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To calibrate non-contact sensors with fast response and high scale factor, it is critical to develop step pulse generators capable of generating standard high voltage step pulses and accurately measuring the generated waveform. In this paper, two types of step pulse generators are designed with output voltages of 2 kV and 100 kV. The 2 kV step pulse generator can generate a step pulse with a rise time of ~300 ps and an adjustable pulse width. A step pulse with a rise time less than 5 ns and a pulse width over 1 s can be generated with the 100 kV step pulse generator. The uncertainty of 2 kV step pulse generator is then analyzed by simulations and experiments. Finally, a performance comparison with step pulse generators in previous studies is carried out. Bandwidth, linearity and repeatability of the sensors can be verified with the designed two step pulse generators.

This study numerically simulated and investigated the flow field characteristics of a typical dual-pulse solid rocket motor with a soft pulse separation device through thermal insulation ablation under high-temperature dual-pulse erosion. The ablation rate of ethylene -propylene-diene monomer (EPDM) insulator was measured after the experiment. Experimental results were analyzed through scanning electron microscopy and microcomputed tomography. The ablation mechanism of the EPDM insulator under the operation conditions of a dual-pulse solid rocket motor was evaluated by analyzing the results. The results reveal that the internal flow field of the motor with a soft pulse separation device is uniform. The original charred layer existing on the EPDM insulator surface in the first pulse combustor is the decisive factor affecting the final ablation rate of the dual-pulse motor during the second pulse operation, and the ablation characteristic region is easily formed with the exfoliation of the charred layer. The ablation rate difference of the insulator increases with gas velocity.

Selective harmonic elimination pulsewidth modulation (SHEPWM) is a modulation technique widely used to improve the efficiency and harmonic content in medium-voltage high-power converters. Among these converters, the three-level neutral-point-clamped (3L-NPC) converter is one of the most utilized topologies. However, the 3L-NPC converter requires a proper balancing of dc-link capacitor voltages. This paper presents a control technique, based on pulse shifting method, to regulate the neutral point voltage when SHE-PWM is utilized. The proposed technique performs well with any power factor and it can also be directly applied to T-type converters and easily extrapolated to other multilevel topologies. The proposed method is experimentally validated in a scaled-down power converter and a full-scale medium-voltage 3L-NPC converter.

We study the quantum interference between the excitation pathways in a three-level $\Lambda$-type atom interacting with two short laser pulse trains under the conditions of electromagnetically induced transparency. The probability amplitude equations which describe the interaction of a three-level $\Lambda$-type atom with two laser pulse trains are numerically solved. We derive analytical expressions for the population of the upper excited state for resonant laser pulse trains with a rectangular temporal profile. By varying the parameters of the laser pulse trains such as area of a single pulse, detuning, repetition period, and number of individual pulses, we analyze the quantum interference between the excitation pathways in terms of the upper excited state population.

The intersecting cortical model (ICM), initially designed for image processing, is a special case of the biologically inspired pulse-coupled neural-network (PCNN) models. Although the ICM has been widely used, few studies concern the internal activities and firing conditions of the neuron, which may lead to an invalid model in the application. Furthermore, the lack of theoretical analysis has led to inappropriate parameter settings and consequent limitations on ICM applications. To address this deficiency, we first study the continuous firing condition of ICM neurons to determine the restrictions that exist between network parameters and the input signal. Second, we investigate the neuron pulse period to understand the neural firing mechanism. Third, we derive the relationship between the continuous firing condition and the neural pulse period, and the relationship can prove the validity of the continuous firing condition and the neural pulse period as well. A solid understanding of the neural firing mechanism is helpful in setting appropriate parameters and in providing a theoretical basis for widespread applications to use the ICM model effectively. Extensive experiments of numerical tests with a common image reveal the rationality of our theoretical results.

Wood poles are widely used to support overhead distribution and transmission power lines in North America and the world. These poles are vulnerable to internal deterioration due to extreme weather conditions, requiring a large number of poles to be inspected every year. This paper presents a comparative study of four stress wave-based nondestructive testing (NDT) methods commonly used for condition assessment of wood poles. These include the traditional approaches of sounding, sonic pulse velocity, and ultrasonic pulse velocity tests; and a new approach that considers the orthotropic characteristics of wood, uncertainties in the elastic properties, ultrasonic wave velocity and attenuation. Two poles with an internal hole of 4% of the cross-section are evaluated and compared by each method. Ultrasonic measurements of wave velocity and attenuation considering orthotropic characteristics of wood and uncertainties in the elastic properties provide a reliable wave-based NDT method for the detection of early decay in wood poles.

This article presents the spatial and temporal dynamics of high-power Gaussian laser pulse in relativistic plasma. At higher intensities, the self-focusing and self-compression of laser pulse take place due to the variation in the mass of plasma electrons moving with speed comparable to the speed of light. The two non-linear coupled differential equations for spatial and temporal pulsewidth parameters have been obtained using the moment theory approach. These equations have been solved numerically using the Runga-Kutta method. The variation in the spatial and temporal pulsewidth parameters with the distance of propagation is then used to calculate the energy gained by the electrons, which are trapped by the excited electron plasma wave during laser-plasma interaction. It is observed that spatio-temporal dynamics play an important role in electron acceleration in relativistic plasma.

