Analysis of Aluminum Alloy Double-Pulse MIG Welding Arc Signal Characteristics Based on Broadband Mode Decomposition

Welding voltage and current in arc signals are directly related to arc stability and welding quality.Process experiments with different parameters were organized according to the orthogonal experimental design method by constructing an aluminum alloy double-pulse metal inert gas(MIG)welding arc electric signal test platform.The data acquisition system of the aluminum alloy MIG welding process was established to obtain real-time arc signal information reflecting the welding process.The aluminum alloy’s collected double-pulse arc current signals are decomposed adaptively by broadband mode decomposition(BMD).The direct current(DC)signal,pulse signal,distortion signal,ripple signal,and noise signal are separated and extracted,and the composite multiscale fuzzy entropy(CMFE)is calculated for the component set of the electrical signal.The experimental results show that the current waveform obtained by the double-pulse MIG welding current signal is consistent with the corresponding weld forming diagram.Simultaneously,the composite multiscale fuzzy entropy is calculated for the arc characteristic parameters.The rationality of matching process parameters and arc stability of aluminum alloy’s double-pulse MIG welding were evaluated.

Analysis of Driving Psychological Load in V-Shaped Subsea Tunnels Considering Driver Skin Electrical Signals

To examine the variation law of the driving psychological load in subsea tunnels under different illumination and longitudinal slope conditions,22 drivers were recruited to participate in a real vehicle test in off peak hours under similar traffic conditions,and the skin electric signals of the drivers in the free flow state were collected.Considering the skin conductance level(SCL)as the load characteristic index,the influence of the different illuminance and slope conditions on the drivers’skin electrical signals was analyzed,and a measurement model of the relationship between the uphill and downhill slopes,illuminance and driver’s SCL value was constructed.The results indicate that the illuminance change rate and driver’s SCL are positively correlated.A larger illuminance change rate leads to an increase in the SCL and psychological workload of the driver.The influence of the uphill and downhill slopes on the driver’s SCL value in different areas of the subsea tunnel is considerably different.With the increase in the degree of the uphill and downhill slopes,the driver’s SCL value increases,and the maximum SCL appears in a slope range of 3.5%–4%.Moreover,the SCL of the drivers in the downhill section is higher than that in the uphill section,corresponding to a larger driving psychological load.

CHARACTERISTICS OF HERBIVORY/WOUND-ELICITED ELECTRICAL SIGNAL TRANSDUCTION IN TOMATO

Electrical signals commonly occur in plants in response to various environmental changes and have a dominant function in plant acclimation.The transduction of wound-elicited electrical signals in the model plant spedes Arabidopsis has been characterized but the characteristics of electrical signal transduction in response to herbivory or wounding in crop species remain unknown.Here,the features of electrical signals elicited by insect herbivory and wounding in tomato were investigated.Unlike those in Arabidopsis,wounding tomato leaves did not cause leaf-to-leaf electrical signal transduction.In contrast,electrical signals elicited in response to petiole wounding were stronger and more strongly transduced.Leaflet wounding also activated electrical signal transduction and jasmonic acid(JA)signaling within the whole compound leaf.It was also demonstrated that tomato glutamate receptor-like 3.3(GLR3.3)and GLR3.5 mediated leaflet-to-leaflet electrical signal transduction.Herbivory-induced JA accumulation and Helicoverpa armigera resistance were reduced in glr3.3/3.5 plants.This work reveals the nature of electrical signal transduction in tomato and emphasizes the key roles of GLR3.3 and GLR3.5 in electrical signal transduction and JA signaling activation.

On Similarities and Differences of Invasive and Non-Invasive Electrical Brain Signals in Brain-Computer Interfacing

We perceive that some Brain-Computer Interface (BCI) researchers believe in totally different origins of invasive and non-invasive electrical BCI signals. Based on available literature we argue, however, that although invasive and non-invasive BCI signals are different, the underlying origin of electrical BCIs signals is the same.

Seismic electric signals in seismic prone areas

The Varotsos-Alexopoulos-Nomicos （VAN） method of short-term earthquake prediction was introduced in the 1980s. The VAN method enables estimation of the epicenter, magnitude and occurrence time of an impending earthquake by observing transient changes of the electric field of the Earth termed seismic electric signals （SES）. Here, we present a few examples of SES observed in various earthquake prone areas worldwide.

A novel wavelet method for electric signals analysis in underwater arc welding

Electric signals are acquired and analyzed in order to monitor the underwater arc welding process. Voltage break point and magnitude are extracted by detecting arc voltage singularity through the modulus maximum wavelet （MMW） method. A novel threshold algorithm, which compromises the hard-threshold wavelet （HTW） and soft-threshold wavelet （STW） methods, is investigated to eliminate welding current noise. Finally, advantages over traditional wavelet methods are verified by both simulation and experimental results.

