Results 81 to 90 of about 4,468,856 (284)

Frequency hopping modulation recognition based on time-frequency energy spectrum texture feature

open access: yesTongxin xuebao, 2019
For frequency hopping modulation identification,a novel method based on time-frequency energy spectrum texture feature was proposed.Firstly,the time-frequency diagram of the frequency hopping signal was obtained by smoothed pseudo Wigner-Ville ...
Hongguang LI   +3 more
doaj   +2 more sources

Signal enhancement by time-frequency peak filtering

open access: yes, 2003
Time-frequency peak filtering (TFPF) allows the reconstruction of signals from observations corrupted by additive noise by encoding the noisy signal as the instantaneous frequency (IF) of a frequency modulated (FM) analytic signal.
Boashash, Boualem   +3 more
core   +1 more source

When Poor Exciton Dissociation Limits Photocurrents in Organic Solar Cells: Why Low Offset Non‐Fullerene Acceptor Blends Can't Be Efficient

open access: yesAdvanced Materials, EarlyView.
The energetic offset between the donor and the acceptor components in organic photoactive layers is central to the tradeoff between photovoltage and photocurrent losses. This Perspective covers the most important issues surrounding this topic in non‐fullerene acceptor blends, from the difficulty of accurately determining state energies and driving ...
Dieter Neher, Manasi Pranav
wiley   +1 more source

Resistance to Overdoping Allows Over 2000 S cm−1 Conductivity in P(g3BTTT) With Anion‐Exchange Doping

open access: yesAdvanced Materials, EarlyView.
Anion‐exchange doping of conjugated polymers is an effective way to achieve high conductivities. Here, we report over 2000 S cm−1 electrical conductivity for doped P(g3BTTT). In addition, we show that P(g3BTTT) sustains exceptionally high doping levels without any drop in the charge mobility.
Basil Hunger   +14 more
wiley   +1 more source

Organic Materials of Tomorrow: Horizons of Artificial Intelligence

open access: yesAdvanced Materials, EarlyView.
This review examines machine learning techniques accelerating the discovery of organic semiconductors by linking molecular structure to properties. Key methods include graph neural networks, generative models, and active learning. Applications to organic photovoltaics demonstrate practical impact.
Harold Mena   +3 more
wiley   +1 more source

Frequency-hopping Signals Analysis Based on FPGA

open access: yesProceedings of the 2nd International Conference on Computer Application and System Modeling, 2012
A method which bases on FPGA to realize the frequency-hopping (FH) signal analysis system is proposed. It designs a Radix-4 DIT FFT processing unit circuit firstly, then makes a Short-Time Fourier Transform(STFT) to FH signal and gets spectrum amplitude values.
Yan Gao   +4 more
openaire   +1 more source

Low-Complexity Reduced-Rank Adaptive Detection in Hybrid Direct-Sequence Time-Hopping Ultrawide Bandwidth Systems

open access: yes, 2009
— In this contribution reduced-rank adaptive minimum mean-square error multiuser detector (MMSE-MUD) is proposed and investi-gated for the hybrid direct-sequence time-hopping ultrawide bandwidth (DS-TH UWB) systems.
Ahmed, Qasim   +3 more
core   +1 more source

Why Is the Mechanism Underlying the Chiral‐Induced Selectivity Effect Still Challenging?

open access: yesAdvanced Materials, EarlyView.
The chiral‐induced spin selectivity (CISS) effect is observed in many experimental configurations and for different materials. However, there are theoretical challenges in attempting to explain those results. A qualitative framework for explaining all the results is presented.
Ron Naaman, Yossi Paltiel
wiley   +1 more source

Rethinking Charge Transport and Recombination in Donor‐Diluted Organic Solar Cells

open access: yesAdvanced Materials, EarlyView.
Organic solar cells with 1–45% PM6 content in Y12 were studied to link structure and charge dynamics to performance. The conductivity follows a 3D percolation model without a sharp threshold. Donor dilution preserves the photogeneration yield, but limits the fill factor due to transport resistance losses.
Chen Wang   +14 more
wiley   +1 more source

Software-Defined-Radio-Assisted Adaptive Broadband Frequency Hopping Multicarrier DS-CDMA

open access: yes, 2002
Against the backdrop of the explosive expansion of the Internet and the continued dramatic increase in demand for high-speed multimedia wireless services, there is an urgent demand for flexible, bandwidth-efficient transceivers.
Yang, L-L., Hanzo, L.
core   +1 more source

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