The use of microprocessors in protective systems makes it possible to extract additional information on the power factor or time constant from controlled parameters (current, voltage, power). This ...allows one to increase the capabilities of the protective system significantly, and the efficiency of new improved systems of protection mainly depends on how quickly additional parameters can be determined. It is shown that it is possible to rapidly (in the first 20 ms after the appearance of a current disturbance) determine a power factor by means of analysis of the behavior of the overall instantaneous power in a three-phase circuit. The obtained information allows one to do without data on the starting currents of electromotors and, thus, to increase substantially the protective system’s sensitivity to low short-circuit currents. As a result, protection of “remote backup,” as well as protection from remote short-circuit currents, can be carried out. It is shown that quick determination of the time constant at which an asynchronous motor is started (before rotor rotation) allows one to control the change in the winding resistance and, hence, winding temperature using the behavior of the instantaneous power. This allows one to use the windings themselves as temperature sensors to produce effective thermal protection of electromotors operating in a heavy intermittent regime.
Voltage coupling via linear resistor is effective to realize synchronization between chaotic circuits. While electrical and chemical synapses are often used to connect neurons for reaching ...synchronization. Indeed, synchronization can be stabilized between some no-coupling oscillators driven by noise. In this paper, the potential mechanism of synchronization approach between some initial-dependent oscillators is explored in case of noise. It is found that noise disturbance on the memristive variable can induce distinct changes in the dynamics and the attraction basin of the memristive oscillators and physical motor. Furthermore, with increase of the noise intensity, two memristive nonlinear oscillators can be synchronized completely and the transient period for reaching synchronization is dependent on the involvement of memory term −kxi2xj, which has variable-dependent parameter −kxi2. In fact, noise disturbance can enhance the dynamics dependence of system on the initial setting thus the realization of synchronization becomes easy-going even when no coupling is applied.
•Noise effect and attraction basin in a memrisitve dynamical system are calculated.•Noise driving can enhance the sensitivity and dependence of dynamics on initials.•Synchronization mechanism for noise disturbance is explained.
Background
The use of external fixators to treat foot and ankle deformities remains a challenge in orthopedic surgery due to their diversity. We hope to improve the automation and accuracy of the ...correction process.
Methods
A three‐degree‐of‐freedom (3‐DOF) electromotor‐driven external fixator for uniplanar foot and ankle deformities was proposed. Computer‐assisted correction software was developed to help surgeons use digital technology to measure the required parameters from patients' X‐ray radiographs. The correction trajectory and the prescriptions were generated in the software based on the proposed correction strategy.
Results
Two clinical cases were simulated to verify the correction ability of the developed external fixator. The results showed that the angular and displacement deformities were well corrected.
Conclusions
The developed external fixator can accurately and automatically correct foot and ankle deformities with the help of computer‐assisted correction software, which significantly reduces the burden on surgeons and patients.
The combined radial-axial magnetic bearing (CRAMB) with permanent magnet (PM) providing bias magnetic flux is designed for magnetically suspended high-speed electromotor in the compressor for its ...compact construction. In this paper, the design principle and the initial model of CRAMB are introduced. To improve the performances of CRAMB and better meet the engineering requirements, the optimization is conducted on the bearing. Considering the incompatible objectives of the optimization model, the method of multiobjective optimization (MOO) on the bearing is proposed, which can balance these objectives compared with single-objective optimization (SOO). The objectives and constraints are provided in the form of analytical expressions by means of equivalent magnetic circuit whose rationality is demonstrated by finite-element method (FEM). To optimize the bearing efficiently, the integrated optimum methodology is adopted. After MOO process, the synthetical performances are improved, which are verified by FEM and experiment.
