Signaling Scheme Research Articles

Spall length estimation based on strain model and experimental FBG data

Bearings are critical components in most machines that suffer from fatigue damage, and hence need to be monitored. The development of spalls in the bearing races is the prevalent failure mode. In this research, we propose a new diagnostic method for ball bearings monitoring that is based on strain measurement. A standard Fiber Bragg Grating (FBG) sensor has been used for the strain measurement. A physics-based theoretical analysis is used to establish insight and analysis of the strain signals generated by both healthy and faulty bearings. The analysis is based on two complementary models that were integrated into a strain model: a quasi-static Finite element (FE) and a solid bodies dynamic model. The integrated strain model enables simulation of a wide range of spall lengths and describes the behavior of the strain signals as a result of various phenomena. The strain model was validated with measured data. A new signal processing scheme of strain signals for the diagnostics of bearings was established. This scheme enabled the development of a novel automatic algorithm for spall length estimation, which makes it possible, for the first time, to track spall length propagation in bearings outer race, based on strain signals. The algorithm was developed and validated based on seeded fault experiments, wherein different sizes of faults on the outer race at different rotational speeds were examined. The trend of the spall length during a bearing endurance test was generated and verified. The insights from the strain model, combined with the experimental observations, enable generalization of the algorithm and definition of its capabilities and limitations.

Algorithms for Persuasion with Limited Communication

The Bayesian persuasion paradigm of strategic communication models interaction between a privately informed sender and an ignorant but rational receiver. The goal is typically to design a (near-)optimal communication (or signaling) scheme for the sender. It enables the sender to disclose information to the receiver in a way as to incentivize her to take an action that is preferred by the sender. Finding the optimal signaling scheme is known to be computationally difficult in general. This hardness is further exacerbated when the message space is constrained, leading to NP-hardness of approximating the optimal sender utility within any constant factor. In this paper, we show that in several natural and prominent cases the optimization problem is tractable even when the message space is limited. In particular, we study signaling under a symmetry or an independence assumption on the distribution of utility values for the actions. For symmetric distributions, we provide a novel characterization of the optimal signaling scheme. It results in a polynomial-time algorithm to compute an optimal scheme for many compactly represented symmetric distributions. In the independent case, we design a constant-factor approximation algorithm, which stands in marked contrast to the hardness of approximation in the general case.

Outer Bounds for a Joint Communicating Radar (Comm-Radar): The Uplink Case

Limited access to available spectrum motivates new age radio frequency (RF) systems to co-exist and cooperate. In this paper, we consider a joint communication and radar system (labeled Comm-Radar), that is capable of receiving and decoding communication signals while simultaneously enabling radar functionalities. Traditionally, systems that leverage principles of spectrum convergence, deemed each functions to be detrimental to the others. This has led to successive interference cancellations strategies that effectively isolate each of the functionalities. Here, in the context of Comm-Radar processing structure, we show that ambient communication transmissions actually assist in radar estimation. The insight is that communications multipath reflects off radar targets (we denote these comm-target paths) in the environment, and can be processed at the receiver to extract extra information. In this work we characterize the fundamental performance limits of such a joint system.To demonstrate the radar performance gain achievable via the processing of extra comm-target paths, the closed-form Cramér-Rao Bound (CRB) for the estimation of direction, range and velocity of a target is derived, for both the general case, and practical radar and communication signalling schemes. Based on the CRB, joint outer bounds are obtained to characterize the trade off between estimation performance and communication rate. Finally, numerical results verify the advantages of utilizing the target reflections from the communication signal to bolster radar performance.

