Instantaneous Gap Research Articles

Instantaneous gap loss of Sobolev regularity for the 2D incompressible Euler equations

Instantaneous gap loss of Sobolev regularity for the 2D incompressible Euler equations

Application of virtual human sign language translation based on speech recognition

For the application problem of speech recognition to sign language translation, we conducted a study in two parts: improving speech recognition's effectiveness and promoting the application of sign language translation. The mainstream frequency-domain feature has achieved great success in speech recognition. However, it fails to capture the instantaneous gap in speech, and the time-domain feature makes up for this deficiency. In order to combine the advantages of frequency and time domain features, an acoustic architecture with a joint time domain encoder and frequency domain encoder is proposed. A new time-domain feature based on SSM (State-Space-Model) is proposed in the time- domain encoder and encoded using the GRU model. A new model, ConFLASH, is proposed in the frequency domain encoder, which is a lightweight model combining CNN and FLASH (a variant of the Transformer model). It not only reduces the computational complexity of the Transformer model but also effectively integrates the global modeling advantages of the Transformer model and the local modeling advantages of CNN. The Transducer structure is used to decode speech after the encoders are joined. This acoustic model is named GRU-ConFLASH- Transducer. On the self-built dataset and open-source dataset speechocean, it achieves optimal WER (Word Error Rate) of 2.6% and 4.7%. In addition, to better realize the visual application of sign language translation, a 3D virtual human model is designed and developed.

Effects of rotation tool-induced heat and material flow behaviour on friction stir lapped Al/steel joint formation and resultant microstructure

Reliable joining of Al/steel via friction stir lap welding (FSLW) is strongly dependent on interfacial macro-/micro-structures. However, how the underlying thermo-mechanical process affects them and how they can be controlled remain unclear. In this study, a 3D coupled Eulerian–Lagrangian finite element model was integrated with a tracer particle technique to simulate the FSLW of Al alloy 5052 and high-strength DP590 steel, to elucidate the role of tool-induced heat and material flow. The results showed that the material flow recirculated near the shoulder and pin, which mainly originated from the advancing side of the Al and the retreating side of the steel. Increasing the rotational velocity intensified the overall material flow, resulting in increased migration on the steel side. Insufficient steel migration around the pin at lower rotational velocities was mainly responsible for the micro-voids and non-bonding defects at the lap interface. The asynchronous convergence of Al and steel flowing from the advancing and retreating sides, respectively, refilled the instantaneous gap, thereby normally bonding the lapped interface behind the pin. The rotational pin affected the hook structure and steel fragment formation through the shearing and squeezing of the steel migration flow. Material inter-migration produced an intercalated structure at the lapped Al/steel interface. The extremely high temperature, approximately above Al 5052 solidus temperature, under the pin bottom caused the formation of a thicker intermetallic compound (IMC), thereby considerably reducing the interfacial strength. Multi-scale mechanical strength assessments indicated that an intercalated interfacial structure with a thickness of Al-rich IMC layer less than ∼1.0 μm was desirable because it exhibited a higher local interfacial strength than the Al matrix.

Neural Network for Surface-Profile Estimation of Atomic Force Microscope

This paper describes a methodology for implementing an identification algorithm for an atomic force microscope to estimate a surface profile of a sample. A microbeam of the atomic force microscope is modeled as an Euler-Bernoulli beam. A tip-sample interaction force used here is a piecewise function described by the attractive van der Waals force and the repulsive Derjaguin-Muller-Toporov force which can represent the indentation made by a tip of the microbeam into the sample surface. The identification of the instantaneous gap between the tip of the undeformed microbeam and the sample surface is implemented on line based on a trained input-output recurrent network. With the measured cantilevered-beam-tip motion supplied to the recurrent network, the recurrent network is going to compute the estimated gap. The approach being used in this study is in contrast to the conventional approach in that it is based on the signal in the time domain instead of in the frequency domain; therefore, the number of steps involved is fewer. When comparing the proposed approach with the adaptive-tracking controllers based on adaptive control Lyapunov functions, the proposed approach outperforms the adaptive-tracking controllers significantly. Whereas the adaptive-tracking controllers require much more measured signals to supply to the controllers and the parameter estimator. Instead, the proposed approach has to store two units in the tapped-delay-line memory while the identification algorithm is running.

