Aging state detection of viscoelastic sandwich structure using redundant second generation wavelet packet transform and fuzzy support vector data description

Viscoelastic sandwich structure plays an important role in mechanical equipment, nevertheless viscoelastic material inevitably suffers from gradual aging. For guaranteeing the operation safety of mechanical equipment, it is urgent to perform the aging state detection of viscoelastic sandwich structure with vibration response signal analysis. However, the structural vibration response signal is non-stationary and its variation caused by the structural aging state change is very puny, and the abnormal state samples is lacking. The vibration-based structural aging state detection has become a challenging task. Therefore, a novel method based on redundant second generation wavelet packet transform (RSGWPT) and fuzzy support vector data description (FSVDD) is proposed for this task. For extracting sensitive aging feature information, RSGWPT is introduced to process the structural vibration response signal, and multiple energy features are extracted from the frequency-band signals to reflect structural aging state change. For accurate and automatic aging state identification, by fusing fuzzy theory, FSVDD only uses the normal state samples for training and can identify the abnormal severity degrees is developed to identify the structural aging states. The proposed method is applied on a viscoelastic sandwich structure to validate its effectiveness, and different structural aging states are created through the accelerated aging of viscoelastic material. The analysis results show the outstanding performance of the proposed method.

Multipoint Monitoring of Amplitude, Frequency, And Phase of Vibrations Using Concatenated Modal Interferometers

Concatenated modal interferometers-based multipoint sensing system for detection of amplitude, frequency, and phase of mechanical vibrations is proposed and demonstrated. The sensor probes are fabricated using identical photonic crystal fiber (PCF) sections and integrated along a single fiber channel to act as a compact and efficient sensing system. Each identical probe acts as a modal interferometer to generate a stable interference spectrum over the source spectrum. In presence of external dynamic field about each probe, the probes respond independently, producing a resultant signal that is a superposition of each interferometer response signal. By analysing the resultant signals using computational techniques, the vibration parameters applied to each interferometer are realized. The sensing system has an operation range of 1 Hz-1 kHz with a sensitivity of 51.5 pm/V. Such a sensing system would find wide applications at industrial, infrastructural, and medical fronts for monitoring various unsteady physical phenomena.

Characterisation of signal-induced noise in Hamamatsu R11265 Multianode Photomultiplier Tubes

Signal-induced noise is observed in Hamamatsu R11265 Multianode Photomultiplier Tubes, manifesting up to several microseconds after the single photoelectron response signal and localised in specific anodes. The mean number of noise pulses varies between devices, and shows significant dependence on the applied high-voltage. The characterisation of this noise and the mitigation strategies to perform optimal single-photon counting at 40 MHz, as required by the LHCb Ring-Imaging Cherenkov detectors, are reported.

A rectangular radio pulse propagation in a selectively absorbing medium

A pulse with rectangular envelope propagation, in which carrier frequency is close to the medium spectral absorption line’s one frequency, is considered. It is shown that when the signal carrier frequency is shifted relative to the spectral line centre, the primary interference and the response signal can lead to the total signal significant oscillations over time.

Research on Load Disturbance Based Variable Speed PID Control and a Novel Denoising Method Based Effect Evaluation of HST for Agricultural Machinery

This paper aims to realize and improve the constant speed control performance of tractors with HST (Hydrostatic Transmission) variable speed units. To achieve this, based on the HST test bench of the tractor, we perform a verification test of the adjustable speed characteristics, a denoising filter test of the response signal, a test on the influence of the load disturbance on the adjustable speed characteristics and a PID-based constant speed performance detection test. The results of the verification test of the adjustable speed characteristics show that the theoretical value and actual value of the adjustable speed transmission characteristics of the HST used are essentially consistent with each other. The results of the test of the load disturbance’s influence on the adjustable speed characteristics show that the increase in load torque inhibits the HST output response. Therefore, the paper proposes and designs a PID-based closed-loop constant speed control system. The paper uses a step response test and a load disturbance test to research the control result of the constant speed system. Collecting and analyzing all test results, we find that the constant speed control based on PID has a very good result. The average error between the average HST output speed and the target speed set was 0.37%, and the average standard deviation of output speed was 1.18 rpm. In addition, the paper proposes a denoising method combing the empirical mode decomposition method and the Gaussian distribution determination. The method shows that the first two orders of the components of the HST response signal should be removed as noise. The paper uses the denoised signal and the partial least squares method to analyze the influencing factors of the constant speed control result. The analysis results show that the rate of change of load torque has the biggest influence on the stability of HST output speed, followed by the target value.