Deinterleaving mixtures of radar pulse sequences is the first and the most vital step for modern electronic reconnaissance systems to intercept and analyze the intentions of non-cooperative radars. Currently, these systems are facing great challenges due to the emerging complexity of radar modulations. This paper proposes a novel method for deinterleaving mixtures of radar pulse sequences based on the time series characteristics of each source (component pulse sequences). Firstly, the mathematical representations are established to describe the structural characteristics of each source. Then, the deinterleaving problem is formulated as a minimization of a maximum-likelihood cost function that can be solved efficiently through a supervised neural machine translation (NMT) network, i.e. to translate each received pulse in the interleaved pulse sequence to the corresponding source label. A sequence-to-sequence NMT model is proposed to capture the structural relationships among the non-adjacent pulses originated from the same source in the mixtures and assign the corresponding label to each pulse. The proposed method does not require the exact knowledge of each component pulse sequence. The experimental results based on the time of arrival sequence of mixed pulse sequences show that the proposed method outperforms the state-of-the-art deinterleaving methods and achieves satisfactory performance under highly non-ideal situations with measuring noise and lost pulse conditions. The proposed method can be directly applied to other fields involving deinterleaving problems and multi-variate input conditions.

Intentional electromagnetic interference is a serious threat to the safety of electronic devices. Multiple electromagnetic pulses will be coupled and transmitted to electronic devices through the cables. Accumulative effects are generated, which make it easier for damage to occur in the electronic devices. In this article, the working principle of micro-silicon acceleration sensors is introduced. The accumulative effects of multiple pulses on acceleration sensors is studied by a large number of injection experiments. The accumulation trends of multiple pulses with different pulse numbers and intervals are analyzed. The damaged structures inside abnormal sensor amplifiers were observed via optical microscopy and scanning electron microscopy. The experimental results show that the accumulative effect is strengthened with increased pulse number or decreased pulse interval, and the threshold voltage for multiple pulses on the acceleration sensor decreases. The threshold voltage for a single pulse is 321.57 V. When the pulse interval is 1 μs and the pulse number is 5, the threshold voltage for multiple pulses is 163.42 V, which is reduced by 49.12% compared with a single pulse. These results provide a reference for the damage design of electromagnetic pulse weapons.

Comprehensive cancer therapy protocols are generally administered periodically (at discrete time points) and often determined by tumor size. In the literature, a class of mathematical models are proposed, including therapeutic protocols either with pulse therapy at fixed time points or with state-dependent therapy. However, it is clear in practice (in both clinical and experimental contexts) that the treatment process is much more complex combining pulse surveillance (pulse therapy) with a threshold policy (state-dependent implementation of therapy). Here, we propose a novel mathematical model describing tumor size-guided pulse therapies at fixed time points, which is more in line with the design of clinical protocols for cancer therapies. In studying the dynamics of the proposed model, we find a new kind of periodic solution for dynamical systems with pulse intervention, which we denote as a ( l + m ) T periodic solution. In more detail, the study of the existence and stability of semi-trivial periodic solutions uncovers very rich dynamics, including the existence of order-k effector-free periodic solutions. We obtain analytical expressions for these, and establish the existence of order-1 tumor-free periodic solutions. Furthermore, we discuss the existence and stability of positive periodic solutions. We initially establish the existence of stable order-1 periodic solutions through carefully considering the bifurcation near the effector cell-free periodic solution. Our numerical simulations confirm three possibilities: 1) that two different positive periodic solutions can be bi-stable, 2) that the positive equilibrium can be bi-stable with a positive periodic solution, or 3) that the solution is tri-stable with two different positive periodic solutions. Our main results show that no tumor-free periodic solution exists when the threshold policy is feasible, and this may be a reason why frequently a tumor can be only reduced to a certain low level and not eliminated completely. One of the key considerations in the threshold schedule is to determine an optimal threshold of tumor size to balance the therapy frequency (or the times of therapy) and the amplitude of the tumor size, furthermore the optimal therapy should also be individual-based (or personalized). We believe that our modelling approach can be widely applied into many other fields of life science, and provide critical guidance for the implementation of control strategies.

Bifurcation amplifiers are two-state systems that behave as flip-flops. We propose a two-bit shift register with coupled bidirectional bifurcation amplifiers. We consider a model of the amplifier that is based on a driven nonlinear vibrational system with Duffing nonlinearity. A discussed physical implementation is a nano-mechanical system. The analysis of bifurcation points provides a design framework for driving forces. We use a modulated two-level pulse at the first amplifier and a periodic three-level pulse at the second. We numerically demonstrate that these driving forces allow for the transfer of digital data between each amplifier. Our investigation provides an alternative approach for developing digital shift registers using nonlinear dynamics at the nanoscale.

KHNP had licensed Dynamic Control rod Reactivity Measurement (DCRM) method using detector current signals of PWRs in 2006. The method has been applied to all PWRs in Korea for about 15 years successfully. However, the original method was inapplicable to PWRs using low-sensitivity integral fission chamber as ex-core detectors because of their pulse pile-up and the nonlinearity of the mean-square voltage at low power region. Therefore, to overcome this disadvantage, a modified method, DCRM-EK, was developed using kinetics behavior after equilibrium condition where the pulse counts maintain the maximum value before pulse pile-up. Overall measurement, analysis procedure, and related computer codes were changed slightly to reflect the site test condition. The new method was applied to a total of 15 control rods of 1000 MWe and 1400 MWe PWRs in Korea with worths in the range of 200 pcm–1200 pcm. The results show the average difference of -0.4% and the maximum difference of 7.1% compared to the design values. Therefore, the new DCRM-EK will be applied to PWRs using low sensitivity integral fission chambers, and also can replace the original DCRM when the evaluation fails by big noises present in current or voltage signals of uncompensated/compensated ion chambers.

