Analysis Of Signal Characteristics Research Articles

Study on Feeding Activity of Litopenaeus Vannamei Based on Passive Acoustic Detection

Litopenaeus vannamei, as the main target of shrimp farming in China, has a great market prospect and high economic value. However, domestic Litopenaeus vannamei farming and feeding efficiency are low, mainly through the use of hand tools by farmers to complete the feed throwing work, and the feed cost is high. Therefore, in view of the high density and low visibility of culture ponds in Litopenaeus vannamei aquaculture industry, it is impossible to judge the quantity and time of feed feeding by visual way. In this study, based on the analysis of acoustic feeding signal characteristics of Litopenaeus vannamei, accurate and intelligent control of feed amount is proposed, so as to reduce the breeding cost and obtain environmental benefits. This study designed a system for collecting and analyzing the acoustic signals of the feeding motion of Litopenaeus vannamei. Based on passive acoustic technology, the motion acoustic signal of Litopenaeus vannamei is extracted when starving. Through time domain and frequency domain research, the characteristic parameters of the motion acoustic signal of the specific body type of Litopenaeus vannamei are determined. The signal duration range is 8-10ms, and the average range of the resonance band is 2-10KHz. Furthermore, the dual-threshold method is further used to detect the effective range of the feeding signals, and then the number of acoustic signals is obtained, and the corresponding magnitude relationship between the characteristic parameters and the starvation degree of Litopenaeus vannamei is established, which can be used as a basis for judging intelligent feeding on demand. The research provides theoretical support for the feasibility of studying the feeding patterns of Litopenaeus vannamei through underwater passive acoustic detection.

Signal Characteristics Analysis and Intra-Pulse Motion Compensation for FMCW CSAR

The combination of frequency modulation continuous wave (FMCW) technology and circular synthetic aperture radar (CSAR) would pave the way for the development of the microminiature unmanned aerial vehicle (UAV) earth observation application. Regarding the FMCW CSAR imaging process, the stop-and-go approximation is no longer effective due to the longer pulse duration. In addition, the signal characteristics of FMCW CSAR with higher frequency band and higher resolution need to be further studied. Aiming at millimeter-wave FMCW CSAR imaging, the signal models of FMCW CSAR in the time domain and wavenumber domain are first derived in this work. Then, the signal characteristics including the two-dimensional (2-D) wavenumber spectrum, the spectrum support region, the point spread function, and the resolution are analyzed. Moreover, the effects of intra-pulse movement are analyzed, including the range offset error, the main lobe broadening, and the additional phase error in the range dimension, as well as the extra first-order and second-order phase errors in the 2-D wavenumber domain. Based on the intra-pulse motion analysis, two criterions are provided to determine whether the intra-pulse movement of FMCW CSAR is negligible. An improved back projection (BP) algorithm compensating the intra-pulse motion in the range domain and another algorithm combining the traditional BP and compensation the intra-pulse motion in the wavenumber domain are proposed. Simulation results verify the correctness of the FMCW CSAR signal characteristics analysis and the effectiveness of the intra-pulse movement compensation methods.

Mental workload characteristics of manipulator teleoperators with different spatial cognitive abilities

The main research on manipulator teleoperation includes robust of high-degree of freedom manipulators, sensor measurement accuracy, time delay, and mechanical structure design. Increased mental capacity requirements for complex assignments result in an increased mental workload. Spatial cognitive ability was considered to be the key factor affecting teleoperation performance. To accomplish this, we had 50 participants performed teleoperation while recorded their electroencephalogram. Electroencephalogram data of each task were divided into two periods, which correspond to the observation and large-scale transfer stages of teleoperation, respectively (period 1) and adjust the attitude of the manipulator to approach and align with the target stage (period 2). Brain topographic maps of period 1 (period 1 wavelet packet energy minus resting state wavelet packet energy) and period 2 (period 2 wavelet packet energy minus resting state wavelet packet energy) show that the frontal, central, and occipital regions are the main working areas of low spatial cognitive operators in period 1, while the frontal, central, and occipital regions are the main working areas of high spatial cognitive operators in period 1. The main changes in period 2 were frontal, central, parietal, and occipital regions. This study has implication for the analysis of electroencephalogram signal characteristics of mental workload in different populations to improve operators’ well-being and safety at teleoperation work.

