
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Smerlak, M. "Neutral quasispecies evolution and the maximal entropy random walk". Science Advances 7, n.º 16 (abril de 2021): eabb2376. http://dx.doi.org/10.1126/sciadv.abb2376.
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Even if they have no impact on phenotype, neutral mutations are not equivalent in the eyes of evolution: A robust neutral variant—one which remains functional after further mutations—is more likely to spread in a large, diverse population than a fragile one. Quasispecies theory shows that the equilibrium frequency of a genotype is proportional to its eigenvector centrality in the neutral network. This paper explores the link between the selection for mutational robustness and the navigability of neutral networks. I show that sequences of neutral mutations follow a “maximal entropy random walk,” a canonical Markov chain on graphs with nonlocal, nondiffusive dynamics. I revisit M. Smith’s word-game model of evolution in this light, finding that the likelihood of certain sequences of substitutions can decrease with the population size. These counterintuitive results underscore the fertility of the interface between evolutionary dynamics, information theory, and physics.
Tesis sobre el tema "Maximal frequency selection"
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Taki, Nour. "Diagnosis of Soft Faults in Complex Wired Networks". Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASG004.
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Les câbles électriques sont utilisés dans tous les secteurs pour transférer de l'énergie ou de l'information. Pendant le fonctionnement, les câbles peuvent être sujets à des défauts francs (circuit ouvert ou court-circuit) ou des défauts non-francs (endommagement de l'isolant, pincement, etc.) dus à une mauvaise utilisation, aux conditions environnementales ou au vieillissement. Ces défauts doivent être détectés à leur stade le plus précoce pour éviter une interruption de la fonction ou des conséquences plus graves. Parmi les méthodes de diagnostic des réseaux filaires qui ont été étudiées dans la littérature, la réflectométrie électrique a été considérée la plus efficace surtout dans le cas d'un défaut franc. Cependant, cette méthode s'avère moins fiable en présence d'un défaut non-franc caractérisé, généralement, par une signature de faible amplitude sur le réflectogramme qui dépend non seulement de la variation de l'impédance caractéristique du câble au niveau du défaut mais également de la configuration du signal de test telle que sa bande passante. En effet, l'augmentation de la fréquence maximale du signal de test améliore la résolution ''spatiale'' de l'information des défauts non-francs. Cependant, elle accentue, en même temps, les phénomènes d'atténuation et de dispersion du signal de test rendant ainsi la détection de ces défauts moins fiable, et surtout dans le cas des réseaux filaires complexes où la réflectométrie pourrait souffrir de problèmes d'ambiguïté liée à la localisation des défauts. Dans ce cadre, la réflectométrie distribuée où plusieurs capteurs sont installés aux extrémités du réseau sous test est appliquée entrainant l'apparition d'autres problématiques telles que le partage des ressources, la fusion de capteurs pour la prise de décision, la consommation d'énergie, etc.Dans ce contexte, cette thèse propose de développer deux approches : la première permet de choisie la meilleure fréquence maximale à appliquer au signal de test pour la détection des défauts non-francs. La seconde approche a pour objectif de choisir les capteurs les plus pertinents pour leur diagnostic dans les réseaux filaires complexes. Pour cela, une combinaison entre les données basées sur la réflectométrie et l'algorithme d'analyse en composantes principales (PCA) est utilisée. Le modèle de la PCA est développé pour détecter les défauts non francs existants. Associé à une analyse statistique basée sur Hotelling’s T² et Squared Prediction Error (SPE), les paramètres requis sont identifiés. Une étude expérimentale est réalisée, et une analyse de leurs performances en environnement bruité est effectuéeElectrical cables are used in all sectors to transfer energy or information. During operation, the cables may be subject to hard faults (open circuit, short circuit) or soft faults (isolation damage, pinching, etc.) due to misuse, environmental conditions, or aging. These faults must be detected at their earliest stage to avoid interruption of the function or more serious consequences. Even though several electric and non-electric wire diagnosis methods have been studied and developed throughout the last few decades, reflectometry-based techniques have provided effective results with hard faults. However, they have been shown to be less reliable whenever soft faults are addressed.Indeed, soft faults are characterized by a small impedance variation, resulting in a low amplitude signature on the corresponding reflectograms. Accordingly, the detection of these faults depends strongly on the test signal configuration, such as its bandwidth. Although the increase of the maximal frequency of the test signal enhances the soft fault's ''spatial'' resolution, its performance is limited by signal attenuation and dispersion. Moreover, although reflectometry offers good results in point-to-point topology networks, it suffers from ambiguity related to fault location in more complex wired networks (Multi-branched). As a solution, distributed reflectometry method, where sensors are implemented in the extremities of the network under test, is used. However, several issues are enforced, from the computing complexities and sensors fusion problems to the energy consumption.In this context, this Ph.D. dissertation proposes to develop two approaches: the first selects the best maximal frequency for soft fault detection, and the second selects the most relevant sensors to monitor and diagnose those faults in multi-branched wired networks. The proposed solution is based on a combination between reflectometry and Principal Component Analysis (PCA). The PCA model coupled with statistical analysis based on Hotelling’s T² and Squared Prediction Error (SPE) is used to detect the soft faults and select the required parameters. Experimental validation is carried out, and performance analysis in the presence of noise is investigated
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Segkos, Michail. "Advanced techniques to improve the performance of OFDM Wireless LAN". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FSegkos.pdf.
