Pulse Coupling Research Articles

Pulse Shape and Voltage-Dependent Synchronization in Spiking Neuron Networks.

Pulse-coupled spiking neural networks are a powerful tool to gain mechanistic insights into how neurons self-organize to produce coherent collective behavior. These networks use simple spiking neuron models, such as the θ-neuron or the quadratic integrate-and-fire (QIF) neuron, that replicate the essential features of real neural dynamics. Interactions between neurons are modeled with infinitely narrow pulses, or spikes, rather than the more complex dynamics of real synapses. To make these networks biologically more plausible, it has been proposed that they must also account for the finite width of the pulses, which can have a significant impact on the network dynamics. However, the derivation and interpretation of these pulses are contradictory, and the impact of the pulse shape on the network dynamics is largely unexplored. Here, I take a comprehensive approach to pulse coupling in networks of QIF and θ-neurons. I argue that narrow pulses activate voltage-dependent synaptic conductances and show how to implement them in QIF neurons such that their effect can last through the phase after the spike. Using an exact low-dimensional description for networks of globally coupled spiking neurons, I prove for instantaneous interactions that collective oscillations emerge due to an effective coupling through the mean voltage. I analyze the impact of the pulse shape by means of a family of smooth pulse functions with arbitrary finite width and symmetric or asymmetric shapes. For symmetric pulses, the resulting voltage coupling is not very effective in synchronizing neurons, but pulses that are slightly skewed to the phase after the spike readily generate collective oscillations. The results unveil a voltage-dependent spike synchronization mechanism at the heart of emergent collective behavior, which is facilitated by pulses of finite width and complementary to traditional synaptic transmission in spiking neuron networks.

Tip‐Enhanced Imaging and Control of Infrared Strong Light‐Matter Interaction

AbstractOptical antenna resonators enable control of light‐matter interactions on the nano‐scale via electron–photon hybrid states in strong coupling. Specifically, mid‐infrared (MIR) nano‐antennas coupled to saturable intersubband transitions in multi‐quantum‐well (MQW) semiconductor heterostructures allow for the coupling strength to be tuned through antenna resonance and field intensity. Here, tip‐enhanced nano‐scale variation of antenna‐MQW coupling across the antenna is demonstrated, with a spatially‐dependent coupling strength varying from 73 (strong coupling) to 24 (weak coupling). This behavior is modeled based on the spatially dependent local constructive and destructive interference between tip and antenna fields. Using a quantum‐mechanical density‐matrix model of the MQW system with its designed values of transition dipole moment, doping density, and population decay time, the picosecond IR pulse coupling to intersubband transitions and the associated tip induced strong‐field saturation effects are described. These results present a new regime of nonlinear IR light‐matter control based on the dynamic manipulation of quantum hybrid states on the nanoscale and in the infrared, with a perspective regarding extension to molecular vibrations.

Research on Transformer Multiple Fault Detection Based on Pulse Coupled Injection

Abstract The fault diagnosis method of winding deformation based on pulse coupling injection is becoming more and more popular due to its advantages of online detection. In order to further improve the method, a pulse generator with adjustable parameters is developed in this paper to provide stable excitation. Its amplitude is adjustable from 600v to 5000v, pulse width is adjustable from 100 to 1000ns, and frequency is adjustable from 1 to 20kHz. In the diagnosis of winding deformation, the current research mainly focuses on the single deformation fault, and rarely involves the mixed deformation fault. Therefore, based on the pulse coupling injection method, field experiments are carried out to verify the feasibility of the method and find out the important reasons affecting the curve. At the same time, the detection experiment of multi-winding deformation fault superposition of a transformer is carried out, and the RVM frequency divider is used to accurately diagnose the mixed fault types of transformer windings.

Common‐mode current reduction in EMP coupling with the star‐quad cable having a reference conductor

AbstractThe coupling of electromagnetic pulse (EMP) with the star‐quad cable having reference conductor is analyzed by using the proposed model, which is based upon multi‐conductor transmission line theory. Expressions for common‐mode (CM) and differential‐mode (DM) currents are developed. Two cases are mainly discussed: the first case is the star‐quad cable with a central reference conductor, and the second case with the outside reference conductor. A rigorous comparison between these two cases shows that when the reference conductor is placed at the center, the magnitude of CM current is reduced dramatically, which is beneficial for electromagnetic compatibility (EMC). The CM current magnitude of the outside reference conductor is relatively very high due to the large CM current loop area, which is the least possible for the central reference conductor. There is no significant change in the DM current magnitude for both cases because the DM current has no direct dependence on the CM current loop area. A commercial software, FEKO, which utilizes the method of momentum (MoM), is used to compare the results of our proposed method, which are in good agreement.