A theoretical novel model of generalized photo-thermoelasticity and hyperbolic two-temperature theory is studied in this paper. The elastic medium is excited by an external magnetic field and pulsed laser based. The model is established in the context of memory-depended derivative (MDD) when the material is time-dependent. The governing equations describe the interaction processes for isotropic homogeneous hyperbolic thermoelastic medium in one-dimensional (1D) space when the non-Gaussian laser pulse model is applied with time delay. Moreover, The Laplace transforms is used to obtain analytical solutions of the main fields. As such, the medium is loaded when traction is free and shocked thermally with time-dependent. The complete solutions are obtained in Laplace time domain when the invers of Laplace transform are used numerically. Numerical results of the main quantities are discussed graphically with the effect of hyperbolic two-temperature when time-delay parameter is taken into account.

Acoustic levitation is considered one of the most effective noncontact particle manipulation methods, along with aerodynamic, ferromagnetic, and optical levitation techniques. It is not restricted by the material properties of the target. However, existing acoustic levitation techniques have some drawbacks that limit their potential applications. Therefore, in this article, an innovative approach is proposed to manipulate objects more intuitively and freely. By taking advantage of the transition periods between the acoustic pulse trains and electrical driving signals, acoustic traps can be created by switching the acoustic focal spots rapidly. Since the high-energy-density points are not formed simultaneously, the computation of the acoustic field distribution with complicated mutual interference can be eliminated. Therefore, compared to the existing approaches that created acoustic traps by solving pressure distributions using iterative methods, the proposed method simplifies the computation of time delay and makes it possible to be solved even with a microcontroller. In this work, three experiments have been demonstrated successfully to prove the capability of the proposed method including lifting a Styrofoam sphere, transportation of a single target, and suspending two objects. Besides, simulations of the distributions of acoustic pressure, radiation force, and Gor'kov potential were conducted to confirm the presence of acoustic traps in the scenarios of lifting one and two objects. The proposed tactic should be considered effective since the results of the practical experiments and simulations support each other.

Study Subject The research concerns attempts to computerize the foundations of pulse diagnostics of Tibetan medicine. An expert in Tibetan pulse diagnostics can evaluate the functioning of an organism (twelve internal organs and three psychophysiological systems) by feeling the pulse in six palpation points on the radial arteries of both wrists of a patient. Nowadays many physicists make attempts to computerize this method. The paper shows a few tests that are intended to «teach» a pulse diagnostics device to identify the diagnostically relevant characteristics of pulse waves. Objective of the Research This investigation is an attempt to objectify basic characteristics of pulse diagnostics. Though pulse diagnostics has always been a subjective art of an experienced doctor, it may also become part of an objective science due to the physical basis that underlies it. Method The paper presents tests of pulse measurements by a pulse diagnostics device in conditions that create certain predictable responses of an organism to outer stimuli. A group of volunteers were exposed to certain stimuli that can bring about predictable responses of the organism to be detected, processed and analyzed by the pulse diagnostics equipment. Conclusion Experiments of this kind give practical material for the analysis of the pulse waves obtained under special conditions, which provides the development of the software for the pulse diagnostic equipment and confirms that objectifying basic characteristics of pulse diagnostics of Tibetan medicine is possible, though in a limited scope.

A method of reconstructing the original partial discharge (PD) signal to improve the accuracy of PD localization in cross‐linked polyethylene (XLPE) cables is presented here. XLPE cables, extremely sensitive to PDs, are the most popular underground cables in urban grids. The conventional PD localization methods, based on evaluation of the arrival times of PD pulses in the time domain, are negatively affected by the dispersion and attenuation of PD signals propagating in the power cable. A method for the accurate localization of PDs realized through inverse frequency domain modelling (IFDM) is presented here. The method, eliminating the systematic localization error caused by the dispersion and attenuation, significantly improves the localization accuracy. The locations of the PD are identified by comparing peak values of the initial PD signals reconstructed from different extracted pulses. A method for evaluating the propagation constant of the cable is also presented. The efficiency of the accurate localization method was verified by laboratory experiments. Besides, the inherent limitations of the conventional PD localization method for longer cable tests are discussed. The inevitable location error in the conventional methods does not exist in the new method.

In order to improve the gas energy conversion efficiency at the outlet of the pulse detonation combustor, numerical calculation methods were used to study the influence of three different cross-section obstacle structures of square, circle and trapezoid on the distribution characteristics of gas pressure potential energy, kinetic energy and internal energy in a single cycle at the outlet of pulse detonation combustor. The results show that: the expansion of pulse detonation gas mainly includes three stages: primary expansion, secondary expansion, and over-expansion. Gas pressure potential energy, kinetic energy and internal energy increase during the primary and secondary expansion stages, and decrease during the over-expansion stage; Pulse detonation combustor with trapezoidal cross-section obstacle structure has the smallest proportion of gas energy at the outlet of the combustor during the over-expansion stage and the highest proportion during the secondary expansion stage; compared with square and circle cross-section obstacle structures, the gas energy distribution at the outlet of the pulse detonation combustor with trapezoidal cross-section obstacle structure is the easiest for turbomachinery to convert the gas energy.