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Thesis (M.S. in Electrical Engineering and M.S. in Applied Physics)--Naval Postgraduate School, June 2004.Thesis advisor(s): Tri T. Ha, Brett H. Borden. Includes bibliographical references (p. 107-109). Also available online.
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Chi, Xuan. "The Impact of Channel Estimation Error on Space-Time Block and Trellis Codes in Flat and Frequency Selective Channels". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/33963.
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Recently multiple antenna systems have received significant attention from researchers as a means to improve the energy and spectral efficiency of wireless systems. Among many classes of schemes, Space-Time Block codes (STBC) and Space-Time Trellis codes (STTC) have been the subject of many investigations.Both techniques provide a means for combatting the effects of multipath fading without adding much complexity to the receiver. This is especially useful in the downlink of wireless systems. In this thesis we investigate the impact of channel estimation error on the performance of both STBC and STTC.
Channel estimation is especially important to consider in multiple antenna systems since (A) for coherent systems there are more channels to estimate due to multiple antennas and (B) the decoupling of data streams relies on correct channel estimation. The latter effect is due to the intentional cross-talk introduced into STBC.
Master of Science
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Aldosari, Mansour. "Design and analysis of green mobile communication networks". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/design-and-analysis-of-green-mobile-communication-networks(37b5278a-45da-4a81-b89c-54c7d876586a).html.
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Increasing energy consumption is a result of the rapid growth in cellular communication technologies and a massive increase in the number of mobile terminals (MTs) and communication sites. In cellular communication networks, energy efficiency (EE) and spectral efficiency (SE) are two of the most important criteria employed to evaluate the performance of networks. A compromise between these two conflicting criteria is therefore required, in order to achieve the best cellular network performance. Fractional frequency reuse (FFR), classed as either strict FFR or soft frequency reuse (SFR), is an intercell interference coordination (ICIC) technique applied to manage interference when more spectrum is used, and to enhance the EE. A conventional cellular model's downlink is designed as a reference in the presence of inter-cell interference (ICI) and a general fading environment. Energy-efficient cellular models,such as cell zooming, cooperative BSs and relaying models are designed, analysed and compared with the reference model, in order to reduce network energy consumption without degrading the SE. New mathematical models are derived herein to design a distributed antenna system (DAS), in order to enhance the system's EE and SE. DAS is designed in the presence of ICI and composite fading and shadowing with FFR. A coordinate multi-point (CoMP) technique is applied, using maximum ratio transmission (MRT) to serve the mobile terminal (MT), with all distributed antenna elements (DAEs), transmit antenna selection (TAS) being applied to select the best DAE and general selection combining (GSC) being applied to select more than one DAE. Furthermore, a Cloud radio access network (C-RAN) is designed and analysed with two different schemes, using the high-power node (HPN) and a remote radio head (RRH), in order to improve the EE and SE of the system. Finally, a trade-off between the two conflicting criteria, EE and SE, is handled carefully in this thesis, in order to ensure a green cellular communication network.
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Ben, Salem Aymen. "The Application of Multiuser Detection to Spectrally Efficient MIMO or Virtual MIMO SC-FDMA Uplinks in LTE Systems". Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/30351.
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Single Carrier Frequency Division Multiple Access (SC-FDMA) is a multiple access transmission scheme that has been adopted in the 4th generation 3GPP Long Term Evolution (LTE) of cellular systems. In fact, its relatively low peak-to-average power ratio (PAPR) makes it ideal for the uplink transmission where the transmit power efficiency is of paramount importance. Multiple access among users is made possible by assigning different users to different sets of non-overlapping subcarriers. With the current LTE specifications, if an SC-FDMA system is operating at its full capacity and a new user requests channel access, the system redistributes the subcarriers in such a way that it can accommodate all of the users. Having less subcarriers for transmission, every user has to increase its modulation order (for example from QPSK to 16QAM) in order to keep the same transmission rate. However, increasing the modulation order is not always possible in practice and may introduce considerable complexity to the system. The technique presented in this thesis report describes a new way of adding more users to an SC-FDMA system by assigning the same sets of subcarriers to different users. The main advantage of this technique is that it allows the system to accommodate more users than conventional
SC-FDMA and this corresponds to increasing the spectral efficiency without requiring a higher modulation order or using more bandwidth. During this work, special attentions wee paid to the cases where two and three source signals are being transmitted on the same set of subcarriers, which leads respectively to doubling and tripling the spectral efficiency. Simulation results show that by using the proposed technique, it is possible to add more users to any SC-FDMA system without increasing the bandwidth or the modulation order while keeping the same performance in terms of bit error rate (BER) as the conventional SC-FDMA. This is realized by slightly increasing the energy per bit to noise power spectral density ratio (Eb/N0) at the transmitters.