Analysis on the low-frequency electromagnetic pulse coupling to horizontal electrically short lines

In this study, we investigated the coupling features of the nuclear electromagnetic pulse (NEMP) on overhead cables in the middle-and-far regions, different from the transmission line model commonly used for field-line coupling in high-frequency cases, using a simpler lumped approximation to solve the electrically small size model in low-frequency cases. To verify its effectiveness, a simulation model with the same conditions was set up using the software of Computer Simulation Technology (CST), and cable coupling experiments were performed in a laboratory environment using a bounded-wave electromagnetic pulse simulator. The calculated results of the lumped approximation circuit were compared with the CST simulation and measured results, and the agreement was good. The results also shows that the load exhibits a differential response in the case of the low impedance and it is consistent with the excitation signal in the case of the high impedance. Finally, some more experiments were constructed to analyzed the effect of different cable parameters on the cable load response through experiments, and the experimental results are also in general agreement with the theoretical analysis, in which the induced signal of the low-impedance load is mainly determined by the magnetic field in the direction normal to the cable and the ground loop and the induced signal of the high-impedance load is mainly determined by the electric field in the direction of the height of the cable erection.

Environment analysis of high-altitude electromagnetic pulse coupling field in cavity with aperture shielding

Environment analysis of high-altitude electromagnetic pulse coupling field in cavity with aperture shielding

Study on coupling characteristics of different welding modes in laser-double TIG hybrid welding

In order to study the low-power pulsed laser-induced double arc coupling discharge effect and improve the energy utilization rate of the hybrid heat source, this paper adopts different heat source arrangement modes (laser-guided, double arc-guided) and conducts welding experiments under different Dla (distance between laser beam and two tungsten electrodes). The high-speed camera and spectral diagnostic system are used to monitor the dynamic behavior of arc plasma information, molten pool, and keyhole in real-time and calculate the characteristics of electron temperature and electron density of the coupled plasma. The physical model is established to analyze and discuss the time characteristics and energy distribution of coupled discharge. The results show that according to the different Dla, the hybrid heat source has three different coupling effects: laser and double arc interfere with each other, laser and double arc good coupling, laser and double arc no significant effect. When the laser and the double arc have a good coupling state, the coupled plasma has a lower electron temperature and a higher electron density. At this time, the Marangoni force and arc pressure on the liquid metal in the laser keyhole is enough to overcome its own gravity. The keyhole has existed for a long time, which is conducive to the extension of the laser-arc coupling discharge effect and improves the energy utilization efficiency of the hybrid heat source. Compared with the laser-guided mode, the double arc-guided mode has a larger coupling discharge period and duty cycle, and the energy density of the conductive region in the center of the keyhole increases by 14.4 %, which is beneficial to improve the energy utilization efficiency of the hybrid heat source and obtain a larger penetration depth.

Pulsed electromagnetic field coupling to a transmission line with arbitrary loads—A unified methodology based on reciprocity

A unified description of the time-domain (TD) electromagnetic (EM) field coupling to a transmission line (TL) that is terminated by arbitrary linear time-invariant loads is presented. Closed-form expressions for the electric current induced in the loads are derived with the aid of the EM reciprocity theorem of the time-convolution type. The validity of the solution is demonstrated via illustrative numerical examples.

Design of Self-Integrating Transient Surface Current Density Sensor Integrated Fiber Transmission Link.