During interactive communication, animals occasionally cease producing communication signals. The behavioral significance of resumed communication signals following a cessation, or silent pause, has ...been described in human speech: word recognition by listeners is enhanced after silent pauses, and speakers tend to place such pauses prior to words that are contextually unpredictable and that therefore have high information content.1–5 How central nervous systems process signals following pauses differently from signals during continuous communication has not been studied at a cellular level. Here we studied behavioral and neurophysiological impacts of pauses during electric communication in mormyrid fish. We found that isolated fish produced fewer and shorter pauses than fish housed in pairs, and that fish tended to produce burst displays immediately following pauses. In the electrosensory pathway, sensitivity to pauses first arose in the midbrain posterior exterolateral nucleus (ELp): evoked field potentials were enhanced as pause duration increased, with a time constant of ∼1 s. Intracellular recording from single ELp neurons suggested that this increased sensitivity resulted from a pause-associated recovery from synaptic depression that was induced by the preceding stimulation. Behavioral responses were also facilitated by longer pauses, with a similar time constant of ∼1 s. Further, during natural electric communication between pairs of fish, the insertion of artificial pauses resulted in increased signaling by the receiving fish immediately following the pause. Thus, our results suggest that pauses during communication release sensory circuits from synaptic depression, thereby maximizing the physiological and behavioral effects of subsequent communication signals.
•During communication, electric fish occasionally pause electric signal production•Pauses allow sensory neurons to recover from short-term synaptic depression•Pauses allow receiving fish to recover from behavioral habituation•Pauses increase sensitivity to communication signals that follow the pause
Kohashi et al. show that electric fish occasionally pause signal production during communication. Pauses allow sensory neurons to recover from short-term synaptic depression, which is associated with recovery from behavioral habituation. Pauses may be an adaptation to increase sensitivity in receivers and maximize the impact of subsequent signals.
The activity of central pattern-generating networks (CPGs) may change under the control exerted by various neurotransmitters and modulators to adapt its behavioral outputs to different environmental ...demands. Although the mechanisms underlying this control have been well established in invertebrates, most of their synaptic and cellular bases are not yet well understood in vertebrates.
, a pulse-type gymnotiform electric fish, provides a well-suited vertebrate model to investigate these mechanisms.
emits rhythmic and stereotyped electric organ discharges (EODs), which function in both perception and communication, under the command of an electromotor CPG. This nucleus is composed of electrotonically coupled intrinsic pacemaker cells, which pace the rhythm, and bulbospinal projecting relay cells that contribute to organize the pattern of the muscle-derived effector activation that produce the EOD. Descending influences target CPG neurons to produce adaptive behavioral electromotor responses to different environmental challenges. We used electrophysiological and pharmacological techniques in brainstem slices of
to investigate the underpinnings of the fast transmitter control of its electromotor CPG. We demonstrate that pacemaker, but not relay cells, are endowed with ionotropic and metabotropic glutamate receptor subtypes. We also show that glutamatergic control of the CPG likely involves two types of synapses contacting pacemaker cells, one type containing both α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and
-methyl-d-aspartate (NMDA) receptors and the other one only-NMDA receptor. Fast neurotransmitter control of vertebrate CPGs seems to exploit the kinetics of the involved postsynaptic receptors to command different behavioral outputs. The prospect of common neural designs to control CPG activity in vertebrates is discussed.
Underpinnings of neuromodulation of central pattern-generating networks (CPG) have been well characterized in many species. The effects of fast neurotransmitter systems remain, however, poorly understood. This research uses in vitro electrophysiological and pharmacological techniques to show that the neurotransmitter control of a vertebrate CPG in gymnotiform fish involves the convergence of only-NMDA and AMPA-NMDA glutamatergic synapses onto neurons that pace the rhythm. These inputs may organize different behavioral outputs according to their distinct functional properties.