Reduced-Complexity FFT-Spread Multicarrier Faster-Than-Nyquist Signaling in Frequency-Selective Fading Channel

In this paper, we propose novel reduced-complexity fast Fourier transform (FFT)-spread multicarrier faster-than-Nyquist (MFTN) signaling with power allocation for a frequency-selective fading channel. The information rate of the proposed MFTN signaling is derived by relying on the circulant approximation of the FTN-specific intersymbol interference matrix and noise covariance matrix. This allows us to constitute efficient calculations of precoding and weighting matrices. The power allocation coefficients are optimized such that the approximated information rate is maximized. Our simulation results demonstrate that the proposed scheme with power allocation achieves the bit error ratio (BER) performance close to the conventional eigenvalue-decomposition (EVD)-precoded FTN signaling counterpart that is optimal in terms of an achievable information rate while significantly reducing the computational complexity as low as the order of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathcal {O}(N\log N)$ </tex-math></inline-formula> . While the proposed scheme exhibits a high peak-to-average-power ratio similar to the conventional EVD-precoded counterpart due to the effects of FFT-based precoding, it achieves better BER performance than the conventional open-loop single-carrier FTN signaling scheme and the Nyquist signaling scheme, employing the same root-raised cosine shaping filter. It is also confirmed that the proposed MFTN signaling scheme does not suffer from any significant bandwidth broadening.

Simulation optimisation of displaced left-turn intersection layout with multi-objectives

Displaced left-turn (DLT) intersections, which effectively solve the conflict between left-turn and opposing-through traffic, are currently the most efficient innovative intersection design. However, the special layout of DLT will inevitably cause high difficulty in channelisation design. For full use of the potential traffic capacity of DLT intersection, a multi-objective optimisation model for intersection with DLT layout (MOOM-DLTL) is built based on integrated simulation and mathematical programming (ISMP) framework. In this model, the signal scheme is regarded as the accompanying strategy of DLT layout optimisation to describe the interaction between layout and signal control. In addition, the multi-objective particle swarm optimisation based on shift-based density estimation (MOPSO+SDE) algorithm is developed to obtain the Pareto front of the proposed model. A series of experimental results show that the proposed optimisation method is successful in improving the traffic efficiency of DLT intersection.

Sub-Nyquist Sampling of Multiple Exponentially Damped Sinusoids With Feedback Structure

Multiple exponentially damped sinusoids (MEDS) signals have been widely applied to the fields of speech analysis and nuclear magnetic resonance imaging systems. Although sub-Nyquist sampling schemes were proposed in previous works, either the image frequency aliasing was not resolved, or the parameters measuring process required a large number of samples. In this paper, a feedback based sub-Nyquist sampling and parameters measurement scheme for MEDS signals is proposed to address these problems. Since sub-Nyquist sampling would lead to frequencies ambiguity, an additional sampling is designed to determine the true frequencies. Moreover, image frequency aliasing would occur when the difference between two true frequencies is an integer multiple the sampling rate. To prevent image frequency aliasing, a feedback sampling strategy and a dealiasing algorithm are proposed. The proposed scheme enables sub-Nyquist sampling and parameters measurement of MEDS signals with K frequency components, by using only 4K samples. We also propose a hardware prototype to implement the proposed system. Simulation and hardware experiment results have shown that the frequency estimation accuracy of the proposed method has been improved on average by about 11.65 dB than previous works under noise environment, and the statistical variance experiments have shown that it has better stability.

A Classification Scheme for ECG Signals Based on Bidirectional LSTM Model

The application of ECG to diagnose cardiovascular diseases is a common method in clinical medicine, so the use of deep learning tools to achieve automatic analysis and classification of ECG has been a research direction for a wide range of researchers. This paper proposes a classification model for ECG signals based on a bidirectional LSTM model which is trained and tested using the dataset used for the PhysioNet 2017 computational cardiology challenge. The data are normalized and then processed by feature extraction. After passing a bidirectional LSTM layer, a fully connected layer, a softmax layer, and a classification layer in the model, and finally achieve the binary classification of normal signals and atrial fibrillation signals. In this process, the feature of bidirectional LSTM that can integrate contextual information is fully utilized. The experiments show that the classification accuracy of the model reaches 94.1%, demonstrating a good classification result.