The transient surface current density reflects the external coupling of the electromagnetic pulse (EMP) to the tested device. In this paper, the generation mechanism and measurement principle of conductor surface current density are introduced, and the surface current density distribution irradiated by EMP on a typical aircraft structure is simulated and analyzed. The traditional surface current density is usually measured by B-dot antenna, but its output signal is the differential of the measured signal, so additional integrators or numerical integration of the measured data are required. In this paper, a self-integrating surface current sensor based on optical fiber transmission is designed based on the shielded loop antenna with gap structure. The output signal is the real signal waveform to be measured. Compared with coaxial cables, integrated optical fiber transmission improves the anti-interference ability of long-distance transmission signals. At the same time, the design process of the sensor is introduced in detail. The bandwidth of the sensor is 300 kHz~500 MHz, the sensitivity is calibrated at 1.23 (A·m-1)/mV, and the dynamic range is ±25~1400 A·m-1 (35 dB). The surface current of a metal plate is measured in a bounded wave electromagnetic pulse simulator using a detector developed in this paper. The test results show that the developed sensor has good engineering applicability.

Simulation analysis of visual perception model based on pulse coupled neural network

Pulse-coupled neural networks perform well in many fields such as information retrieval, depth estimation and object detection. Based on pulse coupled neural network (PCNN) theory, this paper constructs a visual perception model framework and builds a real image reproduction platform. The model firstly analyzes the structure and generalization ability of neural network multi-class classifier, uses the minimax criterion of feature space as the splitting criterion of visual perception decision node, which solves the generalization problem of neural network learning algorithm. In the simulation process, the initial threshold is optimized by the two-dimensional maximum inter-class variance method, and in order to improve the real-time performance of the algorithm, the fast recurrence formula of neural network is derived and given. The PCNN image segmentation method based on genetic algorithm is analyzed. The genetic algorithm improves the loop termination condition and the adaptive setting of model parameters of PCNN image segmentation algorithm, but the PCNN image segmentation algorithm still has the problem of complexity. In order to solve this problem, this paper proposed an IGA-PCNN image segmentation method combining the improved algorithm and PCNN model. Firstly, it used the improved immune genetic algorithm to adaptively obtain the optimal threshold, and then replaced the dynamic threshold in PCNN model with the optimal threshold, and finally used the pulse coupling characteristics of PCNN model to complete the image segmentation. From the coupling characteristics of PCNN, junction close space of image and gray level characteristics, it determined the local gray mean square error of image connection strength coefficient. The feature extraction and object segmentation properties of PCNN come from the spike frequency of neurons, and the number of neurons in PCNN is equal to the number of pixels in the input image. In addition, the spatial and gray value differences of pixels should be considered comprehensively to determine their connection matrix. Digital experiments show that the multi-scale multi-task pulse coupled neural network model can shorten the total training time by 17 h, improve the comprehensive accuracy of the task test data set by 1.04%, and shorten the detection time of each image by 4.8 s compared with the series network model of multiple single tasks. Compared with the traditional PCNN algorithm, it has the advantages of fast visual perception and clear target contour segmentation, and effectively improves the anti-interference performance of the model.

High-power Microwave Damage Assessment Method for UAV

To evaluate the damage assessment of high-power microwaves on complex electronic systems, a damage assessment method combining top-down system analysis and bottom-up comprehensive evaluation is proposed. A UAV damage tree model was constructed, and the FAHP-CRITIC method was used to assign weights to system components. The pulse energy transfer and coupling process are analyzed, and a neural network system is introduced to predict the damage degree of the parts considering the influencing factors of the damage degree of the parts. Based on the obtained component weights and damage degree, the system damage degree is calculated by the constructed nonlinear discontinuity function which satisfies the serial structure of the electronic system. Then, the mapping of system damage degree to ruin level is realized through the affiliation function. Finally, simulation calculations are carried out for the UAV to verify the feasibility and effectiveness of the proposed method.

Portable nanosecond laser for handheld laser-induced breakdown spectroscopy instruments

The portable laser is indispensable for handheld laser-induced breakdown spectroscopy (LIBS) instruments. We developed a passive, Q-switched pulsed, Nd:YAG laser system with small size and low cost. The maximum pulse energy of the laser was 10 mJ and the pulse duration was <2 ns. The peak power was >5 MW. The laser exhibited very high stability without any cooling system and its relative standard deviation of the pulse energy was <0.2 % . The laser was also used as a light source of LIBS to measure the concentrations of Cr, Cu, Mn, and Ni in alloys. The experimental results show that the determination coefficient of the calibration curves for these four elements is all better than 0.99. For its shorter pulse duration, the laser can decrease the plasma shield effect to improve the coupling of laser pulse and the target and stability of spectra intensity. The portable laser developed is a good laser source for handheld LIBS instruments.