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Wang, Chao. "Exploiting non-redundant local patterns and probabilistic models for analyzing structured and semi-structured data". Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1199284713.
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Rakshith, M. R. "Algorithms For Spatial Modulation Systems". Thesis, 2013. http://etd.iisc.ac.in/handle/2005/3905.
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It is well known that multiple antennas at the transmitter and receiver are imperative for reliable and high data-rate communication over wireless channels. However, these systems essentially need multiple radio frequency (RF) chains owing to multiple antennas, and hence pose challenges for applications with limited form-factor. Antenna Selection (AS) techniques alleviate this problem by using only a subset of the total available antennas and hence require only a few RF chains compared to the number of antennas. These systems operate in a closed-loop scenario, where the information fed back from the receiver is used for the transmit antenna subset selection. In contrast to this, a novel open-loop technique known as spatial modulation (SM) was recently proposed that uses a single RF-chain at the transmitter and achieves a higher spectral efficiency compared to single-input and AS based systems. The work in the thesis mainly focuses on the following aspects of SM system:
Study of Mutual Information in SM systems operating in open-loop and closed-loop
scenarios: We study the achievable mutual information in the SM system operating with finite and Gaussian input alphabet, and compare the results with that of the SIMO and AS based systems.
Reduced-complexity maximum-likelihood (ML) decoding algorithms for SM systems: We propose ML-optimal sphere decoders for SM systems with arbitrary number of transmit antennas. Furthermore, a reduced-complexity ML detector is also proposed whose computational complexity is lowest among the known existing detectors in the literature.
Transmit diversity techniques for SM systems: The conventional SM system achieves a transmit diversity order of one. We propose a complex interleaved orthogonal design baaed SM scheme that achieves a transit diversity order of two, while offering symbol-by- symbol ML decodability.
Transmit antenna subset selection algorithms for SM systems: The SM system is considered in the closed-loop scenario, where only a subset of the total number of transmit antennas is chosen based on the information fed back by the receiver. Specifically, the Euclidean distance and capacity optimized antenna selection algorithms are studied in comparison with the conventional AS based systems.
SM system operating in dispersive channels: The SM system operating in a dispersive channel with the aid of zero-padding is studied. It is shown that the SM system achieves full receive-diversity and multipath-diversity with ML decoding, but offers a decoding complexity that is exponential in the number of multipaths. Furthermore, a reduced complexity linear receiver is proposed that achieves achieves full multipath as well as receive-diversity, while offering a decoding complexity order same as that of the SM system operating in a frequency-flat channel.
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Rakshith, M. R. "Algorithms For Spatial Modulation Systems". Thesis, 2013. http://etd.iisc.ernet.in/2005/3905.
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It is well known that multiple antennas at the transmitter and receiver are imperative for reliable and high data-rate communication over wireless channels. However, these systems essentially need multiple radio frequency (RF) chains owing to multiple antennas, and hence pose challenges for applications with limited form-factor. Antenna Selection (AS) techniques alleviate this problem by using only a subset of the total available antennas and hence require only a few RF chains compared to the number of antennas. These systems operate in a closed-loop scenario, where the information fed back from the receiver is used for the transmit antenna subset selection. In contrast to this, a novel open-loop technique known as spatial modulation (SM) was recently proposed that uses a single RF-chain at the transmitter and achieves a higher spectral efficiency compared to single-input and AS based systems. The work in the thesis mainly focuses on the following aspects of SM system:
Study of Mutual Information in SM systems operating in open-loop and closed-loop
scenarios: We study the achievable mutual information in the SM system operating with finite and Gaussian input alphabet, and compare the results with that of the SIMO and AS based systems.
Reduced-complexity maximum-likelihood (ML) decoding algorithms for SM systems: We propose ML-optimal sphere decoders for SM systems with arbitrary number of transmit antennas. Furthermore, a reduced-complexity ML detector is also proposed whose computational complexity is lowest among the known existing detectors in the literature.
Transmit diversity techniques for SM systems: The conventional SM system achieves a transmit diversity order of one. We propose a complex interleaved orthogonal design baaed SM scheme that achieves a transit diversity order of two, while offering symbol-by- symbol ML decodability.
Transmit antenna subset selection algorithms for SM systems: The SM system is considered in the closed-loop scenario, where only a subset of the total number of transmit antennas is chosen based on the information fed back by the receiver. Specifically, the Euclidean distance and capacity optimized antenna selection algorithms are studied in comparison with the conventional AS based systems.