Transmission with cardan joints and nonlinear gearbox elements generates vibrations caused by spinning motion of transmission. This affects the pressure and productivity of centrifugal pump. The ...momentum of centrifugal pump in turn affects dynamic characteristics of transmission. In order to find the effect of transmission elements on centrifugal pump we investigate transmission composed of asynchronous electrical engine, gear box, cardan joint and Ziegler Ultra centrifugal pump. We create mathematical models of transmission and centrifugal pumps and investigate how the dynamic effects of transmission influence productivity centrifugal pump. This model can be applied to study the transmission parameters, effect of intake and outflow parameters on productivity of centrifugal pump and presence of cavitation. The paper includes results and conclusions of mathematical model. Santrauka Transmisija su kardanine jungtimi ir netiesiškumais pavarų dėžės elementuose generuoja transmisijos sukamojo judesio virpesius, kurie daro poveikį išcentrinio siurblio siurbliaračio sūkiams, generuojamam slėgiui ir jo našumui. Be to, siurbliaračio apkrovimo momentas veikia transmisijos dinamines charakteristikas. Norint nustatyti transmisijos elementų poveikį išcentrinio siurblio charakteristikoms, nagrinėjama transmisija, kuri sudaryta iš asinchroninio elektros variklio, pavarų dėžės, kardaninės jungties ir firmos „Ziegler Ultra Power“ išcentrinio siurblio. Sukurti transmisijos ir išcentrinio siurblio matematiniai modeliai, ištirta transmisijos dinaminio poveikio įtaka išcentrinio siurblio generuojamam našumui. Šiuo modeliu galima tirti transmisijos elementų parametrų, įsiurbimo ir išėjimo magistralių parametrų poveikį išcentrinio siurblio darbui, ir atvirkščiai, kavitacijos reiškinio atsiradimą išcentriniame siurblyje. Pateikti nagrinėjamos sistemos skaitinio modeliavimo rezultatai ir išvados. Reikšminiai žodžiai: asinchroninis elektros variklis; pavarų dėžė; kardaninė jungtis; išcentrinis siurblys.
Relevance. The considerable part of the mechanized oil production is carried out with electric centrifugal pumps. The submersible induction electromotor is the main part of the pumps. It has low ...resistance to short interruptions of power supply. The setting of the undervoltage protection is applied to decrease influence of the interruptions. The actuating characteristics have the given form and do not consider operating conditions of the submersible electromotor. The change in operating conditions of the submersible electromotor results in a shift of dynamic stability curve and the area between this curve and the actuating characteristic of the undervoltage protection occurs that leads to unreasonable shutdowns of electric centrifugal pumps. It is necessary to develop the adaptive undervoltage protection of the submersible induction electromotor for decreasing a number of such shutdowns. The main aim of the research is to increase submersible induction electromotor stability by development of the adaptive undervoltage protection Objects of the research are undervoltage protection and submersible induction electromotor. Methods: mathematical simulation on the basis of Park-Gorev equations for submersible induction electromotor; imitating modeling of the adaptive undervoltage protection including artificial neural network in a software package Matlab Simulink. Results. The authors have developed a simulation model of the submersible electromotor adaptive undervoltage protection on the basis of an artificial neural network; the undervoltage protection with the adaptive actuating characteristic for the submersible induction electromotor was simulated. The approximation of the actuating characteristic of undervoltage protection to dynamic stability curve will allow increasing a stability reserve on voltage to 12 %.
It is of significance to analyze the performance of eccentric electromotor for the research on the electric vehicle wheel drive system’s operational reliabilities. We developed a fast equivalent ...algorithm in which the two-dimensional finite element calculation results are translated into three-dimensional calculation results. An electromotor with skewed slot was decomposed into straight-slot electromotor units that were series-wound. A prototype electromotor driven by square wave current under healthy and eccentric conditions was calculated, and the computation accuracy of the equivalent algorithm was analyzed. The air-gap magnetic field and induced electromotive force were calculated and contrasted. The study results indicate that the magnetic field distribution and the induced electromotive forces of winding elements with different axis positions were affected transparently by grievous eccentricity, yet the induced electromotive force of one phase winding and average value of torque remained virtually invariable. The reference to reliability analysis of electric vehicle wheel drive system is provided.
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