Effect of nonlinear lensing on the coupling of ultrafast laser pulses to hollow-core waveguides.

Gas-filled hollow-core fibers are a flexible platform for the manipulation of ultrafast laser pulses through a variety of nonlinear optical effects. Efficient high-fidelity coupling of the initial pulses is very important for system performance. Here we study the effect of self-focusing in gas-cell windows on the coupling of ultrafast laser pulses into hollow-core fibers using (2+1)-dimensional numerical simulations. As expected, we find that the coupling efficiency is degraded and the duration of the coupled pulses changed when the entrance window is too close to the fiber entrance. The interplay of nonlinear spatio-temporal reshaping and the linear dispersion of the window create different results depending on the window material, pulse duration, and pulse wavelength, with longer-wavelength beams more tolerant of high intensity in the window. While shifting the nominal focus to compensate can restore some of the lost coupling efficiency, it improves the pulse duration only marginally. From our simulations we derive a simple expression for the minimum distance between the window and the HCF entrance facet. Our results have implications for the often space-constrained design of hollow-core-fiber systems, especially where the input energy is not constant.

Enhancement of Flue Gas Low-Concentration Toluene Removal in Pulsed Plasma Coupling with Porous Ceramic Modified Catalyst Reactor

A novel coaxial pulsed plasma coupling with porous ceramic tube modified by Co/Mn oxide catalyst reactor was used to remove low-concentration toluene from the flue gas. The pulsed plasma coupling with catalyst (PPCC) reactor was designed according to actual process conditions, including temperature, initial concentration, residence time, and so on. The PPCC reactor was used for the generation of plasma and consisted of a porous ceramic membrane tube (CMT) with catalyst pressed on the inner wall and an electrode at the center. The simulated flue gas flowed into the PPCC reactor according to in-plasma catalysis (IPC) or postplasma catalysis (PPC) models. At concentrations lower than 100 ppm, the PPCC reactor mainly decomposed toluene to CO2 and CO. The Co1Mn0.11-CMT (Co/Mn = 1:0.11) catalyst showed the best degradation efficiency of 97.7% and CO2 selectivity of 93.8% with a specific energy density of approximately 800 J/L by the PPC model. The byproduct O3 was also detected and discussed. Finally, the related reaction mechanism was explained by DFT calculations. This study guides engineering application of PPCC technology.

Efficient free-space to on-chip coupling of THz-bandwidth pulses for biomolecule fingerprint sensing.

Wide bandwidth THz pulses can be used to record the distinctive spectral fingerprints related to the vibrational or rotational modes of polycrystalline biomolecules, and can be used to resolve the time-dependent dynamics of such systems. Waveguides, owing to their tight spatial confinement of the electromagnetic fields and the longer interaction distance, are promising platforms with which to study small volumes of such systems. The efficient input of sub-ps THz pulses into waveguides is challenging owing to the wide bandwidth of the THz signal. Here, we propose a sensing chip comprised of a pair of back-to-back Vivaldi antennas feeding into, and out from, a 90° bent slotline waveguide to overcome this problem. The effective operating bandwidth of the sensing chip ranges from 0.2 to 1.15 THz, and the free-space to on-chip coupling efficiency is as high as 51% at 0.44 THz. Over the entire band, the THz signal is ∼42 dB above the noise level at room temperature, with a peak of ∼73 dB above the noise. In order to demonstrate the use of the chip, we have measured the characteristic fingerprint of α-lactose monohydrate, and its sharp absorption peak at ∼0.53 THz was successfully observed, demonstrating the promise of our technique. The chip has the merits of efficient in-plane coupling, ultra-wide bandwidth, ease-of-integration, and simple fabrication. It has the potential for large-scale manufacture, and can be a strong candidate for integration into other THz light-matter interaction platforms.

The Possible Role of Electrical Stimulation in Osteoporosis: A Narrative Review.