Microscopic Picture of the Solvent Reorganization During Electron Transfer to Flavin in Water.

The redox potential of molecular species is largely modulated by its molecular environment so that a change of the environment will lead to a different redox potential. However, a detailed molecular picture of reorganization of the environment upon reduction is still unclear. To unravel the details of the solvent reorganization during electron transfer, we have performed density functional theory-based molecular dynamics (DFT-MD) and hybrid quantum mechanics/molecular mechanics (QM/MM) simulations of the reduction of lumiflavin. Previously, we have calculated the reduction free energy curves of the redox half reactions of lumiflavin in water as a function of the instantaneous gap energy (ΔE) ( J. Chem. Theory Comput. 2013 , 9 , 3889 - 3899 ). In this work, we focus on finding the changes in the solvent environment that correlate with this ΔE reaction coordinate. Comparing the QM/MM simulations, in which the solvent is modeled with an empirical force field, with the (full) DFT-MD simulations, we find that the response through electronic polarization plays a significant role in the latter case. Also a small charge transfer between flavin and solvent is observed in the full DFT treatment. As a result, we find only in the case of the QM/MM model a strong correlation between ΔE and the (pairwise computed) electrostatic potential (ESP) at the flavin due to the solvent. By analyzing the contribution of the ESP at the flavin per solvent molecule, we cannot only distinguish between the different modes of hydration by solvent molecules that coordinate at the hydrophilic and hydrophobic sides of the flavin molecule but also quantify their contribution to the reorganization free energy by measuring the ESP fluctuations per solvent molecule.

The study on limited asynchronous breaking based on the adjustment of breaking time

Multi-interrupter in series is the only way for high voltage circuit breaker to develop Ultra high voltage levels. It is especially important for multi-interrupter in series to keep synchronization in breaking, but synchronous breaking of multi-interrupter is relative, and asynchronous breaking is absolute, so the conception of limited asynchronous breaking is brought up in this paper. Research on the compensation of dynamic dielectric recovery based on active asynchronous, and make each vacuum circuit breaker (VCB) has a different instantaneous gap length at current zero-crossing, to realize active compensation for dynamic dielectric recovery. In this paper, the model of post arc resistance will be established by ATP DRAW within the research of VCB with triple-interrupters as background, research the limited asynchronous breaking and the dynamic dielectric recovery characteristics of the various interrupter by adjusting the breaking time of the VCB, and the gain analysis of insulation breakdown voltage is analyzed. At last, the module of double-break VCB is established, and the correctness of simulation results is proved by tests.

New Robust Energy Management Model for Interconnected Power Networks Using Petri Nets Approach

The problematic of energy management, particularly in terms of resources control and efficiency, has become in the space of a few years an eminently strategic subject. Its implementation is both complex and exciting as the prospects are promising, especially in relation with smart grids technologies. The deregulation of the electricity market, the high cost of storage, and the new laws on energy transition incite some significant users (collectivities, cities, regions, etc.) to form themselves into local producers in order to gain autonomy and reduce their energy bills. Thus, they may have their own sources (classic and/or renewable energy sources) to satisfy their needs and sell their excess production instead of storing it. In this idea, the territorial interconnection principle offers several advantages (energy efficiency, environmental protection, better economic balance). The main challenge of such systems is to ensure good energy management. Therefore, power distribution strategy must be implemented by matching the supply and the demand. Such systems have to be financially viable and environmentally sustainable. This allows among others to reduce the electricity bill and limit the systematic use of the national power network, typically using non-renewable sources, and thereby support sustainable development. This paper presents an original model for aid-decision in terms of grid configurations and control powers exchanged between interconnected territories. The model is based on Petri nets. Therefore, an iterative algorithm for power flow management is based on instantaneous gap between the production capability (photovoltaic, wind) and the demand of each user. So, in order to validate our model, we selected three French regions: the PACA region, the Champagne-Ardenne region and the Lorraine region. Due to their policy, their geographical and climatic features, we opted for two renewable sources: “wind” and “photovoltaic”. The numerical simulations are performed using the instantaneous productions of each region and their energy demand for a typical summer day. A detailed economic analysis is performed for two scenarios (with or without interconnections). The results show that the use of renewable energy in an interconnection context (i.e. pooling), offers serious economic and technical advantages.