In this work, a numerical study of the solutions of the parabolic and hyperbolic equations of heat conduction with the same physical parameters is carried out and a comparative analysis of the results obtained is carried out. The mathematical formulation of the problem is discussed. The action of the laser is taken into account through the source function, which was chosen as a double femtosecond laser pulse. In the hyperbolic equation, in contrast to the parabolic one, there is an additional parameter that characterizes the relaxation time of the heat flux. In addition, the source of the hyperbolic equation contains an additional term - the derivative of the power density of the source of the parabolic equation. This means that the temperature of the sample is influenced not only by the power density of the source, but also by the rate of its change. The profiles of the sample temperature at different times and its dynamics at different target depths are shown. The calculations were carried out for different time delays between pulses and for different relaxation parameters.

We describe an ultrafast optics laboratory comprising a mode-locked erbium fiber laser, autocorrelation measurements, and a free-space parallel grating dispersion compensation apparatus. The gain spectrum of Er fiber provides a broad bandwidth capable of supporting sub-100 fs pulses centered near a wavelength of 1550 nm. The fiber laser design used here produces a train of pulses at a repetition rate of 55 MHz with pulse duration as short as 108 fs. The pulse duration is measured with a homebuilt autocorrelator using a simple Michelson interferometer that takes advantage of the two-photon nonlinear response of a common silicon photodiode. To compensate for temporal stretching of the short pulse due to group velocity dispersion in the fiber, an apparatus based on a pair of parallel gratings is used for pulse compression. A detailed part that lists in the supplementary material includes previously owned and common parts used by the telecommunications industry, which helps decrease costs of the laboratory. This provides a cost-effective way to introduce the principles of ultrafast optics to undergraduate laboratories.

We study the existence and stability of standing pulse solutions to a singularly perturbed three-component reaction–diffusion system with one activator and two inhibitors. We apply the MAE (matched asymptotic expansion) method to construct solutions and the SLEP (singular limit eigenvalue problem) method to evaluate their stability. This approach is not just an alternative approach to geometric singular perturbation and the associated Evans function, it also yields two advantages: one is extendability to higher dimensional cases, and the other is that it allows us to obtain more precise information about the behaviors of critical eigenvalues. This implies the existence of codimension-two singularities of drift and Hopf bifurcations for the standing pulse solution. Moreover, it is numerically confirmed that stable standing and traveling breathers emerge around the singularity in a physically acceptable region.

Permeability and porosity are the two most important parameters of rocks for the evaluation and exploitation of oil/gas reservoirs. In this study, a modified pulse‐decay method has been developed to measure both permeability and porosity simultaneously. In the present method, the gas pressure in one chamber is changed (increased or decreased) instantaneously and then maintained constant, while the pressure response changing with time in the other one is monitored. A mathematical model of this procedure has been formulated, and a general analytical solution, including the early‐time and late‐time evolutions, has been obtained. The late‐time solution is presented for postprocessing of experimental data, which leads to the simultaneous measurement of permeability and porosity values of tight rocks. Our measurements agree well with those from the classical pulse‐decay and gas expansion methods. Compared with measuring the permeability and porosity separately, the proposed method can reduce the total test time and ensure the permeability and porosity are measured under the same effective stress condition.

International audience; Many-particle time domain methods are rising alternatives to particle-in-cell (PIC) or frequency methods to simulate the wave–beam interactions in traveling wave tubes (TWTs). We focus on two of those: our Hamiltonian discrete model DIMOHA is compared analytically against the pseudospectral method RUBEUS. Although based on two completely different approaches—the Gel’fand transform for DIMOHA and the telegraphist circuit for RUBEUS—we surprisingly find out that they share perfectly parallel sets of equations and variables. However, we conclude that DIMOHA is more flexible than RUBEUS in terms of pitch tapering and absorbing boundary conditions. It also shows excellent stability for steady-state simulation, allowing us to explain some discrepancies of RUBEUS with experimental results. These come from a standing wave pattern which is detectable in the vicinity of the sever. Finally, DIMOHA is tested for the first time with ultra-short pulses and exhibits excellent agreement with RUBEUS.

Reducing the occurrence of pipe bursts, reducing leakage, and reducing energy consumption are the three main goals in implementing pressure control programs in water distribution networks. Service pressure regulation strategy is an evolved approach that encompasses all goals of pressure management. This paper has investigated this approach in a rural network with hydraulic complexities as a case study so that some parts of the network have excess pressure and other low pressure. A computer code based on the method of characteristics (MOC) has been developed for network hydraulic analysis. The generated code analyzes unsteady flow, pressure-driven demand analysis, and dynamic adjustment of pressure control valves based on the target node. Also, the experimental results of a laboratory network have been applied to validate and calibrate the numerical simulation. In addition, by measuring the flow rate and pressure of the network and the results of the minimum night flow method, three consumption patterns were used to generate pulsed nodal demands. Studies show that creating pressure-management areas by hydraulic analysis by MOC will determine the best control strategies. The mean pressure decreased 54% by applying this strategy. Furthermore, the average fluctuations of pressure reduced from 9.7 meters to 3.5 meters.

