Size effect on the static behavior of electrostatically actuated microbeams

We present a new analytical model for electrostatically actuated microbeams to explore the size effect by using the modified couple stress theory and the minimum total potential energy principle. A material length scale parameter is introduced to represent the size-dependent characteristics of microbeams. This model also accounts for the nonlinearities associated with the mid-plane stretching force and the electrostatical force. Numerical analysis for microbeams with clamped-clamped and cantilevered conditions has been performed. It is found that the intensity of size effect is closely associated with the thickness of the microbeam,and smaller beam thickness displays stronger size effect and hence yields smaller deffection and larger pull-in voltage. When the beam thickness is comparable to the material length scale parameter,the size effect is significant and the present theoretical model including the material length scale parameter is adequate for predicting the static behavior of microbeam-based MEMS.

THE AVERAGE AGGREGATE NUMBER OF ELECTROSTATICALLY STABILIZED AGGREGATE(ESAg)

The average aggregate number(N)of electrostatically stabilized aggregate(ESAg)composed of oppositely-charged long-chain molecules,i.e., sodium ω-[α-(nathphyl)ethoxyl]undecanoate(FP^-)and cetyltrimethyl ammonium chloride(CTAC),in aqueous solution at 25℃ has been measured to be 11 to 16 in the CTAC-concentration range of 11×10^(-5) M to 30×10^(-5) M at a fixed FP- concentration of 1.0×10^(-5)M by the photon counting method.

ELECTROSTATICALLY STABILIZED AGGREGATE (ESAg) Ⅱ.EVIDENCE DERIVED FROM THE COAGGREGATING BEHAVIOR OF A CATIONIC KINETIC PROBE (P16^+) WITH SURFACTANTS

The coaggregating behavior of the cationic kinetic probe P16;with different types of surfactants are in complete agreement with predictions based on the newly proposed ESAg concept.

Complete decoupling rebalance loop design of a micromachined electrostatically suspended gyroscope

A micromachined electrostatically suspended gyroscope(MESG)based on UV-LIGA microfabrication process was introduced.By close-loop control,the suspended rotor is kept in null position and through the torque rebalance loop,in which the output control voltages reflects the input angular velocity,a dual-axis input angular velocity can be measured simultaneously.First,the system model of MESG was established by dynamic analysis based on the torque analysis.Then,the rebalance loop under ideal condition is designed using modern control technique.The performance of the designed decoupling rebalance loop was compared with that of conventional proportional integral differential(PID)rebalance loop combined with the compensation loop.In order to realize the decoupling of the output voltages,a compensated decoupling matrix and its difference equation were presented and realized by a digital decoupling method employing digital signal processor(DSP).It was confirmed that the controller could realize the complete decoupling and improve the performance of the gyroscope,which includes merits of fast response speed,low overshoot and good dynamic performance,as the simulation results shown.At last,the circuit and digital realization scheme were given.

Electrostatically Stabilized Aggregate (ESAg). Ⅰ. Evidence Derived from the Coaggregating Behavior of an Anionic Kinetic Probe (P16^-) with Surfactants

A newly proposed ESAg concept is verified by the coaggregation behavior of an anionic kinetic probe （P16;） with various surfactants.

Modeling and Analysis of a Micromotor with an Electrostatically Levitated Rotor

The modeling and evaluation of a prototype rotary micromotor where the annular rotor is supported electrostatically in five degrees of freedom is presented in order to study the behavior of this levitated micromotor and further optimize the device geometry. The analytical torque model is obtained based on the principle of a planar variable-capacitance electrostatic motor while the viscous damping caused by air film between the stator and rotor is derived using laminar Couette flow model. Simulation results of the closed-loop drive motor, based on the developed dynamic model after eliminating mechanical friction torque via electrostatic suspension, are presented. The effects of the high-voltage drive, required for rotation of the rotor, on overload capacity and suspension stiffness of the electrostatic bearing system are also analytically evaluated in an effort to determine allowable drive voltage and attainable rotor speed in operation. The analytical results show that maximum speed of the micromotor is limited mainly by viscous drag torque and stiffness of the bearing system. Therefore, it is expected to operate the device in vacuum so as to increase the rotor speed significantly, especially for those electrostatically levitated micromotors to be used as an angular rate micro-gyroscope.