ProMetheusDB: an in-depth analysis of the high-quality human methyl-proteome

Protein Arginine (R) methylation is a post-translational modification involved in various biological processes, such as RNA splicing, DNA repair, immune response, signal transduction, and tumour development. Although several advancements were made in the study of this modification by mass spectrometry, researchers still face the problem of a high false discovery rate. We present a dataset of high-quality methylations obtained from several different heavy methyl SILAC (hmSILAC) experiments analysed with a machine learning-based tool doublets and show that this model allows for improved high-confidence identification of real methyl-peptides. Overall, our results are consistent with the notion that protein R methylation modulates protein:RNA interactions and suggest a role in rewiring protein:protein interactions, for which we provide experimental evidence for a representative case (i.e. NONO:PSPC1). Upon intersecting our R-methyl-sites dataset with a phosphosites dataset, we observed that R methylation correlates differently with S/T-Y phosphorylation in response to various stimuli. Finally, we explored the application of hmSILAC to identify unconventional methylated residues and successfully identified novel histone methylation marks on Serine 28 and Threonine 32 of H3.

Nanomaterial-Based Dual-Emission Ratiometric Fluorescent Sensors for Biosensing and Cell Imaging

Owing to the unique optophysical properties of nanomaterials and their self-calibration characteristics, nanomaterial-based (e.g., polymer dots (Pdots) quantum dots (QDs), silicon nanorods (SiNRs), and gold nanoparticle (AuNPs), etc.) ratiometric fluorescent sensors play an essential role in numerous biosensing and cell imaging applications. The dual-emission ratiometric fluorescence technique has the function of effective internal referencing, thereby avoiding the influence of various analyte-independent confounding factors. The sensitivity and precision of the detection can therefore be greatly improved. In this review, the recent progress in nanomaterial-based dual-emission ratiometric fluorescent biosensors is systematically summarized. First, we introduce two general design approaches for dual-emission ratiometric fluorescent sensors, involving ratiometric fluorescence with changes of one response signal and two reversible signals. Then, some recent typical examples of nanomaterial-based dual-emission ratiometric fluorescent biosensors are illustrated in detail. Finally, probable challenges and future outlooks for dual-emission ratiometric fluorescent nanosensors for biosensing and cell imaging are rationally discussed.

Determination of the working temperature of the MOS sensors used for the detection of ethanol and methanol

In this work, some peruvian red wines were analyzed using gas chromatography coupled to mass spectrometry (GC-MS) and it was determined that ethanol was the major volatile component present in the aroma (12 % in volume). followed by methanol (2-3 % in volume). Some MOS sensors based on SnO2 doped with Pd and Pt were prepared by precipitation with metallic charges from 0.1 to 0.5% and were tested with the same Peruvian wines. The stability and reproducibility of the sensing signal was analyzed at different working temperatures (200, 220, 240, 260 and 280 °C). The best working temperature at which the highest intensity of the response signal of the sensors was obtained at 260 ⁰C. In most of the cases studied, the sensing signal of the sensors was in general repetitive and stable, maintaining its amplitude and shape during long periods of the analysis. However, at the temperature of 280 ° C the signal loses intensity and in contact with methanol the signal is distorted.

Vibration stability analysis of cantilever structure based on symbolic regression algorithm and modal analysis method

The vibration stability of cantilever mechanism under high-speed rotation directly affects the positioning accuracy. Modal analysis method is usually used to study the vibration stability. However, the traditional experimental modal analysis (EMA) method needs to measure the impulse excitation, while the operational modal analysis (OMA) method needs to satisfy the assumption of white noise. Therefore, the existing modal analysis methods cannot be applied to the study of vibration stability of high-frequency cantilever mechanism. In this paper, the symbolic regression (SR) algorithm is combined with the EMA method, and the robustness analysis and feasibility verification are carried out under the condition of adding noise. The validation of the new method is divided into two parts. In the first part, a three degree of freedom (DOF) linear model is constructed, and the modal parameters identified by SR method and state space method are compared. In the second part, the method is applied to identify the modal parameters of stepped bar. The results are compared with the results of LMS (Siemens’ Testlab). Based on the time-domain response signal only, the modal parameters are extracted by SR, and the main vibration frequency is extracted from the response signal. The system simulation and experimental results show the method provides a possibility to analyze the vibration stability of cantilever structure.

Research on Output Signal Controlling of an Asymmetric Hydraulic Cylinder Based on a Flexible Connection

In industrial production, the structures of hydraulic servo system-connecting device-load systems are often simplified as rigid connections for the ease of calculation. However, this simplification is problematic when applied to flexible connections in hydraulic systems, which generally have multivariable and strong couplings; these characteristics affect the control accuracy of the hydraulic servo system and lead to serious distortion of the output waveform, which cannot be ignored. These problems cause greater lag and attenuation of the actual signal than those of the expected signal, leading to lower credibility. Therefore, it is important to study the waveform distortion caused by flexible connections. In this paper, according to the characteristics of a flexible connection, a corresponding mathematical model is established, and an adaptive controller, whose structure is simple and calculation cost is low, is used to adjust the amplitude and phase of the response signal and improve the accuracy of the system response. Treating the change in the response signal as the error value, the algorithm weights are adjusted until the error value is stable. Then, a more accurate output signal is obtained. Finally, the validity and practicability of the adaptive controller are verified by simulation experiments.