A point process model based on a class of Cox processes is developed to analyse precipitation data at a point location. The model is constructed using state-dependent exponential pulses that are governed by an unobserved underlying Markov chain. The mathematical formulation of the model where both the arrival rate of the rain cells and the initial pulse depth are determined by the Markov chain is presented. Second-order properties of the rainfall depth process are derived and utilised in model assessment. A method of moment estimation is employed in model fitting. The proposed model is used to analyse 69 years of sub-hourly rainfall data from Germany and 15 years of English rainfall data. The results of the analysis using variants of the proposed model with fixed pulse lifetime and variable pulse duration are presented. The performance of the proposed model, in reproducing second-moment characteristics of the rainfall, is compared with that of two stochastic models where one has exponential pulses and the other has rectangular pulses. The proposed model is found to capture most of the empirical rainfall properties well and outperform the two alternative models considered in our analysis.

The issue of the amendment of article 7 of the 1945 Constitution in Indonesia has caused an uproar among the public during the COVID 19 pandemic. Although constitutionally amendments can be made as article 37 of the 1945 Constitution, it needs to be seen from three sections, namely: 1. Changing the constitution with careful consideration, not carelessness and self-awareness; 2. Give people the opportunity to express their views before making changes; 3. Protect the rights of individuals or minorities. The results of several survey institutions in Indonesia amendments to the three-term presidential term some Indonesians refused. The purpose of this study is to provide a scientific foundation on the pulse rate of the 1945 Constitution during the current COVID-19 pandemic in Indonesia. The purpose of this study is to provide a scientific foundation on the pulse rate of the 1945 Constitution during the current COVID-19 pandemic in Indonesia. The study uses normative legal methods, using three methods, namely: legal methods, historical methods, and conceptual methods. The recommendation of this study is to provide advice and input to JokPro groups and government support parties in the discourse of the idea of a three-term president related to article 7 of the 1945 Constitution

Pulses are considered to be important crop for ensuring nutritional security in Odisha. Proper estimation of growth rate in production of pulse crops allows for more effective cropping system planning and formulation of the agricultural policy of the state. To capture any abrupt changes and the variation in data in different phases of a long time period, spline regression technique is used as it can fit different models in different segments of the time period as necessary without losing the continuity of the model. The present study deals with the estimation of growth rate of area, yield and production of all rabi pulses in Odisha by using best fit spline regression model. To fit the spline regression model, the entire period of study is divided into different segments based on the scatter plot diagram which is further confirmed by testing the significance of change in coefficient of variation between the consecutive segments by chi square test. The regression model found to be suitable from the study of scatter plot of data are linear, compound, logarithmic, power, quadratic and cubic model. The best fit model is selected on the basis of error assumption test and model fit statistics such as R2, adjusted R2 and Mean Absolute Percentage error (MAPE). The respective selected best fit model is used for the estimation of growth rates of area, yield and production of rabi pulses in Odisha for each segment and the whole period of study. Among the spline regression models, the respective linear spline regression model is found to be best fit for area, yield and production of rabi pulses and are used for growth rate estimation of these variables. It is found that though the growth rate in area and yield of rabi pulses are not significant, the growth rate of production is found to be significant for the whole period of study which shows that the interaction effect of area and yield on production seems to dominate.

Science diplomacy has caught remarkable attention in public policy and academic research over the last fifteen years. However, the concept is plagued by a huge talk–action discrepancy: its public discourse has reached a problematic state of dazzling self-adulation, while it is unclear if and how the actual policies and associated organizations live up to these expectations. The article reconstructs three structural causes to explain the recent hype about science diplomacy. It further encourages actors to organize evaluations that ask whether and how actions of science diplomacy can be valuable. In this regard, a first set of fundamental principles is proposed for setting up an evaluative framework. In conclusion, the article advises science diplomacy actors from democratic states and institutions, from both academic research and public policy, to stop dreaming about soft power influence on authoritarian states and regimes but rather face new geopolitical realities.

The forced oscillations of hair bundle of inner hair cells of auditory nervous system evoked by external force from steady state are related to the fast adaption of hair cells, which are very important for auditory amplification. In the present paper, comprehensive and deep understandings to nonlinear dynamics of forced oscillations are acquired in four aspects. Firstly, the complex dynamics underlying the twitch (fast recoil of displacement X which is fast variable) induced from Case-1 and Case-2 steady states by external pulse force are obtained. With help of vector fields and nullclines, the phase trajectory of forced oscillations is identified to be an evolution process between two equilibrium points corresponding to zero force and pulse force, respectively, and then the twitch is obtained as the behavior running along the nonlinear part of X-nullcline. Especially, twitch observed in experiment are classified into 6 types, which are induced by negative change of force, negative and positive changes of force, and positive change of force, respectively, and further build relationships to three subcases of Case-2 steady state with N-shaped X-nullcline (equilibrium point locates on the left, middle, and right branches of X-nullcline, respectively). Secondly, the experimental observation of fatigue of twitch induced by continual two pulse forces, i.e. the reduced amplitude of the latter twitch when interval between two forces is short, is also explained as a nonlinear behavior beginning from an initial value different from that of the former one. Thirdly, the experimental observation of transition between sustained oscillations and steady state induced by pulse force can be simulated for Case-1 steady state with Z-shaped X-nullcline instead of Case-2, due to that there exists bifurcations with respect to external force for Case-1 while no bifurcations for Case-2. Last, the threshold phenomenon induced by simple pulse stimulation exists for Case-1 steady state rather than Case-2, due to that the upper and lower branches of Z-shaped X-nullcline close to the middle branch exhibit coexisting behaviors of variable X while N-shaped X-nullcline does not. The nonlinear dynamics of forced oscillations are helpful for explanations to the complex experimental observations, which presents potential measures to modulate the functions of twitch such as the fast adaption.