A Quantitative Analysis of Compromising Emanation From TMDS Interface and Possibility of Sensitive Information Leakage

This paper investigates the electromagnetic interference characteristics of the transition-minimized differential signaling (TMDS) scheme, a well-known technology for rapid serial data transmission, from a radio communication perspective. Such scrutiny regarding the leaking phenomenon inspires a pseudo model of the compromising signal model, which can simultaneously consider behavioral features of the software-defined radio with a simple RF front-end measuring the leakage. In this work, a conceptual explanation with mathematical formulations in implementing the pseudo model has been presented. Subsequently, by merging the model with various extra noises being in nature, the model can be utilized to facilitate and quantify the possibility of information extraction from the defected electromagnetic signatures. Furthermore, it is interesting to note that there are asynchronous problems due to inevitable timing errors in video display devices, even with a sophisticated acquisition system, turning out to be fatal for the frame-averaging scheme conducted before the signal demodulation. In view of these challenges, we have formulated a synchronizing scheme and verified validity by utilizing the pseudo model with the extra noise to take into account the asynchronous problem. Moreover, the structural similarity (SSIM), a function of the signal-to-noise ratio, can provide the number of frames for the frame-averaging process and eventually give the minimum acquisition time to earn meaningful information from the compromising emanation. Finally, after the appropriate post-processing, the extracted information from the actual measurements is compared with the reconstruction from the pseudo-model results revealing excellent agreements.

Biomedical Multimedia Encryption by Fractional-Order Meixner Polynomials Map and Quaternion Fractional-Order Meixner Moments

Chaotic systems are widely used in signal and image encryption schemes. Therefore, the design of new chaotic systems is always useful for improving the performance of encryption schemes in terms of security. In this work, we first demonstrate the chaotic behavior of fractional order Meixner polynomials (FrMPs) for introducing a new two-dimensional (2D) chaotic system called FrMPs map. This system is very sensitive to any variation by 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-15</sup> of its control parameters (μ and β).Next, we use FrMPs to introduce a new type of orthogonal transforms called quaternion fractional order Meixner moments (QFrMMs). The latter generalize the existing fractional order Meixner moments. To demonstrate the relevance of the proposed FrMPs map and QFrMMs in the field of signal and image processing, they are applied in the development of a new encryption scheme. The main advantage of this scheme is its applicability to the encryption of different types of biomedical data such as multi-biomedical signals, multiple grayscale medical images, color medical image, and grayscale medical image. Several simulation analysis (visual, histogram, runtime, correlation, robustness, etc.) are conducted to verify the efficiency of the proposed scheme. Simulation and comparison results confirm that our encryption method is effective in terms of high security level, high quality of the decrypted information, strong resistance to different types of attacks, etc. These findings support the suitability of the proposed scheme for the secure exchange of biomedical multimedia via a public communication channel.

Distributed Load Control Using Reliable Low-Data-Rate Power Line Communication

Many demand-response schemes fail because they inconvenience consumers or add unnecessary costs [1], [2]. When participating in a typical demand-response scheme, a consumer may be subjected to invasive control systems, communication systems, or data collection. These demand-response schemes can quickly lose their novelty and may annoy customers by curtailing availability of their appliances, such as electric water heaters or air conditioners [2]. This paper demonstrates a self-organizing demand response scheme that uses power lines as a natural, “free” infrastructure for communication. The approach can shave peak demand substantially with no inconvenience to or attention from the user. Tailored signaling schemes and a custom application of low-data-rate power line communication (PLC) enable loads to reliably self-organize their demand. Field experiments with thermostatically-controlled loads in an actively occupied, 24-floor apartment building demonstrate the advantages of the low-data-rate PLC scheme for energy control.

Joint Radar and Communications for Frequency-Hopped MIMO Systems

Contention in the frequency spectrum has seen the emergence of Dual-Function Radar Communications (DFRC) systems, enabling frequency-hopped (FH) multiple-input-multiple-output (MIMO) waveforms to carry communication symbols. While a variety of novel signaling strategies have been developed to facilitate the communication function, their implementation in slow-time results in the achievable data rate being limited by the radar pulse repetition interval. We develop a generalized framework for performing information embedding in DFRC systems by exploiting the fast-time structure of the transmitted radar waveform. By defining a unified formulation, we show that a variety of existing signaling strategies can be accommodated, including FH index modulation, FH permutation, quadrature amplitude modulation (QAM), M-arry PSK (MPSK) modulation and/or frequency carrier index modulation. In addition, we use this framework to propose hybrid modulation strategies constructed using combinations of the aforementioned schemes to produce significant improvements in the achievable data rate over the individual signaling schemes. Simulation results demonstrate that the hybrid schemes can deliver significantly higher bit rates with only small increases in the required <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$E_b/N_0$</tex-math></inline-formula> . They also show that, in terms of the impact on the radar operation, the frequency hopping code selection has the highest range sidelobes whereas the PSK schemes suffer from significant spectral leakage. Finally, we also give a discussion of the issues and open problems that remain unaddressed.