Lightning severity classification technique using Very Low Frequency signal feature extraction

High intensity lightning strike can lead to Very Low Frequency (VLF) signal reception. The lack of VLF signal feature characterisation creates the need for commercial lightning dataset subscription, so as to determine the causative lightning strike. This paper presents a signal feature analysis of VLF signal for high intensity lightning severity classification purpose. As such, the analysis was comprised of dual stages, namely feature extraction and feature classification, for two-class recognition. In the feature extraction stage, Discrete Wavelet Transform was implemented to decompose the VLF signal into four frequency bands. In each frequency band, five-signal parameter analysis was executed to yield twenty signal features. Next, the classification stage was executed to determine the best signal feature combination and the most dominant signal feature that generated the highest classification accuracy within the five classifiers. The simulation revealed that the most optimum signal feature combination was achieved via Boosted Trees classifier with classification accuracies of 70% and 50% for training and test datasets, respectively. Class prediction in the skewed test dataset appeared consistent with the test data classification accuracy. The Zero Crossing Rate between 30 and 60 kHz emerged as the most dominant signal feature due to its impact on all classifiers' best signal feature arrangement. The proposed recognition model enables the detection of high intensity lightning classes through the use of VLF signal features.

Investigation of the impressed current cathodic protection method for the cable parallel wires in the rainwater electrolyte based on acoustic emission method

The corrosion durability of bridge cables in operation is prominent. This study proposes an active protection method to apply impressed current cathodic protection (ICCP) to bridge cable parallel wires. The weight loss method, scanning electron microscopy, electrochemical test, and acoustic emission (AE) signal characteristic analysis were used to study the test method for electrochemical corrosion protection of cable parallel wires using rainwater conduction. Results show that cable wires are corroded on the surface and inside, whereas the cable wires with ICCP show different changes. The cable wires are effectively protected in the environment where a sodium chloride solution is used to simulate rainfall. In the AE test of the cable wires after corrosion using a signal generator, the main frequency of the AE signal gradually increases with the increase in corrosion degree. The high corrosion degree of the cable wires induces dispersion. The characteristics of AE signal can reflect the corrosion degree of the cable wires, and ICCP can decrease the corrosion rate of the cable wires.

The Ultra-Low-k Dielectric Materials for Performance Improvement in Coupled Multilayer Graphene Nanoribbon Interconnects

The ultra-low-k dielectric material replacing the conventional SiO2 dielectric medium in coupled multilayer graphene nanoribbon (MLGNR) interconnects is presented. An equivalent distributed transmission line model of coupled MLGNR interconnects is established to derive the analytical expressions of crosstalk delay, transfer gain, and noise output for 7.5 nm technology node at global level, which take the in-phase and out-of-phase crosstalk into account. The results show that by replacing the SiO2 dielectric mediums with the nanoglass, the maximum reduction of delay time and peak noise voltage are 25.202 ns and 0.102 V for an interconnect length of 3000 µm, respectively. It is demonstrated that the ultra-low-k dielectric materials can significantly reduce delay time and crosstalk noise and increase transfer gain compared with the conventional SiO2 dielectric medium. Moreover, it is found that the coupled MLGNR interconnect under out-of-phase mode has a larger crosstalk delay and a lesser transfer gain than that under in-phase mode, and the peak noise voltage increases with the increase of the coupled MLGNR interconnect length. The results presented in this paper would be useful to aid in the enhancement of performance of on-chip interconnects and provide guidelines for signal characteristic analysis of MLGNR interconnects.