In this paper, estimation is made to investigate the influence of thermal loading due to laser pulse on elastic waves. The material through which the waves are propagating is homogeneous and isotropic in nature. Heat conduction through the media is analyzed by the model proposed by dual-phase-lag theory (DPL). The governing non-dimensional equations are solved by using the approximated harmonic solution. The expression for the field variables is obtained generally and represented graphically for a particular medium.

The deflection of charged particles is an intuitive way to visualize an electromagnetic oscillation of coherent light. Here, we present a real-time ultrafast oscilloscope for time-frozen visualization of a terahertz (THz) optical wave by probing light-driven motion of relativistic electrons. We found the unique condition of subwavelength metal slit waveguide for preserving the distortion-free optical waveform during its propagation. Momentary stamping of the wave, transversely travelling inside a metal slit, on an ultrashort wide electron bunch enables the single-shot recording of an ultrafast optical waveform. As a proof-of-concept experiment, we successfully demonstrated to capture the entire field oscillation of a THz pulse with a sampling rate of 75.7 TS/s. Owing to the use of transversely-wide and longitudinally-short electron bunch and transversely travelling wave, the proposed “single-shot oscilloscope” will open up new avenue for developing the real-time petahertz (PHz) metrology., A travelling wave inside a metal slit can reveal its own waveform by probing deflecting motions of charged particles. Here, a real-time THz oscilloscope was demonstrated by utilizing the relativistic electrons and the subwavelength slit waveguide.

Reaction-diffusion systems have been primary tools for studying pattern formation. A skew-gradient system is well known to encompass a class of activator-inhibitor type reaction-diffusion systems that exhibit localized patterns such as fronts and pulses. While there is a substantial literature for the case of a linear inhibitor equation, the study of nonlinear inhibitor effect is still limited. To fill this research gap, we investigate standing pulse solutions to a skew-gradient system in which both activator and inhibitor reaction terms inherit nonlinear structures. Using a variational approach that involves several nonlocal terms, we establish the existence of standing pulse solutions with a sign change. In addition, we explore some qualitative properties of the standing pulse solutions.

It is established numerically that an area of small delay distances limited by the value Ldel-gr, where the spatialenergy profile of the recorded signal has the shape of a convex asymmetric curve with a maximum shifted toward the beginning of the visibility zone, can be selected when an active-pulse vision system registers signals from a diffusely reflecting underlying surface along inclined lines of sight. The value of Ldel-gr depends on the duration of the illumination and strobe pulses. The value of Ldel-gr for a cooperative object (equipped with retroreflectors) coincides with the value previously set for horizontal observation lines. The widths of the visibility zones for cooperative and diffuse objects increase with an increase in the delay distance, tending toward a certain limiting value depending on the duration of the illumination and strobe pulses. The visibility angle in the vertical plane is determined by the duration of the illumination and strobe pulses and the delay distance and height of the vision system installation when observing on inclined lines of sight.

The concept of the memory-dependent derivative has been found to be more intuitive for understanding the physical meaning of real-world problems. The attractiveness of the memory-dependent derivative can be understood in such a way that its important components can be freely chosen according to the requirements of the problem. Linear viscosity theory plays a critical role in the study of solids and polymers when they are subjected to thermodynamic loading. The current study presents a new mathematical model based on the concept of memory-based derivative to analyze the nature of the thermoviscoelastic micro-beams surrounded by a magnetic field considering the effects of temperature change. The governing equations are constructed in the context of generalized thermoelasticity with two delay times using the concept of Euler-Bernoulli beam theory, Maxwell's electromagnetic equations and the Kelvin-Voigt viscosity model. The proposed model has been applied to study a micro-beam fixed at both ends and exposed to a laser pulse type heat source. The analytic solutions of the physical fields have been determined using the Laplace transform technique. In order to show the efficiency of the new thermal conductivity model, a comparison has been made between the results in the presence or absence of the memory-dependent derivative. In addition, the significant effects of influencing parameters such as memory-dependent derivative, kernel function and time delay as well as the intensity of the laser pulse on the physical fields have been analyzed.

"The sustainable provision of urban forest benefits can be threatened by the occurrence of sudden, major disturbance events, such as forest fires, insect outbreaks, and extreme weather events, which are considered to be “pulse” disturbance events from a socio-ecological systems perspective. Sound urban forestry programs are needed to prepare for these disturbances and reduce their negative impacts. To investigate the role of governance in building more resilient urban forest socio-ecological systems, the relation between pulse disturbances and urban forest governance was studied in 4 Canadian cities. Our study of local urban forestry included expert interviews with local urban forest governance actors, document analysis, and site visits. The Policy Arrangement Approach was applied to structure and analyse urban forest governance. Findings show that all cities had seen a development of their urban forestry programs and governance over time, such as development of staff and formal plans, as well as alliances with key partners. Pulse disturbances seem to have played an important role in the development and sometimes reorientation of urban forestry programs. Although disturbances often had devastating impacts, having a strong urban forestry program in place, including strong alliances with, e.g., industry partners or NGOs, was considered important for handling the aftermath of these events. Efforts had also been made to be better prepared for future disturbances through further professionalization, development of plans, guidelines, and best practices, capacity building through partnerships, and setting up better real-life information systems in support of decision making. Results can inform urban forest governance and urban forestry programs in Canadian cities and elsewhere."