Axial control for nonlinear resonances of electrostatically actuated nanobeam with graphene sensor

The nonlinear resonance response of an electrostatically actuated nanobeam is studied over the near-half natural frequency with an axial capacitor controller. A graphene sensor deformed by the vibrations of the nanobeam is used to produce the voltage signal. The voltage of the vibration graphene sensor is used as a control signal input to a closed- loop circuit to mitigate the nonlinear vibration of the nanobeam. An axial control force produced by the axial capacitor controller can transform the frequency-amplitude curves from nonlinear to linear. The necessary and sufficient conditions for guaranteeing the system stability and a saddle-node bifurcation are studied. The numerical simulations are conducted for uniform nanobeams. The nonlinear terms of the vibration system can be transformed into linear ones by applying the critical control voltage to the system. The nonlinear vibration phenomena can be avoided, and the vibration amplitude is mitigated evidently with the axial capacitor controller.

Analytical modeling of static behavior of electrostatically actuatednano/micromirrors considering van der Waals forces

In this paper, the effect of van der Waals （vdW） force on the pull-in behavior of electrostatically actuated nano/micromirrors is investigated. First, the minimum po- tential energy principle is utilized to find the equation gov- erning the static behavior of nano/micromirror under electro- static and vdW forces. Then, the stability of static equilib- rium points is analyzed using the energy method. It is found that when there exist two equilibrium points, the smaller one is stable and the larger one is unstable. The effects of dif- ferent design parameters on the mirror＇s pull-in angle and pull-in voltage are studied and it is found that vdW force can considerably reduce the stability limit of the mirror. At the end, the nonlinear equilibrium equation is solved numer- ically and analytically using homotopy perturbation method （HPM）. It is observed that a sixth order perturbation approx- imation can precisely model the mirror＇s behavior. The re- suits of this paper can be used for stable operation design and safe fabrication of torsional nano/micro actuators.

A Study of Super Nonlinear Motion of Electrostatically Coupled Two-Particle System

We consider a pair of nonidentical mechanical pendulums. The bob of each pendulum in addition to its own mass electrically is charged. The pendulums are hung from a common pivot in a vertical plane forming a slanted asymmet-ric ??shaped figure. For arbitrary initial swings that are not necessarily confined to small angles, we analyze the dy-namics of each bob under the influence of gravity’s pull as well as the mutual repulsive Coulombian internal force. The equations describing the motion of the system are a set of highly, supper nonlinear coupled differential equations. Applying Mathematica we solve the equations numerically. For nonidentical parameters describing the pendulums, namely, we show the system behaves chaotically;i.e. the angular position of each pendulum leaves a non-repeatable, chaotic pattern in time. For this coupled two-particle interactive system we show also by folding the time axis, the angular position of one of the pendulums vs. the other traces a Lissajous type curve. Our report includes various traditional phase diagrams and a set of newly designed, useful, phase-type diagrams as well. For a comprehensive understanding about the dynamics of the problem at hand, we provide Mathematica codes conducive to animating the chaotic motion of the system. The generic format of the codes allows adjusting the relevant pa-rameters at will and addressing the “what-if” scenarios.

Triboelectric‘electrostatic tweezers'for manipulating droplets on lubricated slippery surfaces prepared by femtosecond laser processing

The use of‘Electrostatic tweezers'is a promising tool for droplet manipulation,but it faces many limitations in manipulating droplets on superhydrophobic surfaces.Here,we achieve noncontact and multifunctional droplet manipulation on Nepenthes-inspired lubricated slippery surfaces via triboelectric electrostatic tweezers(TETs).The TET manipulation of droplets on a slippery surface has many advantages over electrostatic droplet manipulation on a superhydrophobic surface.The electrostatic field induces the redistribution of the charges inside the neutral droplet,which causes the triboelectric charged rod to drive the droplet to move forward under the electrostatic force.Positively or negatively charged droplets can also be driven by TET based on electrostatic attraction and repulsion.TET enables us to manipulate droplets under diverse conditions,including anti-gravity climb,suspended droplets,corrosive liquids,low-surface-tension liquids(e.g.ethanol with a surface tension of 22.3 mN·m^(-1)),different droplet volumes(from 100 nl to 0.5 ml),passing through narrow slits,sliding over damaged areas,on various solid substrates,and even droplets in an enclosed system.Various droplet-related applications,such as motion guidance,motion switching,droplet-based microreactions,surface cleaning,surface defogging,liquid sorting,and cell labeling,can be easily achieved with TETs.