SM system operating in dispersive channels: The SM system operating in a dispersive channel with the aid of zero-padding is studied. It is shown that the SM system achieves full receive-diversity and multipath-diversity with ML decoding, but offers a decoding complexity that is exponential in the number of multipaths. Furthermore, a reduced complexity linear receiver is proposed that achieves achieves full multipath as well as receive-diversity, while offering a decoding complexity order same as that of the SM system operating in a frequency-flat channel.
Capítulos de libros sobre el tema "Maximal frequency selection"
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Borms, Samuel, Kris Boudt, Frederiek Van Holle y Joeri Willems. "Semi-supervised Text Mining for Monitoring the News About the ESG Performance of Companies". En Data Science for Economics and Finance, 217–39. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66891-4_10.
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AbstractWe present a general monitoring methodology to summarize news about predefined entities and topics into tractable time-varying indices. The approach embeds text mining techniques to transform news data into numerical data, which entails the querying and selection of relevant news articles and the construction of frequency- and sentiment-based indicators. Word embeddings are used to achieve maximally informative news selection and scoring. We apply the methodology from the viewpoint of a sustainable asset manager wanting to actively follow news covering environmental, social, and governance (ESG) aspects. In an empirical analysis, using a Dutch-written news corpus, we create news-based ESG signals for a large list of companies and compare these to scores from an external data provider. We find preliminary evidence of abnormal news dynamics leading up to downward score adjustments and of efficient portfolio screening.
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Mekler, Philipp y Jingshu Sun. "Pharma Tender Processes: Modeling Auction Outcomes". En Quantitative Models in Life Science Business, 51–71. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11814-2_4.
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AbstractThis chapter summarizes the overall tendering and contracting process in the pharmaceutical industry by providing an overview of the first-sealed price auction theory, auction rules, and drug pricing mechanism of different countries. Comparing procurement systems across Asia, Africa, Europe, and Latin America, the review casts light on various pharmaceutical bidding systems across the world and their impact on drug prices. Then, this review focuses on the empirical estimation of first-price auction models. In terms of model specification, we compare the two most commonly used empirical methods for bidding price estimation: structural models and reduced form approaches to test the auction theory. Maximum likelihood estimation is the most frequently used method for structural estimation in literature and selection bias correction is widely adopted using reduced form models. In addition to parametric model construction, we also provide an extensive introduction of non-parametric testing methodologies, including non-parametric estimation and quantile-based estimation to reduce the computation complexity and further illustrate how auction theory could be validated by real-world applications. Additional thoughts and adjustments on non-parametric testing are brought up based on a real-world tendering use case from a large multi-national pharmaceutical company.
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Greenlaw, Raymond, H. James Hoover y Walter L. Ruzzo. "Greedy Algorithms". En Limits to Parallel Computation. Oxford University Press, 1995. http://dx.doi.org/10.1093/oso/9780195085914.003.0011.
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We consider the selection of two basketball teams at a neighborhood playground to illustrate the greedy method. Usually the top two players are designated captains. All other players line up while the captains alternate choosing one player at a time. Usually, the players are picked using a greedy strategy. That is, the captains choose the best unclaimed player. The system of selection of choosing the best, most obvious, or most convenient remaining candidate is called the greedy method. Greedy algorithms often lead to easily implemented efficient sequential solutions to problems. Unfortunately, it also seems to be that sequential greedy algorithms frequently lead to solutions that are inherently sequential — the solutions produced by these algorithms cannot be duplicated rapidly in parallel, unless NC equals P. In the following subsections we will examine this phenomenon. We illustrate some of the important aspects of greedy algorithms using one that constructs a maximal independent set in a graph. An independent set is a set of vertices of a graph that are pairwise nonadjacent. A maximum independent set is such a set of largest cardinality. It is well known that finding maximum independent sets is NP-hard. An independent set is maximal if no other vertex can be added while maintaining the independent set property. In contrast to the maximum case, finding maxima? independent sets is very easy. Figure 7.1.1 depicts a simple polynomial time sequential algorithm computing a maximal independent set. The algorithm is a greedy algorithm: it processes the vertices in numerical order, always attempting to add the lowest numbered vertex that has not yet been tried. The sequential algorithm in Figure 7.1.1, having processed vertices 1,... , j -1, can easily decide whether to include vertex j. However, notice that its decision about j potentially depends on its decisions about all earlier vertices — j will be included in the maximal independent set if and only if all j' less than j and adjacent to it were excluded.
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"Induction Heating Power Supplies". En Elements of Induction Heating, 47–75. ASM International, 1988. http://dx.doi.org/10.31399/asm.tb.eihdca.t65220047.