Research of Machine Learning Algorithm for Broadcasting Spectrum Signal Processing

FM broadcasting is mainly used to transmit sound and other signals in the form of wireless transmission. This thesis is based on a project for a radio department, and mainly focuses on the broadcasting frequency band, uses radio monitoring equipment to scan the spectrum signal of the broadcasting frequency band, and performs the data preprocessing, signal feature extraction and classification processing of the radio frequency spectrum signal on the extracted spectrum signal, so as to extract abnormal signals such as pseudo base stations, black radio, cheats in exams, etc. Firstly, relevant pre-processing is performed on the spectrum information of the broadcast frequency band. Through the improved K-Means algorithm, the original sample data including the glitch signal is eliminated, and the original signal is processed through the wavelet analysis of the spectrum signal. The original signal was decomposed by wavelet and wavelet reconstruction, so as to achieve the purpose of denoising the original signal. Secondly, based on the analysis of signal characteristics and the comparison of a large number of spectrum signals, a method for extracting individual features of spectrum signals is summarized. Finally, the grey relational degree cluster Analysis is used to extract the features of the spectrum signal, which provides a certain basis for the subsequent classification algorithm.

Phase analysis‐based stationary clutter suppression under iron‐structures for automotive FMCW radar

In this study, to reduce the performance degradation due to iron-clutter, the authors propose a suppression method for stationary clutter under iron-structures for an automotive radar using a frequency-modulation continuous-wave (FMCW) radar. The presence of a large number of iron-structures such as iron-bridges, soundproof walls, and iron-tunnels creates a harsh environment that deteriorates the associated radar detection performance owing to clutter. To mitigate the adverse effects of clutter, they propose a clutter suppression scheme using up- and down-chirp signals based on an analysis of signal characteristics. In particular, it is shown that the stationary clutters can be suppressed by making that the phases of the up-chirp and down-chirp are similar. To experimentally verify the proposed method, 77 GHz FMCW radar data for adaptive cruise control was acquired along a road on which several iron-structures were located. The experimental results show that using the proposed clutter suppression scheme, the frequency of the moving target was detected well using the proposed clutter suppression scheme in an iron-clutter-rich environment. Through the application of the proposed clutter suppression scheme, stable target detection performance of the radar can be obtained.

Monitoring and early warning method for a rockfall along railways based on vibration signal characteristics

Rockfall disasters occur frequently in mountainous areas of western China, and the rockfall disasters along a railway line will seriously affect the safety and normal operation of railways, causing great economic and property losses. Existing rockfall monitoring and early warning methods still have shortcomings, such as accurate warning of single-point disasters and vulnerability to the natural environment. In this study, a rockfall test of a flexible safety protection net along the slope of a railway and a rockfall test of the railway track were carried out, and the vibration signals of the falling rock hitting the different sites of the protective net and hitting different positions of the rails were obtained. Using the signal analysis methods such as Fast Fourier Transformation and Short-Time Fourier Transform, the basic characteristics of the rockfall vibration signal and the vibration signal when the train passes and the propagation law of the rockfall vibration signal are obtained. Finally, a set of monitoring and early warning systems for rockfall disasters along the railway based on the analysis of vibration signal characteristics is established. The monitoring and early warning method has the advantages of all-weather, high-time, semi-automatic and high efficiency performance.

A Real-Time Detection Method for BDS Signal in Space Anomalies.