Electrostatic Interaction-directed Construction of Hierarchical Nanostructured Carbon Composite with Dual Electrical Conductive Networks for Zinc-ion Hybrid Capacitors with Ultrastability

Metal-organic framework(MOF)-derived carbon composites have been considered as the promising materials for energy storage.However,the construction of MOF-based composites with highly controllable mode via the liquid-liquid synthesis method has a great challenge because of the simultaneous heterogeneous nucleation on substrates and the self-nucleation of individual MOF nanocrystals in the liquid phase.Herein,we report a bidirectional electrostatic generated self-assembly strategy to achieve the precisely controlled coatings of single-layer nanoscale MOFs on a range of substrates,including carbon nanotubes(CNTs),graphene oxide(GO),MXene,layered double hydroxides(LDHs),MOFs,and SiO_(2).The obtained MOF-based nanostructured carbon composite exhibits the hierarchical porosity(V_(meso)/V_(micro)∶2.4),ultrahigh N content of 12.4 at.%and"dual electrical conductive networks."The assembled aqueous zinc-ion hybrid capacitor(ZIC)with the prepared nanocarbon composite as a cathode shows a high specific capacitance of 236 F g^(-1)at 0.5 A g^(-1),great rate performance of 98 F g^(-1)at 100 A g^(-1),and especially,an ultralong cycling stability up to 230000 cycles with the capacitance retention of 90.1%.This work develops a repeatable and general method for the controlled construction of MOF coatings on various functional substrates and further fabricates carbon composites for ZICs with ultrastability.

Beamline design for multipurpose muon beams at CSNS EMuS

A new muon beam facility,called the Experimental Muon Source(EMuS),was proposed for construction at the China Spallation Neutron Source(CSNS).The design of the complex muon beamlines for the EMuS baseline scheme,which is based on superconducting solenoids,superferric dipoles and room-temperature magnets,is presented herein.Various muon beams,including surface muons,decay muons and low energy muons,have been developed for multipurpose applications.The optics design and simulation results of the trunk beamline and branch beamlines are presented.With a proton beam power of 25 kW at a standalone target station that consists of a conical graphite target and high-field superconducting solenoids,the muon beam intensity in the trunk beamline varies from 10^(7)/s for surface muons to 10^(10)/s for high-momentum decay muons.And at the endstations,these values vary from 10^(5)/s for surface muons to 10^(8)/s for decay muons.

Accelerating lithium-sulfur battery reaction kinetics and inducing 3D deposition of Li_(2)S using interactions between Fe_(3)Se_(4)and lithium polysulfides

Although lithium-sulfur batteries(LSBs)exhibit high theoretical energy density,their practical application is hindered by poor conductivity of the sulfur cathode,the shuttle effect,and the irreversible deposition of Li_(2)S.To address these issues,a novel composite,using electrospinning technology,consisting of Fe_(3)Se_(4)and porous nitrogen-doped carbon nanofibers was designed for the interlayer of LSBs.The porous carbon nanofiber structure facilitates the transport of ions and electrons,while the Fe_(3)Se_(4)material adsorbs lithium polysulfides(LiPSs)and accelerates its catalytic conversion process.Furthermore,the Fe_(3)Se_(4)material interacts with soluble LiPSs to generate a new polysulfide intermediate,Li_(x)FeS_(y)complex,which changes the electrochemical reaction pathway and facilitates the three-dimensional deposition of Li_(2)S,enhancing the reversibility of LSBs.The designed LSB demonstrates a high specific capacity of1529.6 mA h g^(-1)in the first cycle at 0.2 C.The rate performance is also excellent,maintaining an ultra-high specific capacity of 779.7 mA h g^(-1)at a high rate of 8 C.This investigation explores the mechanism of the interaction between the interlayer and LiPSs,and provides a new strategy to regulate the reaction kinetics and Li_(2)S deposition in LSBs.

Nondestructive and active interrogation system for special nuclear material:proof of principle and initial results

Herein,we employ the threshold energy neutron analysis(TENA)technique to introduce the world's first active interrogation system to detect special nuclear materials(SNMs),including U-235 and Pu-239.The system utilizes a DD neutron generator based on inertial electrostatic confinement(IEC)to interrogate suspicious objects.To detect secondary neutrons produced during fission reactions induced in SNMs,a tensioned metastable fluid detector(TMFD)is employed.The current status of the system's development is reported in this paper,accompanied by the results from experiments conducted to detect 10 g of highly enriched uranium(HEU).Notably,the experimental findings demonstrate a distinct difference in the count rates of measurements with and without HEU.This difference in count rates surpasses two times the standard deviation,indicating a confidence level of more than 96% for identifying the presence of HEU.The paper presents and extensively discusses the proof-of-principle experimental results,along with the system's planned trajectory.