Stability of fiber laser-MIG hybrid welding of high strength aluminum alloy

The effect of fiber laser on MIG arc was investigated with 8 mm 7075-T6 high strength aluminum alloy as base material.The arc shape,droplet transfer form and electrical signal in the process of MIG welding and laser-MIG hybrid welding were analyzed.The stability of the hybrid welding process was evaluated by standard deviation analysis.The results show that with the increase of laser power,a large number of laser-induced plasma enters the arc column area,providing more conductive channels,which makes the heat of MIG arc more concentrated and the short circuit transition disappear.Due to the continuous effect of laser,the keyhole becomes a continuous electron emission source,and a stable cathode spot will be formed near the keyhole,which enhances the stability of MIG arc at the base current state.By using the method of standard deviation analysis,the voltage standard deviation of single MIG welding arc and laser-MIG hybrid arc within 4 seconds was calculated.The standard deviation of single MIG arc voltage was 1.05,and the standard deviation of MIG arc voltage in laser-MIG hybrid welding was 0.71–0.86,so the hybrid welding process was more stable.

Understanding the changing mechanism of arc characteristics in ultrasound-magnetic field coaxial hybrid gas tungsten arc welding

Ultrasound-magnetic field coaxial hybrid Gas Tungsten Arc Welding(U-M-GTAW)is proposed as a means to control arc characteristics.The arc characteristics and the mechanism to change them,in an ultrasound-magnetic field coaxial hybrid GTAW,were studied by both experimental and theoretical analyses.The results showed that a periodic rotation and compression of the arc shape were obtained in U-M-GTAW and the arc energy was also enhanced.The most obvious compression of the arc shape in U-M-GTAW was obtained,compared with GTAW,M-GTAW and U-GTAW.At the same time,a periodic rotation of the arc was observed in U-M-GTAW.The geometric parameters of the arc shape in U-M-GTAW are reduced more than double compared with traditional GTAW.The arc voltage in the hybrid GTAW was increased,especially in the U-M-GTAW.The electromagnetic force and acoustic radiation force were the main factors for the change of arc characteristics in the U-M-GTAW.

Identifying the occurrence time of an impending major earthquake:a review

The procedure through which the occurrence time of an impending major earthquake can be determined is reviewed in the light of the recent advances. This can be achieved by analyzing in natural time the seismicity in the candidate area. To apply this general procedure, we need two important elements： first, to know when we should start the analysis, i.e., set the natural time equal to zero. This is the time at which the system enters the critical stage. Second a reliable estimation of the candidate epicentral area. If geoelectrical measurements are taken and the VAN method （after the initials of the three researchers Varotsos, Alexopoulos and Nomicos）is applied, both these elements become available upon the recording of a precursory Seismic Electric Signals （SES） activity, because its initiation marks the time when the system enters the critical stage, and in addition the SES data enable the determination of the epicentral area of the impending mainshock. On the other hand, if geoelectrical data are lacking, we make use of the following two recent findings by means of natural time analysis： First, the fluctuations of the order parameter of seismicity in a large area exhibit a minimum a few months before a major earthquake almost simultaneously with the initiation of an SES activity. Second, a spatiotemporal study of this minimum unveils an estimate of the epicentral area of the impending major earthquake. Two examples are given that refer to the strongest earthquakes that occurred in Greece and Japan during the last 3 decades, i.e., the Mw6.9 earthquake in southwestern Greece on 14 February 2008 and the Mw9.0 Tohoku earthquake in Japan on 11 March 2011.

Effects of Electric Stimulations Applied During Absolute Refractory Period on Ventricular Muscle from Rabbits

Objectives To investigate the influences of electric signals applied during absolute refractory period (ARP) on the contractility of isolated papillary muscle from rabbits. Methods Papillary muscle was exercised from the right ventricle and was paced at 1 Hz. Biphasic square wave current pulse was delivered during the absolute refractory period (called CCM) in isolated, superfused, isometrically contractility rabbit papillary muscle. The peak tension (PT) of papillary muscle, as well as maximum positive tension change ( + dT/dtmax), were observed. Results Compared with the baseline, both PT and + dT/dtmax significantly increased during CCM stimulation by 18.2% and 21.4% respectively (P < 0. 05) . In addition, PT increased significantly with one or two beats following CCM signal application and reached a. new steady state level after a few beats. Once the CCM signals were turned off, the PT returned to the approximately baseline level ( P < 0. 05). Moreover, the effect of CCM on PT was dose - response to voltage. The obvious effect was at higher voltage. No effect was observed at lower voltage. Conclusions Electric signals delivered during the absolute refractory period can rapidly enhance the contractility of myocardium, which suggests that CCM signal is a novel potent method for contractility modulation.

