Circular Pump Research Articles

Simplified discrete model for axisymmetric dielectric elastomer membranes with robotic applications

Soft robots utilizing inflatable dielectric membranes can realize intricate functionalities through the application of non-mechanical fields. However, given the current limitations in simulations, including low computational efficiency and difficulty in dealing with complex external interactions, the design and control of such soft robots often require trial and error. Thus, a novel one-dimensional (1D) discrete differential geometry (DDG)-based numerical model is developed for analyzing the highly nonlinear mechanics in axisymmetric inflatable dielectric membranes. The model captures the intricate dynamics of these membranes under both inflationary pressure and electrical stimulation. Comprehensive validations using hyperelastic benchmarks demonstrate the model’s accuracy and reliability. Additionally, the focus on the electro-mechanical coupling elucidates critical insights into the membrane’s behavior under varying internal pressures and electrical loads. The research further translates these findings into innovative soft robotic applications, including a spherical soft actuator, a soft circular fluid pump, and a soft toroidal gripper, where the snap-through of electroelastic membrane plays a crucial role. Our analyses reveal that the functional ranges of soft robots are amplified by the snap-through of an electroelastic membrane upon electrical stimuli. This study underscores the potential of DDG-based simulations to advance the understanding of the nonlinear mechanics of electroelastic membranes and guide the design of electroelastic actuators in soft robotics applications.

Proposal and detailed theoretical analysis on a photonic neural network with optically pumped Spin-VCSEL spiking neurons

A dual-layer photonic spiking neural network (PSNN) was constructed, where multiple optically pumped spin vertical-cavity surface-emitting lasers (Spin-VCSELs) were proposed as spiking neurons. Based on a detailed theoretical analysis of leaky integrate-and-fire (LIF) and refractory period characteristics of Spin-VCSEL neurons, the training and testing performance for the studied PSNN was evaluated using two standard pattern classification tasks (Iris dataset, simple digit recognition). The results showed that, by selecting appropriate parameters such as frequency detuning and number of pre-synaptic neurons, etc., higher training/testing accuracies beyond 90% can be obtained. When compared with traditional electrically pumped VCSEL, a threshold reduction of up to 50% can be achieved under nanosecond scale spin relaxation time and circular polarization optical pumping, the feasibility of realizing high accuracy (88%) pattern classification near the reduced threshold was also verified. Therefore, optically pumped Spin-VCSEL neurons can become a valuable new choice for high-performance PSNN with reduced power consumption.

Stability of vortices in exciton-polariton condensates with spin–orbital-angular-momentum coupling

The existence and dynamics of stable quantized vortices is an important subject of quantum many-body physics. Spin–orbital-angular-momentum coupling (SOAMC), a special type of spin–orbit coupling, has been experimentally achieved to create vortices in atomic Bose–Einstein condensates (BEC). Here, we generalize the concept of SOAMC to a two-component polariton BEC and analyze the emergence and configuration of vortices under a finite-size circular pumping beam. We find that the regular configuration of vortex lattices induced by a finite-size circular pump is significantly distorted by the spatially dependent Raman coupling of SOAMC, even in the presence of a repulsive polariton interaction which can assist the forming of stable vortex configuration. Meanwhile, a pair of vortices induced by SOAMC located at the center of polariton cloud remains stable. When the Raman coupling is sufficiently strong and interaction is weak, the vortices spiraling in from the edge of polariton cloud will disrupt the polariton BEC.

Polarization-dependent intensity ratios in double resonance spectroscopy.

Double Resonance is a powerful spectroscopic method that unambiguously assigns the rigorous quantum numbers of one state of a transition. However, there is often ambiguity as to the branch (ΔJ) of that transition. Spectroscopists have resolved this ambiguity by using the dependence of the double resonance intensity on the relative polarization directions of pump and probe radiation. However, published theoretical predictions for this ratio are based upon a weak (i.e., non-saturating) field approximation. This paper presents theoretical predictions for these intensity ratios for cases where the pump field is strongly saturating in the two limits of transitions dominated by homogeneous or of inhomogeneous broadening. Saturation reduces but does not eliminate the magnitude of the polarization effect (driving the intensity ratio closer to unity) even with strong pump saturation. For the case of an inhomogeneously broadened line, such as when Doppler broadened linewidth dominates over the power-broadened homogeneous line width, a large fraction of the low pump power polarization anisotropy remains. This paper reports predicted polarization ratios for both linear and circular pump and probe field polarizations. The present predictions are compared with experimental measurements on CH4 ground state → ν3 → 3ν3 transitions recently reported by de Oliveira et al.63 and these are in better agreement than with the weak field predictions.

High-efficiency broad-linewidth widely-tunable mid-infrared OPO based on fan-out PPLT

We reported a high-efficiency, broad-linewidth, wide-tuning-range singly-resonated optical parametric oscillator (OPO) based on a fan-out PPLT crystal. When the PPLT crystal was operated at 120 °C and pumped by Q-switched 1064 nm laser at 14.17 W with a circular pump profile, the overall output power of OPO was 7.22 W (η = 50.4%) for both the signal and idler waves. The central wavelength and linewidth of the mid-infrared (MIR) laser were 3770 nm and ∼40 nm. A wavelength tuning range of 3538–3941 nm was accomplished by adjusting the crystal period through simple mechanical movement. Due to the larger coverage of gratings with an elliptical pump profile, the output linewidth of the MIR laser was further broadened to ∼100 nm, which is ten times more than other non-fan-out PPLT OPOs. Both pumping methods with different profiles were operated at 30 kHz, 49.2 ns for the 1064 nm laser, the power fluctuation of the obtained MIR laser was within 3.5%.