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Abstract Besides the induction coil and workpiece, the induction generator (source of ac power) is probably the most important component of an overall induction heating system. Such equipment is typically rated in terms of its frequency and maximum output power (in kilowatts). This chapter addresses the selection of power supplies in terms of these two factors as well as the operational features of different types of sources. The six different types of power supplies for induction heating applications covered in this chapter are line-frequency supplies, frequency multipliers, motor-generators, solid-state (static) inverters, spark-gap converters, and radio-frequency power supplies. The chapter discusses the design and characteristics of each of the various types of power supplies.
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Ahmad, Ishfaq, Alam Zeb Khan, Mirza Barjees Baig y Ibrahim M. Almanjahie. "Flood Frequency Analysis Using Bayesian Paradigm". En Advances in Environmental Engineering and Green Technologies, 84–103. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-5225-9771-1.ch005.
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At-site flood frequency analysis (FFA) of extreme hydrological events under Bayesian paradigm has been carried out and compared with frequentist paradigm of maximum likelihood estimation (MLE). The main objective of this chapter is to identify the best approach between Bayesian and frequentist one for at-site FFA. As a case study, the data of only two stations were used, Kotri and Rasul, and Bayesian and MLE approaches were implemented. Most commonly used tests were applied for checking initial assumptions. Goodness of fit (GOF) tests were used to identify the best model, which indicated that the generalized extreme value (GEV) distribution appeared to be best fitted for both stations. Under Bayesian paradigm, quantile estimates are constructed using Markov Chain Monte Carlo (MCMC) simulation method for their respective returned periods and non-exceedance probabilities. For MCMC simulations, as compared to other sampler, the M-H sampling technique was used to generate a large number of parameters. The analysis indicated that the standard errors of the parameters' estimates and ultimately the quantiles' estimates using Bayesian methods remained less as compared to maximum likelihood estimation (MLE), which shows the superiority of Bayesian methods over conventional ones in this study. Further, the safety amendments under two techniques were also calculated, which also show the robustness of Bayesian method over MLE. The outcomes of these analyses can be used in the selection of better design criteria for water resources management, particularly in flood mitigation.
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"Selection of flood frequency model in Niger Basin using maximum likelihood method". En Water and Urban Development Paradigms, 355–60. CRC Press, 2008. http://dx.doi.org/10.1201/9780203884102-53.
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Agbede, O., J. Adewumi, J. Akinyemi y G. Bolaji. "Selection of flood frequency model in Niger Basin using maximum likelihood method". En Water and Urban Development Paradigms, 337–42. CRC Press, 2008. http://dx.doi.org/10.1201/9780203884102.ch42.
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Hari, Riitta y Aina Puce. "Visual Responses". En MEG-EEG Primer, editado por Riitta Hari y Aina Puce, 214–26. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190497774.003.0013.
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This chapter introduces visual evoked responses. Transient VEPs are maximal across the posterior scalp and consist of three main deflections—N75, P100, and N135. Magnetic VEFs also show a prominent occipital response peaking at around 100 ms. Visual stimulation can include light flashes, pattern onset/offsets, pattern reversals and natural images. The extent and eccentricity of the visual stimulus can selectively encompass foveal or extrafoveal regions, or include quadrants, hemifield or the entire visual field. Stimulus attributes such as visual angle, spatial frequency, luminance and contrast greatly affect VEF and VEP amplitudes and latencies. Selective responses in the dorsal and ventral visual streams can be elicited with carefully chosen stimuli. Steady-state responses to periodically varying visual stimuli can be used to frequency-tag different aspects of the visual stimulus.
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Prakash, S. P. Shiva, T. N. Nagabhushan y Kirill Krinkin. "Congestion Avoidance and Delay Minimization in Energy Aware Routing of Dynamic ieee 802.11s WMN". En Cognitive Analytics, 164–93. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-2460-2.ch010.
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Minimization of delay in collecting the data at any base stations is one of the major concerns in cluster based Wireless Mesh Networks. several researches have proposed algorithms to control congestion considering static nature of a node. Mobility of a node results in high congestion due to frequent link breakages and high energy consumption due to re-establishment of route during routing process. Hence, the authors consider dynamic nodes with single hop inside the static cluster. The proposed model includes four modules namely, Cluster head selection, slot allocation, slot scheduling and data collection process. the cluster head selection is based on the maximum energy, number of links and link duration. Slot allocation is based on the available energy () and the required energy (). Slot scheduling is carried out based on the link duration. Data at the base station will be collected as they are scheduled. Model is tested using Network Simulator-3 (NS3) and results indicate that the proposed model achieves least delay besides reducing the congestion compared to the existing methods.
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Gu, Bo y Osamu Mizuno. "Application of Game Theory for Network Recovery After Large-Scale Disasters". En Smart Technologies for Emergency Response and Disaster Management, 223–42. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2575-2.ch008.
