Periodic Excitation Research Articles

Characteristic of temporal light modulation reference meter and standard light source for calibration and verification

Abstract The measurement of the temporal light modulation (TLM) of a light source is gaining increasing importance owing to its detrimental effects on human vision and health. To establish traceability in TLM measurements, the National Institute of Metrology, China (NIM), established a TLM reference meter (TLMM) and standard TLM light source (STLS) for calibration and verification services. The TLMM and STLS employ detector- and source-based approaches, respectively, to define the standards for TLM quantities. The TLMM rapidly acquires light waveform data from the TLM light sources and calculates corresponding TLM quantities. Frequency calibration result is with an expanded uncertainty of 1 × 10−5, frequency response function is almost flat in range of 1 kHz–25 kHz, and response time is less than 8 × 10−6 s. The electrical noise was evaluated at approximately 1000:1–5000:1. The STLS generates an arbitrary TLM waveform by converting the virtual waveform into an actual LED output light waveform. For the frequency response function, the relative amplitude decreased by 1% with a frequency of 15 kHz, and response time was less than 5 × 10−6 s. The linearity of the frequency dependency was studied with ratio varied by approximately 0.19% when the periodic triangle excitation in frequency band from 1 Hz to 1 kHz. Experimental comparisons demonstrated that TLM quantities (frequency, percentage flicker, flicker index, short-term flicker severity P st LM , and stroboscopic effect visibility measure ( SVM )) are consistent between the TLMM and STLS devices on 14 typical TLM waveforms. For P st LM , most of the deviations were in the range of −0.019–0.079 (except for one with 0.182). For SVM , most of the deviations were in the range of −0.001–0.003 (except for one with 0.014).

Utilization of the Resonance Behavior of a Tendon-Driven Continuum Joint for Periodic Natural Motions in Soft Robotics

Continuum joints use structural elastic deformations to enable joint motion, and their intrinsic compliance and inherent mechanical robustness are envisioned for applications in which the robot, the human, and the environment need to be safe during interaction. In particular, the intrinsic compliance makes continuum joints a competitor to soft articulated joints, which require additional integrated spring elements. For soft articulated joints incorporating rigid and soft parts, natural motions have been investigated in robotics research to exploit this energy-efficient motion property for cyclic motions, e.g., locomotion. To the best of the author’s knowledge, there is no robotic system to date that utilizes the natural motion of a continuum joint under periodic excitation. In this paper, the resonant behavior of a tendon-driven continuum joint under periodic excitation of the torsional axis is experimentally investigated in a functional sense. In the experiments, periodic inputs are introduced on the joint side of a tendon driven continuum joint with four tendons. By modulating the pretension of the tendons, both the resonant frequency and the gain can be shifted, from 3 to 4.3 Hz and 2.8 to 1.4, respectively, in the present experimental setup. An application would be the rotation of a humanoid torso, where gait frequencies are synchronized with the resonant frequency of the continuum joint.

Nonlinear analysis of hydrodynamics of a shallow-draft floating wind turbine

AbstractThis study investigates numerically the dynamic responses of the T-Omega Wind novel concept of Floating Offshore Wind Turbine. The turbine is light-weight, has a shallow-draft and a relatively high centre of gravity that allows it to glide over harsh marine environments. The turbine responses are studied under regular wave excitation, considering most probable ranges of discrete sea wave heights and periods representative of real ocean conditions. A multibody virtual model is developed, simplified to a rigid 6 DOF system and experimentally validated in the state-of-art Marine Simulator to define the types of dynamical responses for both “Low” and “High” Sea States. The dynamics of coupled heave and pitch DOFs are evaluated with time histories, phase-plane portraits, Poincaré sections and FFT analyses to conclude that period-1 stable solutions exist for all studied cases of “Low Sea States”, whereas period-2, period-3 and period-4 periodic responses are identified for short wave periods of excitation under “High Sea States” conditions. Simulation results show that regions where period-1 responses exist are highly sensitive to wave height and can widen as the wave amplitude reduces. Finally, the turbines’ nonlinearities generated by the floats’ geometry are observed in this dynamical system, which are identified to be related to variation in float waterplane area and particularly observable for “High Sea States”.