Backward Data Transfer From Deeply Implanted Device Employing Ultrasonic Load Amplitude-Phase Shift Keying.

Ultrasonic transcutaneous energy transfer (UTET) is used to wirelessly energize low-power miniature implanted devices. Whenever backward data transfer from the implant is of interest, load modulation may be utilized. With load modulation, data is sent backward by imposing ultrasonic reflections from the implant-tissue contact surface. This may be achieved by imposing unmatched electrical load over the implanted transducer electrical terminals. In order to sustain sufficient ultrasonic average power harvesting also during backward data transfer, only a small portion of the impinging ultrasonic energy is allowed to reflect backward. Previous work focused primarily on load modulation via ON- OFF keying (OOK). Herein, it is further shown that phase shift keying can be realized by exploiting the phase characteristics of a matched transducer around its vibration resonance. Load amplitude shift keying (ASK) properly combined with load phase shift keying (LPSK) may be applied, for introducing energy-efficient, high-order signaling schemes, thus improving utilization of the ultrasonic channel. LPSK is realized by momentary imposing reactive loads across the implanted transducer electrical terminals, according to the bit stream of the data to be sent. In this work, LPSK with various constellations and coding are demonstrated, exploiting the acoustic impedance dependency of the implanted piezoelectric resonator on its electrical loading. To support the theoretical notion, a backward data transfer using two-state phase modulation at a bit rate of 20 kbit/s over an ultrasonic carrier frequency of 250 kHz is demonstrated, using finite-element simulation. In the simulation, an implanted transducer was constructed of a 4-mm-diameter hard lead-zirconate-titanate (PZT) disk (PZT8, unloaded mechanical quality property Qm of 1000). The PZT resonator was acoustically matched to the tissue impedance, using a layer of 2.72-mm epoxy filled glue and a 2-mm-thick layer of polyethylene.

DFT Spread-Optical Pulse Amplitude Modulation for Visible Light Communication Systems

DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) has been proposed in visible light communication (VLC) to overcome the limited modulation bandwidth of light emitting diode (LED). Due to the implementation of the inverse fast Fourier transform at the DCO-OFDM transmitter, DCO-OFDM suffers from its high peak-to-average power ratio (PAPR), which restricts its use in some VLC applications, especially where the optical power efficiency is a crucial requirement. That is because the LEDs used in VLC systems have a limited optical power-current linear range. To this end, a novel discrete Fourier transform spread-optical pulse amplitude modulation (DFTS-OPAM) signal scheme based on the single carrier-interleaved frequency division multiple access (SC-IFDMA) signal is introduced in this paper to address the high PAPR issue of OFDM. DFTS-OPAM is achieved by considering a PAM as an SC-IFDMA data symbol and duplicate the output vector of the fast Fourier transform at the SC-IFDMA transmitter side. Simulation results show that the PAPR of the proposed scheme is 7 dB lower than that of DCO-OFDM. Furthermore, this significant PAPR improvement is experimentally investigated where the practical results show that the proposed scheme can provide more 2.5 dB reduction in the average transmitted power requirement compared to DCO-OFDM and can subsequently increase the maximum achieved distance between the transmitter and the receiver up to 44%.

Improvement and evaluation of ATWS Protective Signal and mitigation system for ACPR1000 nuclear power plant

At the event of Loss of Normal Feed Water-An Anticipated Transient without Scram (LOFW-ATWS) in ACPR1000 unit, there exists the primary overpressure risk probability when the regulation function of temperature regulation (R) rods and power regulation (G) rods cannot work timely or lost. In order to reduce primary pressure and avoid the overpressure risk in this transient process, this paper proposes the improvement scheme of ATWS protective signal and mitigation measure which adds shutting-down action of coolant pumps, and then adopts THEMIS program to analyze ATWS transient to verify this scheme. The verification results indicate that the improvement scheme can effectively reduce the peak value of primary pressure and eliminate the overpressure risk in LOFW-ATWS event. This improvement scheme has been adopted in the design of Yang Jiang Nuclear Power Plant (NPP) 5&6 units in China.