Harmonic reduction in capacitive micromachined ultrasonic transducers by gap feedback linearization

The nonlinear relationship between the electrical input signal and electrostatic force acting on the capacitive micromachined ultrasonic transducer (CMUT) membrane limits its harmonic imaging performance. Several input shaping methods were proposed to compensate for the nonlinearity originating from the electrostatic force's dependence on the square of the applied voltage. Here, we analyze harmonic generation in CMUTs with a time-domain model. The model explains the basis of the input shaping methods and suggests that the nonlinearity resulting from gap dependence of the electrostatic force is also significant. It also suggests that the harmonic distortion in the output pressure can be eliminated by subharmonic ac-only excitation of the CMUT in addition to scaling the input voltage with the instantaneous gap. This gap feedback configuration can be approximated by the simple addition of a series impedance to the CMUT capacitance. We analyze several types of series impedance feedback topologies for gap feedback linearization. We show that for subharmonic ac excitation, although resistive and capacitive impedances result in a trade-off between input voltage and harmonic distortion for a desired pressure output, harmonic generation can be suppressed while increasing the Pa/V transmit sensitivity for proper series inductance and resistance feedback. We experimentally demonstrate the feedback method by reducing harmonic generation by 10 dB for the same output pressure at the fundamental frequency by using a simple series resistor feedback with a CMUT operating at a center frequency of 3 MHz. The proposed methods also allow for utilization of the full CMUT gap for transmit operation and, hence, should be useful in high-intensity ultrasonic applications in addition to harmonic imaging.

Modeling highway-traffic headway distributions using superstatistics

We study traffic clearance distributions (i.e., the instantaneous gap between successive vehicles) and time-headway distributions by applying the Beck and Cohen superstatistics. We model the transition from free phase to congested phase with the increase of vehicle density as a transition from the Poisson statistics to that of the random-matrix theory. We derive an analytic expression for the spacing distributions that interpolates from the Poisson distribution and Wigner's surmise and apply it to the distributions of the net distance and time gaps among the succeeding cars at different densities of traffic flow. The obtained distribution fits the experimental results for single-vehicle data of the Dutch freeway A9 and the German freeway A5.

Expression and regulation of connexins in cultured ventricular myocytes isolated from adult rat hearts.

Gap junctions were assayed during re-differentiation of adult rat cardiomyocytes in long-term culture to gain insight into the processes of remodeling. Double immunostaining allowed the localization of connexins Cx40, Cx43, and Cx45 between myocytes and demonstrated co-expression and co-localization in individual cells and gap junction plaques, respectively. Immunoblots showed differential time-dependent changes in connexin expression and phosphorylation. The total amount of connexins and the ratio of phosphorylated/non-phosphorylated isoforms gradually increased during the re-establishment of intercellular communication. Dual voltage-clamp studies showed the involvement of several types of gap junction channels. Multichannel currents yielded diverse spectra of g(j,inst)=f( V(j)) and g(j,ss)=f( V(j)) relationships ( g(j,inst): instantaneous gap junction conductance; g(j,ss): conductance at steady state; V(j): transjunctional voltage), indicative of homotypic and heterotypic channels. Single-channel currents revealed two prominent conductances reflecting gamma(j,main) and gamma(j,residual). The histograms of gamma(j,main) showed four discrete peaks (41-44, 59-61, 70-76, and 100-107 pS) attributable to a combination of Cx45-Cx45, Cx40-Cx45 and Cx43-Cx45 channels (1st peak), Cx43-Cx43 and Cx40-Cx43 channels (2nd peak), Cx43-Cx43 channels (3rd peak) and Cx40-Cx40 and Cx40-Cx43 channels (4th peak). However, the presence of heteromeric channels cannot be excluded. The data are consistent with an up-regulation of Cx45 and Cx43 during re-differentiation.

Computer Aided Optimization of Bearing and Sealing Gaps in Hydrostatic Machines—The Simulation Tool Caspar

AbstractThe simulation tool CASPAR (Calculation of swash plate type axial piston pump and motor) is presented in this paper. Based on the simulation of the flow through the lubricating gaps in swash plate type axial piston machines the pressure, velocity and temperature fields in the considered gaps can be determined. This allows the calculation of the main losses generated in the machine due to viscous friction and gap flow. The individual gaps are connected in a complex way to each other. The calculation of the gap flow requires the determination of the instantaneous gap heights for all considered gaps. This is realized by solving the motion equation for all moveable parts of the rotating group. For determination of pressure dependent external forces the instantaneous pressure in the displacement chamber is calculated simultaneously. The program further calculates the instantaneous inlet and outlet flow of the swash plate machine for pumping and motoring mode as well as internal volumetric losses.