Numerical investigation of the influence of suction surface synthetic jet on the performance of transonic axial flow compressor

In order to investigate the effect of suction surface synthetic jet on the aerodynamic performance of transonic axial compressor, Rotor35 was used for numerical simulation. The results show that at four different positions, the stability margin of the compressor is slightly reduced by suction surface excitation, but there is an optimal position that can improve the compressor total pressure ratio and efficiency. At this position, there is little change in the total pressure ratio at the peak efficiency, and the efficiency is improved by 0.58%. The total pressure ratio and efficiency of the design point are increased by 0.18% and 0.55%, respectively. The periodic excitation of synthetic jet can effectively separate the suction surface and reduce the separation loss, which is the reason for the improvement of compressor efficiency. However, for the transonic compressor, synthetic jet on the suction surface obstructs the radial migration vortex that reaches the tip to the exit, but cause it to gather in the tip channel, resulting in the blockage and reduction of the stability margin of the compressor. In order to take into account the stability margin of the compressor, the coupled flow control is carried out by combining the casing treatment with synthetic jet on the suction surface. The results show that the flow margin of the compressor is increased by 8.76%, the total pressure ratio is increased by 1.76%, and the efficiency is only decreased by 0.13%. In coupled flow control, the suction and injection effects of the casing treatment can make up for the negative influence of synthetic jet on the tip flow, effectively improve the tip flow and expand the stable working range of the compressor. Compared with flow control that only carries out casing treatment, coupled flow control can exert the advantages of synthetic jet suppressing suction surface separation, reduce shock loss, outlet loss and casing treatment loss, and make up for the shortage of excessive efficiency reduction after casing treatment, which is the main reason for the improvement of compressor performance.

Catalytic Impedance Spectroscopy: Concept and Application on CO2 Methanation.

Complex modeling of periodic excitation combined with time-resolved product detection is used to describe the complex response function of a catalytic system. We describe this concept of catalytic impedance spectroscopy (CIS) and the underlying general experimental approach and a concrete setup. The feasibility of CIS is experimentally demonstrated along the catalytic CO2 methanation reaction. The measurements confirm the theoretically anticipated rate-determining step of HCO* → CH* on Ni catalysts. Limitations and prospects of CIS to unravel reaction mechanisms are discussed.

Efficient Transport Controlled by Biharmonic Frictional Driving.

Dry friction has been proposed as a rectifying mechanism allowing mass transport over a vibrating surface, even when vibrations are horizontal and unbiased. It has been suggested that the drift velocity will always saturate when the energy of the input oscillation increases, leading to a vanishing efficiency that would hinder the applicability of this phenomenon. Contrary to this conjecture, in this Letter we experimentally demonstrate that, by carefully controlling the forcing oscillations, this system can maintain a finite transport efficiency for any input energy. A minimal friction model explains the observed dependencies of the drift velocity on the signal parameters in the case of biharmonic base oscillations, which can be extended to obtain efficiency estimates for any periodic excitation.

Influence of separation, collision and friction of rotating ring in sleeve on vibration characteristics of gas face seals

Purpose This study aims to understand how the assembly of rotating ring affects the axial forced vibration of gas face seals. Design/methodology/approach A three-mass kinematic model is established to investigate the axial movement of the rotating ring with bilateral constraints. The separation, collision and frictional sliding of the rotating ring in sleeve are discussed under rotor excitation. The effects of operating parameters and O-ring dynamic characteristics on the separation degree and film thickness disturbance are analyzed. A dimensionless axial characteristic force is defined to determine the critical conditions for the occurrence of separation. Several effective methods to eliminate the separation are proposed based on the adjustment of typical installation parameters. Findings Under rotor excitation, there may be two collisions between the rotating ring and the sleeve surfaces in one excitation period. This will cause self-excited vibration of the fluid film, increasing the risk of seal failure. The separation and collision can be prevented by increasing the equilibrium ratio, the installation radius of the O-ring on the outer surface of the rotating ring and the friction in the sleeve. Originality/value The results develop the modeling of multibody dynamics of gas face seals, enabling more accurate prediction of vibration characteristics.

Grazing-sliding bifurcation in a dry-friction oscillator on a moving belt under periodic excitation.

In this paper, we consider the grazing-sliding bifurcations in a dry-friction oscillator on a moving belt under periodic excitation. The system is a nonlinear piecewise smooth system defined in two zones whose analytical expressions of the solutions are not available. Thus, we obtain conditions of the existence of grazing-sliding orbits numerically by the shooting method. Then, we compute the lower and higher order approximations of the stroboscopic Poincaré map, respectively, near the grazing-sliding bifurcation point by the method of local zero-time discontinuity mapping. The results of computing the bifurcation diagrams obtained by the lower and higher order maps, respectively, are compared with those from direct simulations of the original system. We find that there are big differences between the lower order map and the original system, while the higher order map can effectively reduce such disagreements. By using the higher order map and numerical simulations, we find that the system undergoes very complicated dynamical behaviors near the grazing-sliding bifurcation point, such as period-adding cascades and chaos.