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In recent years, large-scale disasters took place frequently and always caused severe damages to the network infrastructures. Due to these damages, available network resources are usually not sufficient to meet the data transmission requirements of users after disasters. Moreover, users tend to behave selfishly by consuming as much network resources as possible. Incentive mechanisms are therefore essential for the users to voluntarily cooperate with each other and improve the system performance. In commercial networks, this can be efficiently achieved through pricing. Namely, by selecting an appropriate pricing policy, it is able to incentivize users to choose the service that best matches their data transmission demands. In this chapter, assuming that a time-dependent pricing scheme is imposed on network users, a Stackelberg leader-follower game is then formulated to study the joint utility optimization problem of the users in a disaster region subject to maximum delay and storage constrains. The equilibrium for the Stackelberg leader-follower game is also investigated.
Actas de conferencias sobre el tema "Maximal frequency selection"
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Khan, Muhammad Umar, Anila Kousar, Mehboob Alam y Yehia Massoud. "Frequency Selective Light Scattering and Absorption for Maximum Energy Harvesting". En 2019 31st International Conference on Microelectronics (ICM). IEEE, 2019. http://dx.doi.org/10.1109/icm48031.2019.9021275.
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Collins, Timothy M. y Mohammad Robiul Hossan. "Radio Frequency and Microwave Power Absorption in Spherical Shaped Objects". En ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71334.
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Microwave and radio frequency heating has great promise in many engineering and biomedical applications because of its non-contact, volumetric selective heating. However, the heating patterns and temperature distributions are non-uniform due to non-uniform electromagnetic power absorptions. In this study, we present a closed-form analytic expression of electromagnetic field distribution and power absorption in a spherical shaped object. A simplified Maxwell’s equation that represents plane wave is solved in spherical coordinates using vector potentials and separation of variables. The electromagnetic power absorption is obtained from the electromagnetic field distribution within the object using Poynting theorem. The analytical expressions of the electric field and power generation are evaluated for meat balls of 1.0, 2.0, 3.0 and 5.0 cm radii and two different electromagnetic frequencies. Results show that the strength of the absorbed electromagnetic wave and power absorption is highly dependent on the radius of the dielectric sphere. The presence of local maxima of electric and magnetic field strength due to the constructive interference of the reflection and transmission of electromagnetic wave in the target object are found in all sizes. However numbers of peaks or valleys are more in larger meat balls. The spatial distribution of microwave power absorption follows the trend of electromagnetic field distribution. The positions of local maxima and minima of power absorption and electromagnetic field distributions vary with the radius of the sphere and applied frequencies. It indicates that the uniform and effective electromagnetic power absorption can be facilitated by the proper design of the object of interest and selection of an appropriate frequency.
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Al-Dweik, A., R. Hamila, L. Samara y O. Filio-Rodriguez. "Maximum likelihood detection of precoded SFBC in frequency-selective fading channels". En 2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC). IEEE, 2017. http://dx.doi.org/10.1109/pimrc.2017.8292612.
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Nam, Woosung, Ju-Young Shin, Hongjoon Shin y Jun-Haeng Heo. "Selection of Variables for Regional Frequency Analysis of Annual Maximum Precipitation Using Multivariate Techniques". En World Environmental and Water Resources Congress 2007. Reston, VA: American Society of Civil Engineers, 2007. http://dx.doi.org/10.1061/40927(243)411.
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Shi, Zhenning y Mark C. Reed. "Iterative Maximal Ratio Combining Channel Estimation for Multiuser Detection on a Time Frequency Selective Wireless CDMA Channel". En 2007 IEEE Wireless Communications and Networking Conference. IEEE, 2007. http://dx.doi.org/10.1109/wcnc.2007.190.
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Jin, Yaqiang, Zhiliang Liu, Jinlong Kang, Jie Yin y Dandan Peng. "Frequency Band Selection Based on a New Indicator: Accuracy Rate". En ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71340.
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Local defects in rotating machinery give rise to periodic impulses in vibrations. In order to acquire the information of these faults, various diagnostic methods have been proposed in the past decades. Most methods used the squared envelope spectrum (i.e., the spectrum of the squared envelope) as the final diagnostic tool, but different preprocessing steps were used before obtaining the envelope signal. The key problem is to obtain the center frequency and bandwidth of the fault signal, then analyze the envelope (squared envelope spectrum) of the band-pass filtered signal. The framework of accuracy rate method was proposed by means of cross validation of the nearest neighbor classifier in this paper: a) obtain the piecewise signal through original signal segmentation; b) calculate the feature of each piecewise signal; c) then an accuracy rate is calculated based on cross validation of the nearest neighbor classifier; and d) repeat the above steps in different frequency band, then find a frequency band with the maximum accuracy rate. Through this algorithm, we can obtain a fault frequency band, and then we can find out the type of the fault by the spectrum of the squared envelope. At the end of this paper, the proposed method is validated by two examples and compared with the other two diagnostic methods: conventional envelope analysis and Fast kurtogram. Through the comparison of results, the validity and superiority of this method has been proved.