Signal In Space (SIS) anomalies in satellite navigation systems can degrade satellite-based navigation and positioning performance. The occurrence of SIS anomalies from the BeiDou navigation satellite System (BDS) may be more frequent than for the Global Positioning System (GPS). In order to guarantee the integrity of BDS users, detecting and excluding SIS anomalies is indispensable. The traditional method through the comparison between the final precision ephemeris and the broadcast ephemeris is limited by the issue of long latency of precision ephemeris release. Through the statistical characteristics analysis of Signal In Space User Range Error (SISURE), we propose a real-time Instantaneous SISURE (IURE) estimation method by using the Kalman filtering-based carrier-smoothed-code to detect and exclude BDS SIS anomalies, in which the threshold for BDS IURE anomaly detection are obtained from the integrity requirement. The experimental results based on 1 Hz data from ground observations show that the proposed method has an estimation accuracy of 1.1 m for BDS IURE. The test results show that the proposed method can effectively detect the SIS anomalies caused by either orbit faults or clock faults.

Susceptibility‐weighted imaging in malignant melanoma brain metastasis

The value of cerebral susceptibility-weighted imaging (SWI) in malignant melanoma (MM) patients remains controversial and the effect of melanin on SWI is not well understood. To systematically analyze the spectrum of intracerebral findings in MM brain metastases (BM) on SWI and to determine the diagnostic value of SWI. Retrospective. In all, 100 patients with melanoma BM (69 having received radiotherapy [RT] and 31 RT-naïve) and a control group of 100 melanoma patients without BM were included. For detailed analysis of signal characteristics, 175 metastases were studied. Gradient echo SWI sequence at 1.5, 3.0, and 9.4 T. Signal characteristics from melanotic and amelanotic BMs on SWI with a focus on blooming artifacts were analyzed, as well as the presence and longitudinal dynamics of isolated SWI blooming artifacts in patients with and without BM. Chi-squared and Student's t-test were used for contingency table measures and group data of signal and clinical characteristics, respectively. Melanotic and amelanotic metastases did not show significant differences of SWI blooming artifacts (38% vs. 43%, P = 0.61). Most metastases without an initial SWI artifact developed a signal dropout during follow-up (80%; 65/81). Isolated SWI artifacts were detected more frequently in patients with BM (20 vs. 9, P = 0.03), of which the majority were found in patients who had received RT (17 vs. 3, P = 0.08). None of these isolated SWI blooming artifacts turned into overt metastases over time (median follow-up: 8.5 months). Similar findings persisted as remnants of successfully treated metastases (88%; 7/8). We conclude that SWI provides little additional diagnostic benefit over standard T1 -weighted imaging, as melanin content alone does not cause diagnostically relevant SWI blooming. Signal transition of SWI may rather indicate secondary phenomena like microbleeding and/or metal scavenging. Our results suggest that isolated SWI artifacts do not constitute vital tumor tissue but represent unspecific microbleedings, RT-related parenchymal changes or posttherapeutic remnants of former metastatic lesions. 3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;50:1251-1259.

A New Geosynchronous SAR Constellation and its Signal Characteristics

The Geosynchronous Synthetic Aperture Radar (GEO SAR) has a long synthetic aperture time. The temporal decoherence and azimuth variance characteristics of echo are significant, that brings great challenges to signal to process. In order to reduce the synthetic aperture time and thus improve the observation flexibility and efficiency, this paper proposes a SAR system mounted on a special satellite in reverse equatorial geosynchronous orbit, so-called the reverse equatorial GEO SAR. The orbit is nearly circular and the orbital plane coincides with the equatorial plane. The satellite flies against the direction of the Earth's rotation. The relative velocity is accelerated twice and the synthetic aperture time is shorter. The satellite does not drift in latitude direction and drifts uniformly in longitude direction. The echo has azimuth invariance property. Meanwhile, the 24-hour continuous observation can be achieved for areas with a certain range of latitude by means of large squint technique and constellation design. As the GEO SAR has high orbit, large delay, large squint angle, and wide pulse width, the complex modulation effects are generated by continuous motion between the satellite and target during the imaging period. In this paper, the uniform acceleration curve motion is used to describe the motion of both satellite and target, and the linear approximation is used to describe the slant range change in the process of transmitting and receiving one pulse. Accordingly, an accurate signal model for the reverse equatorial GEO SAR is established, which provides a theoretical model for signal characteristics analysis and imaging algorithms development.