Simulation-based effective comparative analysis of neuron circuits for neuromorphic computation systems

The spiking neural networks (SNN) which are inspired by the human brain offers wider scope for application in the growth of neuromorphic computing systems due to their brain level computational capabilities, reduced power consumption, minimal data movement cost, and among other advantages. Spike-based neurons and synapses are the essential building blocks of SNN, and their efficient implementation is vital to its performance enhancement. In this regard, the design and implementation of spiking neurons have been the major focus among the researchers. In this paper, functioning of different leaky integrate fire (LIF)-based spiking neuron circuits like frequency adaptable CMOS-based LIF, resistor-capacitor-based (RC) LIF, and volatile memristor-based LIF are subjected to comparison. The work mainly focuses on revealing analysis of spike duration and amplitude, number of spikes produced during excitation period, threshold operation, field of application, and various other significant parameters of aforementioned neuron circuits. Extensive simulations of these circuits are carried out utilizing the Cadence Virtuoso simulation environment in order to validate their behavior. Further, a brief comparative analysis is executed considering into account the attributes like circuit complexity, supply voltage, firing rate, membrane capacitance, nature of input/output, refractory mechanism, and energy consumption per spike. This work seeks to assist researchers in selecting an appropriate LIF model to efficiently construct memristors and/or non-memristors based SNN for certain application.

Analysis of the influence of nonlinear energy sink parameters applicable to helicopter main reduction systems

Abstract In response to the vibration problem of helicopter fuselage caused by continuous rotor periodic excitation force, a nonlinear energy sink is considered to be installed on the main reduction transmission channel to reduce the vibration level of the fuselage. This article conducts an analysis of the influence of nonlinear energy sink structure parameters under harmonic excitation force, establishes a coupled dynamic model of helicopter main reduction/absorber/fuselage, and uses harmonic balance method and stability analysis theory to analyze the periodic solution and stability of the system. Using the vibration amplitude of the system as the evaluation criterion, the influence of damping, stiffness, and mass ratio on the vibration suppression effect of the nonlinear energy sink was explored. The results showed that as the damping of the nonlinear energy sink increased, the resonance frequency of the coupled system shifted to the left, and the vibration amplitude of the main reduction system increased; As the stiffness of the nonlinear energy sink increases, the vibration amplitude of the coupled system will first decrease and then increase, gradually approaching the vibration amplitude of the system without coupled dampers; The influence of mass ratio on system amplitude follows the same trend as the influence of stiffness. By optimizing, the structural parameters of the nonlinear absorber with good vibration suppression effect are ultimately obtained.

Hopping potential wells and gait switching in a fish-like robot with a bistable tail

Fish outperform current underwater robots in speed, agility, and efficiency of locomotion, in part due to their flexible appendages that are capable of rich combinations of modes of motion. In fish-like robots, actuating many different modes of oscillation of tails or fins can become a challenge. This paper presents a highly underactuated (with a single actuator) fish-like robot with a bistable tail that features a double-well elastic potential. Oscillations of such a tail depend on the frequency and amplitude of excitation, and tuning the frequency-amplitude can produce controllable oscillations in different modes leading to different gaits of the robot. This robot design is inspired by recent work on underactuated flexible swimming robots driven by a single rotor. The oscillations of the rotor can propel and steer the robot, but saturation of the rotor makes performing long turns challenging. This paper demonstrates that by adding geometric bistability to the flexible tail, turns can be performed by controllably exciting single-well oscillations in the tail, while exciting double-well oscillations of the tail produces average straight-line motion. The findings of this paper go beyond the application to a narrow class of fish-like robots. More broadly we have demonstrated the use of periodic excitation to produce bistable response that generate different gaits including a steering gait. The mechanics demonstrated here show the feasibility of applications to other mobile soft robots.