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Lakshmanan, M. K., I. Budiarjo y H. Nikookar. "Maximally Frequency Selective Wavelet Packets Based Multi-Carrier Modulation Scheme for Cognitive Radio Systems". En IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference. IEEE, 2007. http://dx.doi.org/10.1109/glocom.2007.796.
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Ketseoglou, Thomas y Meghana Gaikwad. "Approximate Maximum Likelihood Detection of SDMA OFDM over Unknown Time-Varying Frequency-Selective Channels". En 2006 Wireless Telecommunications Symposium. IEEE, 2006. http://dx.doi.org/10.1109/wts.2006.334548.
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Le, Ly-Minh-Duy y Kah Chan Teh. "Maximum-likelihood FFH/MFSK receiver with MTJ and PBNJ over frequency-selective Rayleigh fading channels plus timing and frequency offsets". En 2013 9th International Conference on Information, Communications & Signal Processing (ICICS). IEEE, 2013. http://dx.doi.org/10.1109/icics.2013.6782844.
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Rahimian, N. y A. Iravani. "Reduced-Complexity Novel Ordering for Group Maximum Likelihood Detection in MIMO Frequency Selective Fading Channels". En 2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications (ISSSTA). IEEE, 2008. http://dx.doi.org/10.1109/isssta.2008.140.
Texto completoInformes sobre el tema "Maximal frequency selection"
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Whitaker, Stephen. Rocky intertidal community monitoring at Channel Islands National Park: 2018–19 annual report. National Park Service, agosto de 2023. http://dx.doi.org/10.36967/2299674.
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Channel Islands National Park includes the five northern islands off the coast of southern California (San Miguel, Santa Rosa, Santa Cruz, Anacapa, and Santa Barbara Islands) and the surrounding waters out one nautical mile. There are approximately 176 miles of coastline around the islands, about 80% of which is composed of rock. The diversity and undisturbed nature of the tidepools of this rocky coastline were recognized as special features of the islands in the enabling legislation. To conserve these communities unimpaired for future generations, the National Park Service has been monitoring the rocky intertidal communities at the islands since 1982. Sites were established between 1982 and 1998. Site selection considered visitation, accessibility, presence of representative organisms, wildlife disturbance, and safety. This report summarizes the 2018–2019 sampling year efforts (from November 2018 to April 2019) and findings of the Channel Islands National Park Rocky Intertidal Community Monitoring Program. Specific monitoring objectives are 1) to determine the long-term trends in percent cover of key sessile organisms in the rocky intertidal ecosystem, and 2) to determine population dynamics of black abalone (Haliotis cracherodii), owl limpets (Lottia gigantea), and ochre sea stars (Pisaster ochraceus). Objectives were met by monitoring percent cover of core species in target intertidal zones using photoplots and transects, and by measuring size frequency and abundance of black abalone, owl limpets, and sea stars using fixed plots or timed searches. Twelve key species or assemblages, as well as the substrate, tar, have been monitored twice per year at 21 sites on the five park islands as part of the rocky intertidal community monitoring program. Fixed photoplots were used to monitor the percent cover of thatched and acorn barnacles (Tetraclita rubescens, Balanus glandula/Chthamalus spp., respectively), mussels (Mytilus californianus), rockweeds (Silvetia compressa, and Pelvetiopsis californica (formerly Hesperophycus californicus), turfweed (Endocladia muricata), goose barnacles (Pollicipes polymerus) and tar. Point-intercept transects were used to determine the percent cover of surfgrass (Phyllospadix spp.). Information about size distribution (i.e., “size frequency” data) was collected for owl limpets in circular plots. Size distribution and relative abundance of black abalone and ochre sea stars were determined using timed searches. The maximum number of shorebirds and pinnipeds seen at one time were counted at each site. The number of concession boat visitors to the Anacapa tidepools was collected and reported. All sites were monitored in 2018–2019. This was the third year that we officially reduced our sampling interval from twice per year (spring and fall) to once in order to streamline the program and allow for the implementation of additional protocols. Weather conditions during the site visits were satisfactory, but high wind coupled with strong swell and surge limited or prevented the completion of some of the abalone and sea star searches. The percent cover for most key species or assemblages targeted in the photoplots was highly variable among sites. Mussel (Mytilus californianus) cover remained below average at Anacapa and Santa Barbara Islands. Record or near record low abundances for Mytilus were measured at Middle West Anacapa (Anacapa Island), Harris Point (San Miguel Island), Prisoner’s Harbor (Santa Cruz Island), and Sea Lion Rookery (Santa Barbara Island) sites. The only site that appeared to have above average Mytilus cover was Scorpion Rock on Santa Cruz Island. All other sites had mussel cover near or below the long-term mean. Qualitatively, Mytilus recruitment