Decoder-based transient signal post-processing for ITU-T G.719 at low bit rate

Associated with ITU-T G.719,a post-processing method in frequency domain for enhancing the perceptual quality of the decoded transient audio is proposed only to the audio decoder with no side information from the encoder.The proposed post-filter is used to filter the frequency coefficients of the decoded transient frame and consists of a short-term post-filter and a spectral tilt compensation filter which are derived from linear predictive coding（LPC） predictor based on the discrete cosine transform（DCT） coefficients of the decoded transient frame.As a result,the post-filter in frequency domain shapes the temporal noise in time domain and controls the pre-echo noise effectively while enhancing the transient perception.Listening test results show that the preferring ratio of the post-processed transient signal is higher than that of the original decoded signal at a low bit rate of 32 kbit/s in G.719 and the post-processing module brings a complexity of 12.399 WMOPS to the decoder.

Accurate Gain Flattening Filters Manufactured by Optical Compensation Monitoring Method

GFFs with less than 0.4 dB peak-to-peak error functions are routinely fabricated using commercially available coating machines by utilizing the natural error compensation mechanism of wavelength variable turning point optical monitoring method.

Event-triggered predefined-time control for full-state constrained nonlinear systems: A novel command filtering error compensation method

In this paper, a command filter-based adaptive fuzzy predefined-time event-triggered tracking control problem is investigated for uncertain nonlinear systems with time-varying full-state constraints. By designing a sliding mode differentiator, the inherent computational complexity problem within the predefined-time backstepping framework is solved. Different from the existing command filter-based finite-time and fixed-time control strategies that the convergence time of the filtering error is adjusted through the system initial value or numerous parameters, a novel command filtering error compensation method is presented,which tunes one control parameter to make the filtering error converge in the predefined time, thereby reducing the complexity of design and analysis of processing the filtering error. Then, an improved event-triggered mechanism(ETM) that builds upon the switching threshold strategy, in which an inverse cotangent function is designed to replace the residual term of the ETM,is proposed to gradually release the controller's dependence on the residual term with increasing time. Furthermore, a tan-type nonlinear mapping technique is applied to tackle the time-varying full-state constraints problem. By the predefined-time stability theory, all signals in the uncertain nonlinear systems exhibit predefined-time stability. Finally, the feasibility of the proposed algorithm is substantiated through two simulation results.

Intense ke V IAP generation by orthogonally polarized multicycle midinfrared two-color laser fields

We theoretically investigate the attosecond pulse generation in an orthogonal multicycle midinfrared two-color laser field. It is demonstrated that multiple continuum-like humps, which consist of about twenty orders of harmonics and an intensity of about one order higher than the adjacent normal harmonics, are generated when longer wavelength driving fields are used. By filtering these humps, intense isolated attosecond pulses（IAPs） are directly generated without any phase compensation. Our proposal provides a simple technique to generate intense IAPs with various central photon energies covering the multi-ke V spectral regime by using multicycle midinfrared driving pulses with high pump energy in the experiment.

Digital holographic shape measurement using Fizeau microscopy

We present a Fizeau interferometer using a microscopic objective as a tool for surface contouring without the need for a numerical lens for reconstruction. The interferometer is associated with a telescope system to feature the object with collimated light. The experiment is conducted on two objects possessing different step heights.The phase maps from the captured off-axis holograms are calculated numerically, which allows us to deduce the contours of the objects. The great advantages of the presented technique are that it can be done in real time and there is no need for numerical lenses for micro-objects reconstruction.