Electrophysiological properties of gap junction channels in hepatocytes isolated from connexin32-deficient and wild-type mice.

Hepatocytes were isolated from wild-type and connexin32-deficient (Cx32-deficient) mice. Pairs of cells were chosen to study the electrical properties of gap junction channels using the dual voltage-clamp method. The total gap junction currents revealed that Cx32-deficient hepatocytes express one type of connexin (Cx26) and wild-type hepatocytes express two types of connexins (Cx26 and Cx32). The unitary gap junction currents suggest that Cx32-deficient cells have homotypic channels (Cx26-Cx26) while wild-type cells form homotypic (Cx26-Cx26, Cx32-Cx32) and heterotypic channels (Cx26-Cx32). Homotypic channels exhibited a main conductance and a residual conductance, both virtually insensitive to gap junction voltage (Vj) (Cx32-Cx32: gammaj,main=31 pS, gammaj,residual=9 pS; Cx26-Cx26: gammaj,main=102 pS, gammaj,residual=17 pS). Residual states were regularly seen in Cx32-Cx32 channels, but rarely in Cx26-Cx26 channels. Heterotypic channels showed a main conductance and a residual conductance. The former was sensitive to Vj (average gammaj,main=52 pS). The electrophysiological data suggest that Cx32 hemichannels are more abundant than Cx26 hemichannels in prenatal (ratio 4:1) and adult wild-type hepatocytes (ratio 23:1) and that the total number of gap junction channels is larger in prenatal cells than in adult cells. The diversity of the relationship gj, ss/gj,inst=f(Vj) (gj,ss: gap junction conductance at steady state; gj,inst: instantaneous gap junction conductance; Vj: transjunctional voltage) seen in wild-type cells suggests that the ratio Cx26/Cx32 hemichannels is variable among hepatocytes. A comparison of total and unitary conductances implies that Cx26 hemichannels are down-regulated in Cx32-deficient cells and that docking between Cx26 and Cx32 hemichannels occurs randomly. While the gap junction currents are compatible with homotypic and heterotypic channels, the presence of heteromeric channels cannot be excluded.

The performance of an electrorheological fluid in dynamic squeeze flow under constant voltage and constant field

This paper is concerned with an experimental investigation in which an electrorheological (ER) fluid is applied to control vibration. The fluid is sandwiched between two planar electrodes, the upper one fixed while the lower one is subjected to an oscillatory sinusoidal motion and is energized either by a constant voltage or by a constant field. In this dynamic squeeze flow it is seen that the force transmitted across the fluid is greater when the applied electrical field is maintained at a constant level, controlled with reference to the instantaneous gap between the electrodes. In addition, we compare the experimental results with those from an existing theoretical model in which the fluid is assumed to have a bi-viscous rheological characteristic.

Gap junction currents in cultured muscle cells from human myometrium

Objective: The electrophysiologic properties of gap junctions between human myometrial smooth muscle cells were studied. Study Design: Double whole-cell patch clamp recordings were made on pairs of cells from primary cultures of myometrial cells from women undergoing cesarean section. Macroscopic gap junction currents were measured as the change in current in a cell held at a constant voltage while the other member of a pair was subjected to a test pulse of voltage. The blockade by halothane was examined. Results: Mean junctional conductance between pairs of cells was 23 ± 14 nanosiemens ( n = 57). Instantaneous gap junction conductance was constant as a function of transjunctional voltage. For transjunctional voltages of ≤50 mV, currents were constant during a 5-second test pulse. For larger voltages, however, the currents showed a time-dependent decay. The currents were blocked completely and reversibly with 3.5 mmol/L halothane. Single-channel conductances of 60 picosiemens and 15 picosiemens were observed. Conclusion: This first study of gap junction currents in human myometrial cells confirms that connexin43 is the major functional constituent. Functional studies of myometrial gap junction channels may suggest new strategies for controlling uterine contractility. (Am J Obstet Gynecol 1998;178:588-93.)