Ion emission from warm dense matter produced by irradiation with a soft x-ray free-electron laser

We report on an experiment performed at the FLASH2 free-electron laser(FEL)aimed at producing warm dense matter via soft x-ray isochoric heating.In the experiment,we focus on study of the ions emitted during the soft x-ray ablation process using time-of-flight electron multipliers and a shifted Maxwell–Boltzmann velocity distribution model.We find that most emitted ions are thermal,but that some impurities chemisorbed on the target surface,such as protons,are accelerated by the electrostatic field created in the plasma by escaped electrons.The morphology of the complex crater structure indicates the presence of several ion groups with varying temperatures.We find that the ion sound velocity is controlled by the ion temperature and show how the ion yield depends on the FEL radiation attenuation length in different materials.

A new electric field mill array with each of the mill’s rotor controlled precisely by a GPS module:Equipment and initial results

We have newly designed an electrostatic sensor,called an electric field mill(EFM),to simplify the estimation of the charge position and charge amount transferred by lightning discharges.It is necessary for this remote estimation of the transferred charge to measure electric field changes caused by charge loss at the time of a lightning strike at multiple locations.For multiple-station measurement of electric field changes,not only speed but also phase for exposure and shielding of the sensing plates inside each EFM of the array should be synchronized to maintain the sensitivities of the deployed instruments.Currently,there is no such EFM with specified speed and phase control performance of the rotary part.Thus,we developed a new EFM in which the rotary mechanism was controlled consistently to within 3%error by a GPS module.Five EFMs had been distributed in the Hokuriku area of Japan during the winter season of 2022-2023 for a test observation.Here we describe the design and a simple calibration method for our new EFM array.Data analysis method based on the assumption of a simple monopole charge structure is also summarized.For validation,locations of assumed point charges were compared with three-dimensional lightning mapping data estimated by radio observations in the MF-HF bands.Initial results indicated the validity to estimate transferred charge amounts and positions of winter cloud-to-ground lightning discharges with our new EFM array.

Gyrokinetic simulations of the kinetic electron effects on the electrostatic instabilities on the ITER baseline scenario

The linear and nonlinear simulations are carried out using the gyrokinetic code NLT for the electrostatic instabilities in the core region of a deuterium plasma based on the International Thermonuclear Experimental Reactor(ITER)baseline scenario.The kinetic electron effects on the linear frequency and nonlinear transport are studied by adopting the adiabatic electron model and the fully drift-kinetic electron model in the NLT code,respectively.The linear simulations focus on the dependence of linear frequency on the plasma parameters,such as the ion and electron temperature gradientsκ_(Ti,e)≡R=L_(Ti,e),the density gradientκ_(n)≡R/L_(n)and the ion-electron temperature ratioτ=T_(e)=T_(i).Here,is the major radius,and T_(e)and T_(i)denote the electron and ion temperatures,respectively.L_(A)=-(δ_(r)lnA)^(-1)is the gradient scale length,with denoting the density,the ion and electron temperatures,respectively.In the kinetic electron model,the ion temperature gradient(ITG)instability and the trapped electron mode(TEM)dominate in the small and large k_(θ)region,respectively,wherek_(θ)is the poloidal wavenumber.The TEMdominant region becomes wider by increasing(decreasing)κ_(T_(e))(κ_(T_(i)))or by decreasingκ_(n).For the nominal parameters of the ITER baseline scenario,the maximum growth rate of dominant ITG instability in the kinetic electron model is about three times larger than that in the adiabatic electron model.The normalized linear frequency depends on the value ofτ,rather than the value of T_(e)or T_(i),in both the adiabatic and kinetic electron models.The nonlinear simulation results show that the ion heat diffusivity in the kinetic electron model is quite a lot larger than that in the adiabatic electron model,the radial structure is finer and the time oscillation is more rapid.In addition,the magnitude of the fluctuated potential at the saturated stage peaks in the ITGdominated region,and contributions from the TEM(dominating in the higher k_(θ)region)to the nonlinear transport can be neglected.In the adiabatic electron model,the zonal radial electric field is found to be mainly driven by the turbulent energy flux,and the contribution of turbulent poloidal Reynolds stress is quite small due to the toroidal shielding effect.However,in the kinetic electron model,the turbulent energy flux is not strong enough to drive the zonal radial electric field in the nonlinear saturated stage.The kinetic electron effects on the mechanism of the turbulence-driven zonal radial electric field should be further investigated.