Nonlinear transmission lines (NLTLs) provide a means to generate high-repetition-rate, high-power microwaves with fewer auxiliary systems than conventional sources. They are typically driven by pulse forming networks (PFNs) or Marx generators, and one would intuitively hypothesize that the microwave generation would not depend significantly on the method used to generate the input pulse to the NLTL. This study examines the implications on microwave output by using a Blumlein pulse generator with a 10-ns pulse duration and 1.5-ns rise and fall times to drive coaxial NLTLs produced using composites with nickel zinc ferrite and barium strontium titanate (BST) inclusions. Applying a 30-kV pulse to the composite NLTLs produced frequencies ranging from 1.1 to 1.3 GHz with output powers over 20 kW. The output frequencies increased with increasing volume fraction of BST. Measured results and simulations using LT SPICE showed that Blumlein modulators were insufficient to drive NLTLs to produce high-power oscillations; however, LT SPICE simulations showed that applying a standard PFN to the same NLTL produced the expected oscillations. This difference arises because the mechanism for Blumlein pulse formation cancels the shockwaves responsible for inducing microwave production by the NLTL.

Ultra-short pulse lasers, generating coherent light pulses with pulse durations in the picosecond and femtosecond range, are becoming popular in precision laser microfabrication. They are benefiting not only from well-predicted laser ablation with the suppressed heat-affected zone but also by opening new processing opportunities, especially in transparent materials, due to enhanced non-linear interaction with the material. In this review, the evolution of various kinds of mode-locked lasers from a scientific toy to a robust industrial tool is reviewed. The utilization benefits of high-average-power, high-pulse-repetition-rate ultra-short pulse laser are closely related to beam shaping and manipulation techniques. Fast beam scanning with galvanometric and polygon scanners as well as multi-beam parallel processing methods were developed. Some hot applications areas are briefly described. The efficient use of photons from ultra-short pulse lasers pushed the development of optimization methods in the ablation process. Efforts toward upscaling the process by increasing the average power of mode-locked lasers made feedback to laser developers, and burst regime became a necessity as well as high-speed beam scanning devices. Unique opportunities of ultra-short pulses are successfully exploited in machining transparent materials, with glass separation being the leading application.

Synchronous optimal pulse width modulation is commonly applied when the ratio between the fundamental frequency and the switching frequency is low. The offline computed pulse patterns are optimized in terms of harmonic distortion in the phase currents. Usually, the underlying optimization problem is based on a simple inductor model representing the harmonic behavior of one phase of a nonsalient machine. This paper proposes an alternative formulation of the optimization problem which generalizes it for salient machine types. An investigation of the optimization results’ sensitivity to operating point dependent parameters is presented.

In this paper, the indirect boundary element method (IBEM) is developed to solve the ground motion effect of the near-fault complex site. By establishing a two-dimensional kinematic finite fault model, the amplification effect of seismic response of sedimentary valley under the continuous dislocation of reverse faults is quantitatively analyzed. Meanwhile, the influence of the parameters such as the buried depth of the fault top, the fault dip-angle, the fault distance of sedimentary valley, the fault-plane shape, and the rupture velocity of fault on the seismic response are studied. The results show that the sedimentary valley has a pronounced amplification effect on the seismic response induced by near-fault, and the peak value of the acceleration response spectrum of the analyzed model can be amplified by 99.3%. In the sedimentary valley, the duration of earthquake motion is significantly prolonged, and the long-period velocity pulse appears, and the first velocity pulse can be amplified by 68.7%. The near-fault ground motion damages have typical concentration-effect and hanging wall effect. This study provides a new and effective method, which is of great significance for seismic zoning of complex sites near-fault. It will be of guiding significance for regional planning and seismic fortification of near-fault sites.

A complex of problems related to semi-automatic and automatic underwater wet welding, concerning both equipment and ways of implementation of arc process, has been considered. An analysis of existing developments in the considered field of welding has been carried out, and the most rational designs of semi-automatic machines for welding with flux-cored electrode wire have been revealed. It is shown that the semiautomatic device with a submerged block is the most rational design; the feeding mechanism, placed in the block, has its own additional body, filled with insulating-lubricating liquid, in which the drive motor is submerged. It is noted that a peculiarity of welding-in-fusion in aqueous medium is unpleasant formation of joints on the vertical plane. The most effective ways of improving semi-automatic and automatic machines related to modulated processes and processes with controlled pulse feeding of electrode wire are presented. It is shown that lately the most effective choice of electric motor is its valve design. At the same time, the feeding mechanism in the gearless version is possible. Specially designed computerized control and regulation system is used for realization of semiautomatic machine's work cycle and the chosen algorithm of electrode wire feeding. The results of electrode wire pulse feeding application on properties of welded joints are given. It is determined that characteristics of pulse feeding (frequency, duty cycle) influence geometric characteristics of the weld, as well as strength properties, in particular yield and time resistance limits, which, among other things, is caused by reduction of nonmetallic inclusions in the weld metal and the weld zone. External types of beads welded in aqueous medium on the vertical plane are given, it is obvious that formation when using pulse and modulated modes is significantly better than when conducting electric arc process with conventional feeding of the electrode wire. The ways of further improvement of the equipment for welding in aqueous medium by a wet method are shown. One of the most promising ways to improve technical and technological capabilities of mechanized equipment for welding in aqueous medium is the creation and application of systems with combined influence on the process.