On a New Cyclic Symmetry Formulation Accounting for Boundaries Undergoing Nonlinear Forces

Abstract Although cyclic symmetry theory was initially developed for linear structures, the introduction of nonlinear forces on internal nodes of the fundamental sector does not affect the methodology. Nevertheless, the method is ill-suited when nonlinear forces are applied at the cyclic boundary. The purpose of this paper is to provide a complement to this theory and to propose a cyclic symmetry formulation for structures undergoing nonlinear forces at their cyclic boundary. A complete nonlinear cyclic formulation for such systems is derived in this work. The advantages of such an approach lies in the reduction of computational costs using the cyclic symmetry properties. The methodology is employed to characterize the dynamics of several mechanical systems. First, it is validated on simplified models of a cyclic system. Two nonlinearities are considered: a one-dimensional friction contact interface and a cubic nonlinearity. Both cases exhibit very different dynamics behaviors, yet, the results obtained with the new strategy are shown to be very accurate. Once the approach is validated, it is employed on a industrial finite element model of turbine bladed disk featuring contact interfaces between the blades' shrouds. The capability of the method to handle large systems is thus demonstrated. For all cases, periodic excitation are applied following either a traveling or standing wave shape for different engines orders.

Coupled tidal tomography and thermal constraints for probing Mars viscosity profile

Computing the tidal deformations of Mars, we explored various Mars spherically symmetric internal structures with different types of interface between the mantle and the liquid core. By assessing their compatibility with a diverse set of geophysical observations we show that despite the very short periods of excitation, tidal deformation is very efficient to constrain Mars interior. We calculated densities and thicknesses for Martian lithosphere, mantle, core–mantle boundary layers and core and found them consistent with preexisting results from other methods. We also estimated new viscosities for these layers. We demonstrated that the geodetic records associated with thermal constraints are very sensitive to the presence of a 2-layered interface on the top of the liquid core in deep Martian mantle. This interface is composed by 2 layers of similar densities but very different viscosity and rheology: the layer on the top of the core is liquid (Newtonian, NBL) and the one at the base of the mantle, overlaying the liquid one, is an Andrade layer (ABL) with a viscosity in average 10 orders of magnitude greater than the Newtonian layer. Our results also indicate that the existence of this 2-layered interface significantly impacts the viscosity profiles of the mantle and the lithosphere. More precisely, models including the 2-layered interface do not display significant viscosity contrast between the mantle and the lithosphere, preventing mechanical decoupling between a lithosphere and the mantle immediately below. Such models are in favor of a stagnant lid regime that can be supported by the current absence of an Earth-like plate tectonics on Mars. Finally, in our results, the presence of liquid Newtonian layer at the top of the liquid core is incompatible with the existence of a solid inner core.

Self-powered piezoelectric sensing system for rotational speed detection of AUV propellers

To realize high-precision self-supplied speed measurement of Autonomous Underwater Vehicle (AUV) propellers, a self-powered piezoelectric speed sensing and detecting system is developed, which consists of a self-powered piezoelectric detection module and energy management and sensing circuits. The system uses three piezoelectric cantilevers for power and sensing detection. The proposed speed detection system is based on the piezoelectric effect and realizes self-powered sensing by utilizing the kinetic energy generated during the rotation of the propeller into electrical energy. The comprehensive model of the proposed piezoelectric sensing system under periodic toggled excitation is established and analyzed. The optimal output power of the system is investigated through theoretical analysis and simulation. The experimental system of the self-powered speed sensing system is constructed and the effect of speed measurement is tested. Experimental results show that the maximum output power of the piezoelectric self-powered sensing system developed in this work is 218 μW, which is much higher than that of the purely triboelectric sensing system. And the average detection error of the self-powered sensing system is 1.4% and the linearity is 1.09% when the propeller speed ranges from 0 to 300 r/min. Compared with similar self-powered systems, the proposed piezoelectric self-powered system is more advantageous in terms of measurement accuracy and can provide more accurate propeller speed measurement.