appeared low at most sites. Both rockweed species, Silvetia compressa and Pelvetiopsis californica (formerly Hesperophycus californicus), continued to decrease markedly in abundance this year at the majority of sites compared to combined averages for previous years. Fossil Reef and Northwest-Talcott on Santa Rosa Island, Sea Lion Rookery on Santa Barbara Island, and South Frenchy’s Cove on Anacapa Island were the only sites that supported Silvetia cover that was near the long-term mean. No sites exhibited above average cover of rockweed. Extremely high levels of recruitment for Silvetia and Pelvetiopsis were documented at many sites. Most sites exhibited marked declines in S. compressa abundances beginning in the early 2000s, with little recovery observed for the rockweed through this year. Barnacle (Chthamalus/Balanus spp.) cover fell below the long-term means at all islands except Anacapa, where barnacle cover was slightly above average. Endocladia muricata abundances remained comparable to the grand mean calculated for previous years at Santa Barbara, Santa Cruz, and Santa Rosa Islands, while cover of the alga decreased slightly below the long-term means at Anacapa and San Miguel Islands. Black abalone (Haliotis cracherodii) abundances at the islands remain less than one percent of 1985 population levels. Zero abalone were found throughout the entire site at Landing Cove on Santa Barbara Island and South Frenchy’s Cove on Anacapa Island. Above average abundances relative to the long-term mean generated from post-1995 data were observed at all but five sites. Juvenile black abalone were seen at all islands except Santa Barbara. Ochre sea star (Pisaster ochraceus) populations crashed in 2014 at all monitoring sites due to Sea Star Wasting Syndrome, an illness characterized by a suite of symptoms that generally result in death. The mortality event was widely considered to be the largest mortality event for marine diseases ever seen. Beginning in June 2013, the disease swiftly and significantly impacted P. ochraceus (among other species of sea stars) populations along the North American Pacific coast from Alaska to Baja California, Mexico. By the beginning of 2014, P. ochraceus abundances had declined by >95% at nearly all Channel Islands long-term intertidal monitoring sites, in addition to numerous other locations along the West Coast. At various times during the past decade, extremely high abundances (~ 500 P. ochraceus) have been observed at multiple sites, and most locations have supported >100 sea stars counted during 30-minute site-wide searches. This year, abundances ranged 0–13 individuals per site with all but one site having fewer than 10 P. ochraceus seen during routine searches. Insufficient numbers of sea stars were seen to accurately estimate the size structure of P. ochraceus populations. Only two juveniles (i.e., <50 mm) were observed at all sites combined. Giant owl limpet densities in 2018–2019 were comparable or slightly above the long-term mean at seven sites. Exceptionally high densities were measured at Northwest-Talcott on Santa Rosa Island, Otter Harbor on San Miguel Island, and Willows Anchorage on Santa Cruz Island. The sizes of L. gigantea this year varied among sites and islands. The smallest L. gigantea were observed at Otter Harbor followed closely by Willows Anchorage and Anacapa Middle West, and the largest were seen at Northwest-Talcott. Temporally, the mean sizes of L. gigantea in 2018–2019 decreased below the long-term mean at each island except Anacapa. Surfgrasses (Phyllospadix spp.) are typically monitored biannually at two sites each on Santa Cruz and Santa Rosa Islands. Beginning in 2015, all transects at each of the monitoring sites were only sampled once per year. At East Point on Santa Rosa Island, the conditions were not conducive to sampling the surfgrass transects, but qualitatively, percent cover of surfgrass appeared to be near 100% on all three transects. Relative to past years, cover of surfgrass increased above the long-term mean at Fraser Cove on Santa Cruz Island, fell slightly below the mean at Trailer on Santa Cruz Island, and remained approximately equivalent to the mean at the two Santa Rosa Island sites. Overall, the abundance and diversity of shorebirds in 2018–2019 at all sites appeared similar to observations made in recent years, with the exception of elevated numbers of brown pelicans (Pelecanus occidentalis) observed at East Point on Santa Rosa Island. Black oystercatchers (Haematopus bachmani) were the most ubiquitous shorebird seen at all sites. Black turnstones (Arenaria melanocephala) were not common relative to past years. Pinniped abundances remained comparable in 2018–2019 to historical counts for all three species that are commonly seen at the islands. Harbor seals (Phoca vitulina) were seen in the vicinity of eight sites this year. As in past years, harbor seals were most abundant at Otter Harbor and Harris Point on San Miguel Island. Elephant seals (Mirounga angustirostris) were seen at six sites during the year, where abundances ranged 1–5 individuals per location. California sea lions (Zalophus californianus) were common at Santa Barbara Island; 117 individuals were observed at Sea Lion Rookery. Sea lion abundances were higher than usual at Harris Point (N = 160) and Otter Harbor (N = 82) on San Miguel Island. Relative to past years, abundances this year were considered average at other locations.