Osteoporosis is mainly a geriatric disease with a high incidence, and the resulting spinal fractures and hip fractures cause great harm to patients. Anti-osteoporosis drugs are the main treatment for osteoporosis currently, but these drugs have potential clinical limitations and side effects, so the development of new therapies is of great significance to patients with osteoporosis. Electrical stimulation therapy mainly includes pulsed electromagnetic fields (PEMF), direct current (DC), and capacitive coupling (CC). Meanwhile, electrical stimulation therapy is clinically convenient without side effects. In recent years, many researchers have explored the use of electrical stimulation therapy for osteoporosis. Based on this, the role of electrical stimulation therapy in osteoporosis was summarized. In the future, electrical stimulation might become a new treatment for osteoporosis.

The protection design method of the engine control system under electromagnetic pulses.

This study assessed the survivability of an engine control system under intense electromagnetic pulses. It investigated the electromagnetic sensitivity of the system under the action of intense electromagnetic pulses. In this work, the evaluation focuses on the terminal circuit of the control system. It proposes a co-design method for electromagnetic pulse protection circuits on a printed circuit board. The electromagnetic interference mechanism and phenomena were analyzed through simulation and experiments. The electromagnetic susceptibility of the control system was tested using the bulk current injection test method, and the pulse coupling signal of the sensitive part was obtained. Subsequently, the terminal circuit was analyzed using a numerical calculation method. The pulse coupling signal was injected into the terminal circuit. Thus, we can determine why the control system exhibits sensitive phenomena. Then, a protection circuit of the terminal circuit was established. The design method's advantage is accurately locating the circuit's sensitive points and reducing the controller circuit's electromagnetic sensitivity by designing the circuit without drastically changing the original circuit. At the same time, the redundancy of protection circuit design can be effectively reduced.

Implementation of Hebb's rules in a network of excitable chemical cells coupled by pulses.

A network of four excitable cells with the Belousov-Zhabotinsky (BZ) reaction is considered both theoretically and experimentally. All cells are coupled by pulses with time delays τnj between the moment of a spike in cell #n and the moment of the corresponding perturbation of an addressee (cell #j). The coupling strengths of all connections except the coupling strength C12 between cells #1 and #2 are constant. Cell #1 is periodically perturbed (with period Tex) and sends pulses to cell #2. The value of C12 is controlled by pulses from two other cells (with indexes #5 and #6; cells with indexes #3 and #4 are absent in the considered network), provided the pulses from cell #5 increase C12, while the pulses from cell #6 decrease C12. Cells #5 and #6 are mutually coupled by inhibitory pulses. Depending on the relations between the values of τnj, there are three dynamic modes in the network: (i) the coupling strength C12 increases stepwise, which is the "Hebb mode", (ii) the C12 decreases stepwise, which is the "anti-Hebb mode", and (iii) the C12 remains almost unchanged within some small adjustable range, which is the meander mode. The ability to tune the C12via "Hebb" and "anti-Hebb" modes introduces memory in the chemical network and, consequently, a mechanism of learning can be realized. The theoretical network is implemented experimentally using four microcells with the BZ reaction provided the pulse coupling between microcells is realized using optical links.

Simulation analysis of electromagnetic pulse susceptibility and hardening design for system-in-package SZ0501

The electromagnetic pulse (EMP) susceptibility of System-in-Package (SiP) SZ0501 was investigated by field-circuit combination simulation method in this paper. The electromagnetic pulse coupling model of the SiP is established by an electromagnetic field simulation software (CST). Considering different incident and electric field direction, the type and distribution of pins, the coupled voltages via pins of the SiP under EMP were obtained to analyze the electromagnetic susceptibility of the SiP. Simulation results indicate five major factors affecting the electromagnetic susceptibility of the SiP: the effective electric field integration on the pins, the distribution of pins, the terminal cases of pins, the shunt effect of the output ports of the power plane, and the kind of ground planes. And compared with side incidence, SiP is more sensitive to EMP from above. Finally, some factors affecting the shielding effect are considered, a shielding box is designed and then verified to reduce the electromagnetic susceptibility.

Plasticity in networks of active chemical cells with pulse coupling.

A method for controlling the coupling strength is proposed for pulsed coupled active chemical micro-cells. The method is consistent with Hebb's rules. The effect of various system parameters on this "spike-timing-dependent plasticity" is studied. In addition to networks of two and three coupled active cells, the effect of this "plasticity" on the dynamic modes of a network of four pulse-coupled chemical micro-cells unidirectionally coupled in a circle is studied. It is shown that the proposed adjustment of the coupling strengths leads to spontaneous switching between network eigenmodes.