Analysis of earthquakes recordings of tidal gravimeters in the period range of 10-1000 s

The physical properties of tidal gravimetric instruments allow recording, not only tidal effects, but also waves generated by earthquakes. Three gravimetric stations with determined transfer functions and co-located seismic stations from the observatories in Western and Central Europe were selected for analysis. The observatories are equipped with almost all types of sensors available on the market, which allow for thorough analysis of earthquake recordings in the period range of 10–1000 s. In total, over 10,000 traces of worldwide earthquakes were investigated. The saturation levels of gravimeters as well as a correlation between the gravimetric and seismometric signals of an earthquake were carefully analysed. A simple processing scheme of gravimetric signal of earthquakes was adopted thanks to the probabilistic power spectral density analysis of continuous recordings. The detail analysis of transfer function of gravimeters allowed to define a period range when a sensitivity coefficient (calibration factor) and a time lag value only can be used to properly describe the properties of instruments. What’s more, it has been shown based on the calculated group-velocity dispersion curves of fundamental mode of Rayleigh waves, that the Earth’s mantle structure can be determined for greater depths from the recording of tidal gravimeters than from typical broad-band seismometers.

L-Type Calcium Channels Contribute to Ethanol-Induced Aberrant Tangential Migration of Primordial Cortical GABAergic Interneurons in the Embryonic Medial Prefrontal Cortex.

Exposure of the fetus to alcohol (ethanol) via maternal consumption during pregnancy can result in fetal alcohol spectrum disorders (FASD), hallmarked by long-term physical, behavioral, and intellectual abnormalities. In our preclinical mouse model of FASD, prenatal ethanol exposure disrupts tangential migration of corticopetal GABAergic interneurons (GINs) in the embryonic medial prefrontal cortex (mPFC). We postulated that ethanol perturbed the normal pattern of tangential migration via enhancing GABAA receptor-mediated membrane depolarization that prevails during embryonic development in GABAergic cortical interneurons. However, beyond this, our understanding of the underlying mechanisms is incomplete. Here, we tested the hypothesis that the ethanol-enhanced depolarization triggers downstream an increase in high-voltage-activated nifedipine-sensitive L-type calcium channel (LTCC) activity and provide evidence implicating calcium dynamics in the signaling scheme underlying the migration of embryonic GINs and its aberrance. Tangentially migrating Nkx2.1+ GINs expressed immunoreactivity to Cav1.2, the canonical neuronal isoform of the L-type calcium channel. Prenatal ethanol exposure did not alter its protein expression profile in the embryonic mPFC. However, exposing ethanol concomitantly with the LTCC blocker nifedipine prevented the ethanol-induced aberrant migration both in vitro and in vivo. In addition, whole-cell patch clamp recording of LTCCs in GINs migrating in embryonic mPFC slices revealed that acutely applied ethanol potentiated LTCC activity in migrating GINs. Based on evidence reported in the present study, we conclude that calcium is an important intracellular intermediary downstream of GABAA receptor-mediated depolarization in the mechanistic scheme of an ethanol-induced aberrant tangential migration of embryonic GABAergic cortical interneurons.

A Novel Signal Design and Performance Analysis in NavCom Based on LEO Constellation.

The mega-launch of low Earth orbit satellites (LEOs) represents a critical opportunity to integrate navigation and communication (NavCom), but first, challenges related to signal design must be overcome. This article proposes a novel signal scheme named CE-OFDM-PM. Via research on the in-band or adjacent band, it was found that the proposed signal scheme was suitable for S-band and had a wide normalized power spectrum density (PSD), high peak-to-side lobe ratio (PSR), and multiple peaks in autocorrelation. In an analysis of the simulation performance evaluation in navigation and communication, it is found that the proposed signal scheme has the potential for high accuracy, a code tracking accuracy of up to 0.85 m, a small mutual influence between the proposed signal scheme and other schemes, excellent anti-interference properties, and a better performance at both short and long distances in terms of its anti-multipath capability. Furthermore, the proposed signal scheme shows the ability to communicate between satellites and the ground and is outstanding in terms of its bit error rate (BER), CNR, and energy per bit to noise power spectral density ratio (Eb/N0). From the technical, theoretical, and application perspectives, our proposed signal scheme has potential as an alternative scheme in future BDS, PNTs, and even 5G/B5G.