Improved power flow control strategy of the hybrid AC/DC microgrid based on VSM

The hybrid AC/DC microgrid with different types of distributed generations (DGs) and load demands is considered to be the preferred microgrid mode in the future. For hybrid AC/DC microgrid, autonomous and bidirectional power flow between AC and DC subgrids with superior dynamic performance is the fundamental objective to realise proportional power sharing and robust operation. In this study, an improved active power control strategy of the bidirectional AC/DC main converter (BMC) based on virtual synchronisation machine (VSM) for inertia improvement of the AC bus frequency and DC bus voltage of the hybrid microgrid is proposed. The VSM control is derived through the virtual inertia equation and the virtual capacitance equation, which can manage the AC frequency and DC voltage simultaneously. Then, the small signal and large signal characteristics analysis of the BMC are conducted to analyse the VSM control feature with different control parameters. On the basis of the small signal analysis, a proportional power sharing principle to select the control parameters is given to make DGs share the power commensurate with their power ratings. Finally, simulation cases are carried out to show the validity and efficiency of the proposed control strategy.

Analysis of signal characteristics from rock drilling based on vibration and acoustic sensor approaches

Lithological recognition is of great significance in oil drilling fields. To investigate the relationship between rock properties and the vibro-acoustic signal characteristics generated by drilling, a rock drilling vibration measurement system has been developed, and a relative drilling test is conducted indoors. This paper illustrates the application of a vibration sensor and a special wideband acoustic sensor method to distinguish the specific time–frequency characteristics generated by drilling in different types of rock. Furthermore, an intuitive comparison of these two approaches is performed. In particular, an acoustic focusing device was designed to assist the wideband acoustic condenser microphone in detecting specific signals during the drilling process. In addition, time-domain and time–frequency analyses were proposed to reveal the differences in signal characteristics generated by different kinds of rock. The results indicate that both the vibration spectral characteristics and the acoustic spectral characteristics from 4 types of rock show significant differences, which may be promising for lithological recognition using the feature model. However, the acoustic sensor approach, benefiting from the specially designed acoustic focusing device, presents a better signal-to-noise ratio than the vibration sensor approach.

TOPOISOMERASES: FEATURES OF THE ACTION, CLASSIFICATION, CELL FUNCTIONS, INHIBITION, ANTHRAFURANDION

Introduction. Topoisomerases influence on DNA topology and are capable of running down their super spiraling molecules by importation of one- or two-chained ruptures with the subsequent restitution and also the negative super rounds or catenae’s. Topoisomerases are known to be targets for antineoplastic therapy. Inhibitors of these enzymes of various nature and chemical structure are widely used for the suppression of tumor Topoisomerase I and/or II activity with the blocking cells in the phase G2 and a delay of their introduction in mitosis. Such difficult curable tumors as colorectal cancer, carcinoma of the stomach, non-small cell lung cancer and so forth are the most sensitive to these drugs. The search of perspective antineoplastic inhibitors is implemented generally in ranks of the non-camptothecin agents among which heterocyclic condensed nitrogenous compounds, in particular, anthrafurandiones show the most significant results. The review of thematic literature from 2011 to 2018 is devoted to the description of properties of topoisomerase as targets and their inhibitors from perspective classes. Objectives: 1. The analysis of signal characteristics of topoisomerases as targets for anticancer non-camptothecin inhibitors. 2. Identification of structure-activity relationship in the ranks of potential inhibitors of topoisomerases. 3. The choice of the most perspective non-camptothecin topoisomerase inhibitors among heterocyclic condensed nitrogenous compounds on the basis of the comparative analysis of structure and properties. Material and methods. Materials of 79 scientific articles published in the leading biological, biochemical and chemical journals of the different countries within the 8 last years are subjected to the analysis. The structure of the review meets the purpose and tasks of the scientific analysis. Results. The analysis of the thematic literature showed topoisomerases to be relevant targets for antineoplastic therapy of severe oncological pathology. In this regard, intensive search of various pharmaceuticals among topoisomerase inhibitors is performed in recent years. Researchers modify the known basic structures as well as synthesize new compounds. The discovery of a top-directional effect of the known medicines expands the data on their mechanism of the action. To identify the topoisomerase inhibitory activity of the drug the methods with the use of plasmid DNA is applied. The cytotoxic activity, apoptosis induction, including the caspases activation, modification of mitochondrial potential, influence on p53 and others are examined in parallel studies. The research directed on the identification of new effective non-camptothecin oral topoisomerase inhibitors among the anthracyclines derivatives are of undoubted relevance. Such agents, in contrast to Doxorubicin (anthracycline antibiotic widely used for tumor therapy), have moderate toxicity and allow to control the growth of solid tumors and leukemia in mono-therapy mode. Conclusion. In terms of searching of original antineoplastic agents, a class of heterocyclic condensed nitrogenous compounds, first of all, the anthraquinones showing properties of topoisomerase inhibitors is one of the most promising. The results of chemical and biological research of the compounds of this series were laid in a basis of the design of medicinal substances and their drug formulations. Prognostically significant data obtained in preclinical testing allow us to hope that obtained antitumor agents will be highly effective on a clinical stage of trials.