ワイヤ電極振動に及ぼす単発放電衝撃力の影響

This paper describes the behavior of wire vibration during continuous machining with respect to the action of impulse based on a single discharge. The impulsive force acting on a wire is given by an experimental result of transient wave forms caused by a single discharge with the consideration of the simulation result supposing a vibration system to be a beam. The mean displacement of the wire obtained from the observation of continuous machining does not always obey the resultant displacement calculated by superposition of impulses from a set of single discharges. The vibration model is studied using a nonlinear model in which the number of impulses acting on the wire depends on the instantaneous gap distance between the wire and the workpiece. Thus, the behavior of the wire is significantly affected by the amplitude of the wire due to its tension or machining feed rate and by the discharge interval.

Particle-hopping models of vehicular traffic: Distributions of distance headways and distance between jams

We calculate the distribution of the distance headways (i.e., the instantaneous gap between successive vehicles) as well as the distribution of instantaneous distance between successive jams in the Nagel-Schreckenberg (NS) model of vehicular traffic. When the maximum allowed speed, V max , of the vehicles is larger than unity, over an intermediate range of densities of vehicles, our Monte Carlo (MC) data for the distance headway distribution exhibit two peaks, which indicate the coexistence of “free-flowing” traffic and traffic jams. Our analytical arguments clearly rule out the possibility of occurrence of more than one peak in the distribution of distance headways in the NS model when V max =1 as well as in the asymmetric simple exclusion process. Modifying and extending an earlier analytical approach for the NS model with V max =1, and introducing a novel transfer matrix technique, we also calculate the exact analytical expression for the distribution of distance between the jams in this model; the corresponding distributions for V max > 1 have been computed numerically through MC simulation.

Characterization Of Rotating Flexible Disks Using A Laser Doppler Vibrometer

The dynamics of a flexible disk rotating near a rigid flat plate are characterized experimentally using a laser Doppler vibrometer. The goal of the investigation was to determine the mechanism by which the gap between the disk and the base plate varies with time. A periodic averaging scheme is used to separate the instantaneous gap signal into a periodic component phased to the rotational position of the disk and an independent random component. The periodic component is shown to dominate, demonstrating that the gap variation is caused by permanent deformations of the disk moving past a fixed point. The base plate stabilizes the disk by flattening the deformations, and the gap variations can be further reduced by increasing disk rotational speed. Disks having 100 and 180 Am thickness were investigated; the thicker disks are shown to have less residual curl. The stabilizing influence of the base plate is lost as the hub height is increased, which implies that hydrodynamic forces are essential to the stabilization mechanism. The mean disk shape is generally a linear function of radius; no self-regulating region was observed.

The current and voltage relationships of a stable d.c. arc between copper and silver electrodes in air at 1–760 mm Hg

The paper describes a method that has been developed for measuring the current and voltage characteristics of a stable d.c. arc. The arc is formed between stationary electrodes by first breaking down the gap using a high-voltage capacitor discharge. This discharge is allowed to develop into a power arc which is then maintained by an accumulator supply. The arc current and voltage are measured on peak voltmeters which are switched into the circuit only after the arc has become stable. Switching is done automatically by a sequence controller which also opens the main circuit-breaker as soon as the measurements have been made. In this way, electrode wear is reduced.The methods of previous workers using oscillographic-fllm techniques are reviewed critically; the advantages of the new method of measurement are great saving in time and labour, increased accuracy due to the measurement of true stable arc characteristics, and freedom from the complication of moving electrodes such as is involved in the measurement of instantaneous gap length.This research is part of a general programme of investigation of the effects of reduced gas pressure on the behaviour of an arc. The paper gives the results for copper electrodes in air in the pressure range 4–760mm Hg at currents between 1 and 17 amp and for gaps up to 2mm in length; and for fine silver electrodes in air at pressures of 1–760mm Hg, at currents between 1 and 20 amp for gaps up to 2 in length.The investigation shows that, as the pressure is reduced below approximately 50mm Hg, the difficulties of interrupting a current appear rapidly. At lower pressures the voltage drop in the arc column becomes small compared with the drops at the electrodes, so that it is then possible to maintain an arc at a voltage very little in excess of the minimum arcing value for the electrodes. Under these conditions the length of the gap becomes unimportant, so that lengthening the gap is ineffective as a means of increasing the current-rupturing capacity of a pair of contacts.The experimental results for each electrode material are given in the form of a single expression, which is presented also as a nomograph.