Periodic Catatonia: A Tangled Spectra within Neuropsychiatry

Catatonia was first described by Kahlbaum in 1874. Subsequently, in 1908, Kraepelin delineated a cyclical pattern of catatonia in a group of patients with Schizophrenia. Further ahead, in 1938, Gjessing demonstrated the role of nitrogen phasic change in synchronous syntonic cases of periodic catatonia. However, Stokes et al., in 1941, demonstrated it to be a result of steady accumulation rather than a phasic change in nitrogen balance. There are no reliable prevalence figures for periodic catatonia. Prominent diagnostic manuals have not given this diagnostic entity a separate nosological status, despite evidence of a discrete metabolic profile. This case series elucidates periodic catatonia in different psychiatric disorders and how a separate diagnostic criterion could help in early detection and management. We narrate three case reports of catatonic manifestations in two young adolescents and one young adult male, with no underlying medical condition. The first case report highlights intermittent brief periods of catatonic excitement beginning with acute anxiety and followed by fainting spells. The second case report narrates an acute onset manic episode which alternates with the catatonic episode. The third case report shows seasonal advents of catatonia. The pharmacological intervention itself was adequate enough to resolve the catatonic symptoms. The three cases give a purview of catatonic manifestations with differential phenomenology. The treatment of catatonia bears challenges owing to a lack of awareness and differential response to available pharmacotherapy.

Near-zero distortion in TCSPC at more than one photon per excitation period: experimental validation.

The time-correlated single-photon counting (TCSPC) technique is widely renowned for its capability of reconstructing rapid and weak light signals with exceptional sensitivity and sub-picosecond timing resolution. Unfortunately, the speed of TCSPC has been historically severely limited to avoid a phenomenon known as pileup distortion. For this reason, the count rate of a classic TCSPC acquisition channel is kept below a few percent of the laser excitation rate (usually 1%-5%). In this work, we experimentally validate a novel, to our knowledge, TCSPC theory recently reported that effectively overcomes such a limitation and finally achieves high-speed operation without distortion. Exploiting a single-photon avalanche diode (SPAD), in this paper we show how to acquire additional information about the status of the system at run time, and by combining it with the classic TCSPC data histogram, we report how a count rate of approximately 60% of the excitation frequency with near-zero distortion can indeed be achieved with a commercial system.

Direct Operando Identification of Reactive Electron Species Driving Photocatalytic Hydrogen Evolution on Metal-Loaded Oxides.

Performing operando spectroscopy under practical reaction conditions and extracting spectral components correlating with reaction activity are crucial in elucidating the reactive species in photocatalysis. However, the observation of weak signals corresponding to reactive photogenerated species is frequently hampered under reaction conditions owing to intense background signals originating from thermally induced species unrelated to the photoinduced reactions. Herein, by synchronizing the millisecond periodic excitations of photocatalysts with a Michelson interferometer used for FT-IR spectroscopy, we succeeded in significantly suppressing the signals derived from thermally excited electrons and observing the reactive photogenerated electrons contributing to the photocatalytic hydrogen evolution. This demonstration was achieved for metal-loaded oxide photocatalysts under steam methane reforming and water splitting conditions. Although it has long been conventionally believed that loaded metal cocatalysts function as sinks for reactive photogenerated electrons and active sites for reduction reactions, we found that the free electrons in the metal cocatalysts were not directly involved in the reduction reaction. Alternatively, the electrons shallowly trapped in the in-gap states of oxides contributed to enhancing the hydrogen evolution rate upon the loading of metal cocatalysts. We verified that the electron abundance in the in-gap states was clearly correlated to the reaction activity, suggesting that metal-induced semiconductor surface states formed in the periphery of the metal cocatalyst play key roles in the photocatalytic hydrogen evolution. Our microscopic insights shift a paradigm on the traditionally believed role of metal cocatalysts in photocatalysis and provide a fundamental basis for rational design of the metal/oxide interfaces as promising platforms for nonthermal hydrogen evolution.

An active-passive integrated actuator based on macro fiber composite for on-orbit micro-vibration isolation

Micro-vibration suppression is crucial for satellites to ensure high imaging performance of optical loads. Herein, an active-passive integrated actuator based on macro fiber composite for micro-vibration isolation is proposed and investigated. Integrated passive and active vibration suppression is achieved by arraying a composite laminated beam consisting of the stiffness layer, damping layer and macro fiber composite layer. A dominant-frequency-correction hysteresis modeling strategy is devised to describe the asymmetric and rate-dependent voltage-force hysteresis of the proposed actuator. By treating the correction as a disturbance, the voltage-force hysteresis is compensated in combination with an extended state observer. In order to achieve resonance suppression, a full-estimation-feedback controller featuring merely displacement response feedback is developed exploiting the estimation of the extended state observer as feedback. Simulation results verify that the full-estimation-feedback controller is capable of suppressing the resonance peak with weak adverse effects on the transmissibility in the isolation band. Finally, experiments are performed to identify the voltage-force hysteresis model and evaluate the vibration isolation performance. Periodic and sweep excitation test results demonstrate that in passive mode, the actuator has a small resonance frequency of 2.3 Hz and a wide isolation band starting from 3.5 Hz. With the full-estimation-feedback controller, the resonance peak is effectively suppressed using a single signal feedback, while maintaining excellent vibration attenuation within the isolation band. The proposed actuator provides a paradigm for the design of active-passive integration vibration isolators for broadband micro-vibration suppression, which holds significant promise in enhancing the effectiveness of current observation missions.