Effect and mechanism of on-chip electrostatic discharge protection circuit under fast rising time electromagnetic pulse

The electrostatic discharge(ESD)protection circuit widely exists in the input and output ports of CMOS digital circuits,and fast rising time electromagnetic pulse(FREMP)coupled into the device not only interacts with the CMOS circuit,but also acts on the protection circuit.This paper establishes a model of on-chip CMOS electrostatic discharge protection circuit and selects square pulse as the FREMP signals.Based on multiple physical parameter models,it depicts the distribution of the lattice temperature,current density,and electric field intensity inside the device.At the same time,this paper explores the changes of the internal devices in the circuit under the injection of fast rising time electromagnetic pulse and describes the relationship between the damage amplitude threshold and the pulse width.The results show that the ESD protection circuit has potential damage risk,and the injection of FREMP leads to irreversible heat loss inside the circuit.In addition,pulse signals with different attributes will change the damage threshold of the circuit.These results provide an important reference for further evaluation of the influence of electromagnetic environment on the chip,which is helpful to carry out the reliability enhancement research of ESD protection circuit.

Assessment of electrostatic discharge sensitivity of nitrogen-rich heterocyclic energetic compounds and their salts as high energy-density dangerous compounds:A study of structural variables

Nitrogen-rich heterocyclic energetic compounds(NRHECs)and their salts have witnessed widespread synthesis in recent years.The substantial energy-density content within these compounds can lead to potentially dangerous explosive reactions when subjected to external stimuli such as electrical discharge.Therefore,developing a reliable model for predicting their electrostatic discharge sensitivity(ESD)becomes imperative.This study proposes a novel and straightforward model based on the presence of specific groups(-NH_(2) or-NH-,-N=N^(+)-O^(-)and-NNO_(2),-ONO_(2) or-NO_(2))under certain conditions to assess the ESD of NRHECs and their salts,employing interpretable structural parameters.Utilizing a comprehensive dataset comprising 54 ESD measurements of NRHECs and their salts,divided into 49/5 training/test sets,the model achieves promising results.The Root Mean Square Error(RMSE),Mean Absolute Error(MAE),and Maximum Error for the training set are reported as 0.16 J,0.12 J,and 0.5 J,respectively.Notably,the ratios RMSE(training)/RMSE(test),MAE(training)/MAE(test),and Max Error(training)/Max Error(test)are all greater than 1.0,indicating the robust predictive capabilities of the model.The presented model demonstrates its efficacy in providing a reliable assessment of ESD for the targeted NRHECs and their salts,without the need for intricate computer codes or expert involvement.

Hybrid HMX multi-level assembled under the constraint of 2D materials with efficiently reduced sensitivity and optimized thermal stability

The interfacial interaction between HMX molecules and coating materials is the key to the safety performance of explosives and has received extensive attention.However,screening suitable coating agents to enhance the interfacial effect to obtain high-energy and low-sensitivity explosives has long been a major challenge.In this work,HMX-PEI/rGO/g-C_(3)N_(4)(HPrGC)composites were innovatively prepared by a multi-level coating strategy of two-dimensional graphite rGO and g-C_(3)N_(4).The g-C_(3)N_(4) used for desensitization has a richπ-conjugated system and shows outstanding ability in reducing friction sensitivity.The hierarchical structure of HPrGC formed by electrostatic self-assembly andπ-πstacking can effectively dissipate energy accumulation under heat and mechanical stimulation through structural evolution,thus exhibiting a prominent synergistic desensitization effect on HMX.The results show that rGO/gC_(3)N_(4) coating has no effect on the crystal structure and chemical structure of HMX.More importantly,the perfect combination of g-C_(3)N_(4) and rGO endows HPrGC with enhanced thermal stability and ideal mechanical sensitivity(IS:21 J,FS:216 N).Obviously,the new fabrication of HPrGC enriches the variety of desensitizer materials and helps to deepen the understanding of the interaction between explosives and coatings.