Numerical analysis of UFMC and FBMC in wavelength conversion for radio over fiber systems using semiconductor optical amplifier

The 5G networks promise to use advanced access techniques and modulation formats to achieve new requirements of the huge number of users such as higher data, high speed, and low latency. Millimeter-wave (MMW) signal and new modulation schemes such as universal filtered multicarrier (UFMC) and filtered bank multicarrier (FBMC) are playing a fundamental role to accomplish these requirements. UFMC and FBMC are classified under multicarrier modulation formats which are considered as a suitable modulation scheme in 5G and replacing a well-known modulation format of filtered orthogonal frequency division multiplexing (OFDM) which was used in 4G. This interest in using UFMC and FBMC in 5G wireless systems is the reduction of out-of-band (OOB) spectrum in UFMC and reduction of sidelobe suppression in FBMC. The contribution of this paper is to propose a model of wavelength conversion using a semiconductor optical amplifier (SOA) for both schemes UFMC and FBMC- off-set quadrature amplitude (OQAM). In addition, we analyze and compare their performance in terms of bit error rate (BER) and error vector magnitude (EVM) for a wavelength conversion application. Finally, we investigate the main disadvantage of OFDM which is the high Peak to Average Power Ratio (PAPR) for both schemes, and compare between them. Photonic switching of a 4 Gbps 16-QAM UFMC and FBMC-OQAM signal centered at 50 GHz is performed. The optical single-sideband (OSSB) signal is generated with 18.85 dB of sideband suppression ratio (SSR). The results show that the best values of BER and EVM can be obtained when the injection current (IC) is 0.7–0.9A. For converted signal using FBMC-OQAM, it has power penalty ∼ 2.5 dB at BER threshold 1 × 10-3and has also ∼ 2 dB power penalty compared to the UFMC scheme at EVM threshold 5.6%. In addition, the wavelength switching system with FBMC and UFMC modulation schemes achieves the same PAPR.

Direct Detection Under Tukey Signalling

A new direct-detection-compatible signalling scheme is proposed for fiber-optic communication over short distances. Controlled inter-symbol interference is exploited to extract phase information, thereby achieving spectral efficiencies about one bit less, per second per hertz, of those of a coherent detector.

An Efficient Parallel Block Compressive Sensing Scheme for Medical Signals and Image Compression

Compressive Sensing or Compressed sensing (CS) is a latest technique used for compression of medical signals and medical images which benefits both the speed and accuracy. The performance of CS based compression is mostly dependent on decoding methods rather than the CS encoding methods used in practice. It has been found in literature that CS encoding algorithms have got least importance than decoding algorithms. In this paper an efficient CS encoding scheme based on modified parallel block processing has been suggested for biomedical signal and image compression. The input signals and images are acquired and preprocessed with suitable filtering techniques and then the same have been divided into number of cells and blocks. Each block is then processed in parallel to enable faster computation. Three performance indices, i.e., the peak signal to noise ratio (PSNR), reconstruction time (RT) and structural similarity index (SSIM) have been analyzed with respect to the compression ratio. A comparative study has been carried out between the standard CS based compression and the suggested technique. The results showed that proposed algorithm provides better performance than standard CS based compression. More specifically, the parallel block CS reported the best results than standard CS with respect to less reconstruction time and satisfactory PSNR and SSIM. The suggested technique offers SSIM improvement approximately by 8% and reduction in RT by 99% than the standard CS based compression for CT scan image compression. In case of brain signal compression, the suggested technique offers SSIM improvement approximately by 25%, PSNR improvement by around 2% and reduction in RT by 75% than the standard CS.