Graphdiyne has an inborn band gap energy, where the minimal band gap is about from 0.46 to 1.22 eV, which shows great potential in ultrafast laser generation. In this work, we fabricate a graphdiyne-decorated microfiber and demonstrate its saturable absorption characteristics experimentally. This device is used as a saturable absorber to generate the conventional soliton and noise-like pulse in an erbium-doped mode-locked fiber laser. The conventional soliton with a spectral bandwidth of 2.45 nm can switch into noise-like pulse with 37.14 nm bandwidth by adjusting the pump power and the polarization controller. For the noise-like pulse, the mode-locked state has excellent stability with 2.17 nJ maximum pulse energy and 283 fs coherent peak duration. This work indicates that graphdiyne could be a remarkable nonlinear photonic device to explore the dynamics of various mode-locked pulses.

This study introduces a conceptually new solvent suppression scheme with adiabatic inversion pulses for 1H-detected multidimensional solid-state NMR (SSNMR) of biomolecules and other systems, which is termed “Solvent suppression of Liquid signal with Adiabatic Pulse” (SLAP). 1H-detected 2D 13C/1H SSNMR data of uniformly 13C- and 15N-labeled GB1 sample using ultra-fast magic angle spinning at a spinning rate of 60 kHz demonstrated that the SLAP scheme showed up to 3.5-fold better solvent suppression performance over a traditional solvent-suppression scheme for SSNMR, MISSISSIPPI (Zhou and Rienstra, J Magn Reson 192:167–172, 2008) with 2/3 of the average RF power.

An electroporator is an instrument used for delivering electrical pulses to a tumor. In this work, an electroporator consisting of three main system blocks, namely High Voltage (HV) source, nanosecond (ns) switching, and pulse generation, was designed, developed, and evaluated to generate high voltage ns pulses to treat tumors. The high-voltage source block was used to convert the 9.6V DC from the battery to a variable HV output and store this charge for later use. The ns switching block contained a MOSFET-based low-side switch which applies short ns pulses to the load. The pulse generation block generates short ns pulses and supplies the adequate current to turn on the MOSFET at a quicker rate aiding the application of these pulses to the load. This process was simulated using PSpice software and the results are presented.

A permanent displacement model (PDM) is often used for hazard assessment of earthquake-induced landslides (ELHA) at regional scale. Pulse-like ground motions (PLGM) are rarely considered in the existing PDMs, although they have been proved to have significant influence on the initiation of landslides in near-fault area. In this paper, taking an area affected by 1994 Mw 6.7 Northridge earthquake as an example, 3 PDMs composed of PLGM, and 11 other models were selected to compare and verify the effects of PLGM. According to the results of multiple evaluation metrics such as the ground failures captured (%GFC), receiver operating characteristics (ROC), and quality sum (Qs), it indicates that the PDMs composed of PLGM use less ground motion records, but the accuracy of evaluation results is higher. This shows that PLGM have significant effect on ELHA. The ELHA method considering the near-fault PLGM was applied to a certain area along the Sichuan-Tibet Railway. The results show that the displacement model considering PLGM predicted more landslides cells. Among them, 8.45% of the slopes are in the extremely high hazard area, and about 30% of the extremely high hazard area is within 5 km of the railway. The slope with high hazard of earthquake-induced landslide can be investigated and protected in advance to avoid casualties and property losses.

We characterize the frequency response of channel-interleaved photonic analog-to-digital converters (CI-PADCs) theoretically and experimentally. The CI-PADC is composed of a photonic frontend for photonic sampling and an electronic backend for quantization. The photonic frontend includes a photonic sampling pulse generator for directly high-speed sampling and an optical time-division demultiplexer (OTDM) for channel demultiplexing. It is found that the frequency response of the CI-PADC is influenced by both the photonic sampling pulses and the OTDM, of which the combined impact can be characterized through demultiplexed pulse trains. First, the frequency response can be divided into multiple frequency intervals and the range of the frequency interval equals the repetition rate of demultiplexed pulse trains. Second, the analog bandwidth of the CI-PADC is determined by the optical spectral bandwidth of demultiplexed pulse trains which is broadened in the OTDM. Further, the effect of the OTDM is essential for enlarging the analog bandwidth of the CI-PADC employing the photonic sampling pulses with a limited optical spectral bandwidth., Comment: 11 pages, 8 figures

This brief presents a low-power counter-based adaptive equalizer that does not require additional power-hungry comparators for an equalizer adaptation loop. A pulse generator in the proposed equalizer obviates the need for additional error sampling comparators. Instead, it allows the receiver to utilize an output of a data decision comparator for the equalizer adaptation by generating a pulse that indicates whether the comparator makes a firm decision for the incoming data. A single comparator is shared by the data recovery path and equalizer adaptation loop. Consequently, the proposed counter-based equalizer achieves a low power dissipation owing to the reduced number of comparators. Fabricated in a 28-nm CMOS technology, the prototype receiver occupies an active area of 0.004 mm2 and consumes only 0.99-pJ/b at 15-Gb/s.