Volatile and Nonvolatile Programmable Iontronic Memristor with Lithium Imbued TiOx for Neuromorphic Computing Applications.

We demonstrate a lithium (Li) imbued TiOx iontronic device that exhibits synapse-like short-term plasticity behavior without requiring a forming process beforehand or a compliance current during switching. A solid-state electrolyte lithium phosphorus oxynitride (LiPON) behaves as the ion source, and the embedding and releasing of Li ions inside the cathodic like TiOx renders volatile conductance responses from the device and offers a natural platform for hardware simulating neuron functionalities. Besides, these devices possess high uniformity and great endurance as no conductive filaments are present. Different short-term pulse-based phenomena, including paired pulse facilitation, post-tetanic potentiation, and spike rate-dependent plasticity, were observed with self-relaxation characteristics. Based on the voltage excitation period, the time scale of the volatile memory can be tuned. Temperature measurement reveals the ion displacement-induced conductance channels become frozen below 220 K. In addition, the volatile analog devices can be configured into nonvolatile memory units with multibit storage capabilities after an electroforming process. Therefore, on the same platform, we can configure volatile units as nonlinear dynamic reservoirs for performing neuromorphic training and the nonvolatile units as the weight storage layer. We proceed to use voice recognition as an example with the tunable time constant relationship and obtain 94.4% accuracy with a minimal training data set. Thus, this iontronic platform can effectively process and update temporal information for reservoir and neuromorphic computing paradigms.

Abstract We100: Altering cardiac impulse propagation and generation by local flash photolysis of caged Ca 2+

Calcium ion (Ca 2+ ) is one of key components in the heart excitation and conduction, and its overload is known to induce abnormal impulse propagation and generation, enabling to lead lethal arrhythmias. However, unknown is how large area of Ca 2+ -overload in a cardiac tissue is required to provoke such abnormalities. By utilizing UV-photolysis of caged Ca 2+ , we investigated whether the increase of Ca 2+ concentration ([Ca 2+ ]) at the local on a cardiomyocytes monolayer alters its spatiotemporal impulse patterns, and also assessed its dependence on area-sizes of the Ca 2+ -overload. The monolayers of cardiomyocytes isolated from neonatal rats were prepared on quartz-substrates (φ27 mm) with 2 days incubation, then treated with a fluorescent indicator of Ca 2+ (Fluo-8/AM: 5 µM) and a caged Ca 2+ (DMNPE-4/AM: 5 - 50 µM). Its excitation manner and impulse propagation were monitored as fluorescence images by a macro-zoom microscope (image size: ~1,500 mm 2 , frame rate: 400 frame/s). Under monitoring, UV light (λ: 365 nm) for flash photolysis of caged Ca 2+ was irradiated to a limited area (diameters of 3 - 9 mm) on the cell layer, with and without electrical pacing. Under periodical excitation by pacing, the delay of impulse propagation was detected at UV-irradiated area on the monolayer. The delay was enhanced with an increase of [Ca 2+ ] under the photolysis, but gradually dissolved with a decay of [Ca 2+ ] after stopping UV irradiation. Under non-pacing, on the other hand, it was found that abnormal impulses were generated from the UV-irradiated area as a result of increase of [Ca 2+ ]. Probabilities about the abnormal impulses showed a linear relationship with the area size of UV-photolysis. Also, we confirmed that the abnormal impulses by the UV-photolysis provoked a reentry-like excitation manner when the electrical conductivity of cardiomyocytes was further degraded by an administration of carbenoxolone. In conclusion, we demonstrated altering impulse propagation/generation of cardiomyocytes monolayer by the local frash photolysis of caged Ca 2+ , and investigated its dependence on spatial conditions of the overload region. The target of this study will be shifted to whole hearts as one on next steps in order to provide the statistical insight in arrhythmogenesis. This research was partially supported by JSPS(18K19459, 22K18174) and JST-CREST(JPMJCR 1925).