Mw9 Tohoku earthquake in 2011 in Japan:precursors uncovered by natural time analysis

This paper reviews the precursory phenomena of the 2011 Mw9 Tohoku earthquake in Japan that emerge solely when we analyze the seismicity data in a new time domain termed natural time. If we do not consider this analysis, important precursory changes cannot be identified and hence are missed. Natural time analysis has the privilege that enables the introduction of an order parameter of seismicity. In this frame, we find that the fluctuations of this parameter exhibit an unprecedented characteristic change, i.e., an evident minimum, approximately two months before Tohoku earthquake, which strikingly is almost simultaneous with unique anomalous geomagnetic field variations recorded mainly on the z component. This is consistent with our finding that such a characteristic change in seismicity appears when a seismic electric signal （SES） activity of the VAN method （from the initials of Varotsos, Alexopoulos, Nomicos） initiates, and provides a direct confirmation of the physical interconnection between SES and seismicity.

Development of Welding Multi-Information Remote Wireless Monitoring System Based on STM32

A single sensor is used to obtain welding information in welding monitoring process, but this method has some shortcomings. In order to obtain more comprehensive and reliable welding information, this paper designed and built a welding multi-information wireless monitoring system with STM32-F407ZET6 as the control core and ALK8266 as the wireless transmission module. Real-time acquisition, transmission and display of electric arc signal and welding image information are realized in the monitoring system. This paper mainly introduces the hardware and software core of the monitoring system. At the same time, the signal collected by the monitoring system is compared with the original signal, and the accuracy of the remote monitoring system is tested. The monitoring system is used in welding test. The test results show that the accuracy of the monitoring system meets the requirements, and the on-line monitoring of electric arc signal and welding image can be realized in the welding process.

Identifying the occurrence time of an impending mainshock:a very recent case

The procedure by means of which the occurrence time of an impending mainshock can be identified by analyzing in natural time the seismicity in the candidate area subsequent to the recording of a precursory seismic electric signals（SES） activity is reviewed. Here, we report the application of this procedure to an MW5.4 mainshock that occurred in Greece on 17 November 2014. This mainshock（which is pretty rare since it is the strongest in that area for more than half a century） was preceded by an SES activity recorded on 27 July 2014, and the results of the natural time analysis reveal that the system approached the critical point（mainshock occurrence） early in the morning on 15 November 2014.

A Simple Configuration for 40 Gbit/s CSRZ Signal Generation with Electrical Band-Limiting to Achieve Large Dispersion Tolerance

We present a novel configuration for carrier suppressed return-to-zero (CSRZ) signal generation, which only requires a single stage Mach-Zehnder (MZ) modulator in conjunction with an electrical mixer. Electrical band-limiting is also introduced to increase dispersion tolerance without causing additional penalty due to nonlinear effects in long haul dense wavelength division multiplexed (DWDM) CSRZ systems using conventional launch power levels.

Liquid metal-based plant electronic tattoos for in-situ monitoring of plant physiology

Flexible plant sensors,as a noninvasive and real-time monitoring method for plant physiology,are becoming crucial for precision agriculture.However,integrating flexible devices with plants are challenging due to their fragility and complex surfaces.In this study,we introduce a liquid metal-based plant electronic tattoo(LM-PET)that can harmlessly and continuously monitor the loss of water content and plant electrical signals,which are critical parameters for analyzing plant physiological status.The LM-PET achieves double-sided conductivity through soluble electrostatic spinning films and transferring technology,effectively addressing the issue of mismatch between the rigid interface of electronic devices and the surface of delicate plants.The fabricated tattoo electrode can adhere tightly to the leaf surface for a long time and can significantly broaden the scope of moisture monitoring,even in cases of severe wrinkling caused by water loss.At the optimum operating frequency of 100 kHz,the sensitivity of LM-PET can reach 25.4 kΩ%^(-1).Thus,LM-PETs can record the electrical signals generated when abiotic stresses threaten plants.They are also significant in providing a deeper understanding of the drought adaptation mechanisms of plants and developing drought-resistant varieties.They offer data-driven crop management and decision-making guidance,which is imperative for advancing precision agriculture.Overall,our findings provide valuable insights into the performance of agricultural inputs and facilitate real-time monitoring of plant growth and development.

Fish forewarning of comprehensive toxicity in water environment based on Bayesian sequential method

Environmental impact of pollutants can be analyzed effectively by acquiring fish behavioral signals in water with biological behavior sensors. However, a variety of factors, such as the complexity of biological organisms themselves, the device error and the environmental noise, may compromise the accuracy and timeliness of model predictions. The current methods lack prior knowledge about the fish behavioral signals corresponding to characteristic pollutants, and in the event of a pollutant invasion, the fish behavioral signals are poorly discriminated. Therefore, we propose a novel method based on Bayesian sequential,which utilizes multi-channel prior knowledge to calculate the outlier sequence based on wavelet feature followed by calculating the anomaly probability of observed values. Furthermore, the relationship between the anomaly probability and toxicity is analyzed in order to achieve forewarning effectively. At last, our algorithm for fish toxicity detection is verified by integrating the data on laboratory acceptance of characteristic pollutants. The results show that only one false positive occurred in the six experiments, the present algorithm is effective in suppressing false positives and negatives, which increases the reliability of toxicity detections, and thereby has certain applicability and universality in engineering applications.