Сигнальные и шумовые параметры автодинов с мягкой импедансной характеристикой активного элемента (обзор)

The general expressions for an analysis of signal and fluctuation parameters and characteristics of an autodyne oscillator are obtained, which is under an influence of the proper reflected emission from a radar object. The oscillator model represented by a parallel connection of an oscillating system and an active element with the soft impedance characteristics, also takes into consideration the internal noises of the active element. The analysis results are presented for dependences of autodyne mentioned parameters and characteristics versus the oscillator operation mode and a value of the “softness” index of its impedance characteristics of the active element. Investigation results are necessary for engineering calculation of parameters and characteristics of the autodyne on the Gunn diode and other active elements base.

Characteristics Analysis of Postdemodulation Multipass Signal Combining for Mobile Communication

Characteristics Analysis of Postdemodulation Multipass Signal Combining for Mobile Communication

A Logarithmic Detection Scheme in BOTDR With Low-Bandwidth Requests

This paper presents a logarithmic detection scheme for reducing the bandwidth of the data acquisition (DAQ) in a Brillouin optical time domain reflectometer (BOTDR). From the analysis of signal features in frequency-scanning BOTDR, the reduction effect of the proposed detection scheme on the bandwidth of DAQ is investigated theoretically. We implement the scheme and evaluate its influence on the performance of BOTDR over a ~10-km sensing fiber by employing a digitalizer with bandwidth of only 50 MHz. The experimental results show that the spatial resolution of 1.02 m is achieved even though the bandwidth of DAQ is only 50 MHz. At 100-m end of sensing fiber, the root-mean-square error (RMSE) of Brillouin frequency shift (BFS) is 0.67 MHz corresponding to the strain error of 13.4 $\mu \varepsilon $ and temperature error of 0.66°C. As a comparison, the BFS is likewise acquired by a 200-MHz-bandwidth digitalizer, the RMSE of which is 0.66 MHz corresponding to the strain error of $13.2~\mu \varepsilon $ and temperature error of 0.65°C, nearly consistent with the former. It is confirmed that the logarithmic detection scheme can be used in BOTDR for reducing bandwidth request of DAQ meanwhile without excessive deterioration of spatial resolution or measurement accuracy.

Analysis of photoacousitc signal features from glucose solutions using a dual-wavelength light

Analysis of photoacousitc signal features from glucose solutions using a dual-wavelength light

Development of leakage test facility for leak signal characteristic analysis in water pipeline

Development of leakage test facility for leak signal characteristic analysis in water pipeline