HORIZONTAL CIRCULAR PUMPING WELLS TO MINIMIZE SALINE WATER UPCONING: WATER RESOURCE DEVELOPMENT MEASURE FOR TROPICAL SAVANNA CLIMATIC NINH THUAN AREA, VIETNAM

Link for citation: Nguyen Van Hoang, Trinh Hoai Thu, Shakirov R.B., Syrbu N.S., Tran Thi Thuy Huong, Lee N.S. Horizontal circular pumping wells to minimize saline water upconing: water resource development measure for tropical savanna climatic Ninh Thuan area, Vietnam. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 4, рр.209-220. In Rus.
 The relevance. The Southern central region of Vietnam, including Ninh Thuan province, has a tropical savanna climate and has been heavily suffering from drought and water salinization. Ninh Thuan province has faced severe droughts in recent years because of the increase of the frequency and intensity of extreme weather conditions, the water scarcity, and the salinity of the groundwater. The distribution of fresh and saline groundwater in Ninh Thuan plain has three zones: 1) zone of entire profile with fresh groundwater; 2) zone of the upper profile's with fresh groundwater and of the lower profile's with saline groundwater, and 3) zone of entire profile with saline groundwater. The groundwater abstraction facilities in the first zone are vulnerable to salinization from surrounding saline water, while in the second zone are vulnerable to the upconing saline water from below. The aim: to determine the optimal groundwater pumping in respect to given water level drawdown, to show that the horizontal circular wells are the best for minimization of saline water upconing, to determine the relationship between the saline water upconing height and the radii of the horizontal circular wells. Objects: tropical savanna climate, coastal plain, fresh and saline groundwater, aquifer with fresh water in the upper profile and saline water in the lower profile, circular groundwater wells, saline water upconing. Methods: finite element method, dynamic programming, Dagan–Bear model of saline water upconing, superimposition principle in dealing with multiple pumping points for identification of overall saline water upconing. Results. Different schemes of pumping fields with either vertical wells or horizontal circular wells with different radii were analyzed for saline water upconing. The time of saline upconing height in all the alternative schemes were determined. A very well regression curve of the relationship between the time saline water upconing to the horizontal circular wells and the circular well radii was obtained. The analysis results are extremely useful supporting well design in terms of minimization of saline water upconing.

Meet the Association: Europump

Vanni Vignoli, president of Europump, discusses energy efficiency and contributing to a greener, more circular pump industry.

Spontaneous giant vortices and circular supercurrents in a trapped exciton-polariton condensate.

We theoretically study an exciton-polariton condensate trapped in a harmonic potential with an annular pump. With a circular pump, predictions were made for a spontaneous rotating vortex lattice packed by singly quantized vortices. If the circular pump is replaced by an annular pump, singly quantized vortices are absorbed into the central hole and form a multiply quantized vortex. For a sufficiently narrow annular width, all vortices are absorbed into the central hole, ultimately forming a giant vortex with supersonic circular supercurrents flowing around it. Vortex-antivortex pairs can be generated if a defect is present in these supersonic circular supercurrents. We further discover that the motion of the vortex-antivortex pairs depends on the position at which they were generated. We suggest that this property can be used to control whether the velocity of the circular supercurrents is above or below the sound velocity.

High power and efficient operation of a Ho:Y2O3 ceramic laser with over 210 W of output power at 2.1 µm.

We report on power scaling and efficient operation of a Ho:Y2O3 ceramic laser at 2.1 µm in-band pumped with an incoherently beam combined high power and narrow-linewidth Tm fiber source at 1931.2 nm. The 0.5 at.% Ho3+ doped Ho:Y2O3 ceramic is fabricated in-house with scattering loss of < 0.25% cm-1. Up to 210.5 W of continuous-wave output power has been generated at 2117 nm for 366 W absorbed pump power shaped with a one-dimensional top-hat profile, corresponding to a slope efficiency of 60.0% with respect to the absorbed pump power. A slope efficiency of 67.5% has been demonstrated with 160 W of output power using a circular beam pump configuration. Results presented in this work verify the superior power scaling capability of a Ho:Y2O3 ceramic laser with high efficiency at ∼2.1 µm.

Influence of transverse carrier diffusion on two-dimensional optical rogue waves in broad-area semiconductor lasers with a saturable absorber

The statistics and dynamics of two-dimensional rogue waves in a broad-area semiconductor laser with an intracavity saturable absorber are numerically investigated under the effect of transverse carrier diffusion. We show that lateral diffusion of carriers alters the statistics of rogue waves by enhancing their formation in smaller ratios of carrier lifetimes in active and passive materials while suppressing them when the ratio is larger. The temporal dynamics of the emitted rogue waves is also studied and show that the finite nonzero transverse carrier diffusion coefficient gives them a longer duration. To further approach a realistic experimental situation, we also investigate the statistics and dynamics of rogue waves by simulating a circular disk-shape pump which replaces the flat pump profile typically used in numerical simulations of broad-area lasers. We show that a finite pump shape reduces the number of emitted rogue waves per unit area both below and above the laser threshold for every carrier lifetime ratio. The temporal width of the emitted rogue waves is also shown to decrease as a consequence of removing the nonphysical effects of the infinite flat pump on carrier dynamics.

Interpolarization Forward Stimulated Brillouin Scattering in Standard Single‐Mode Fibers

AbstractForward stimulated Brillouin scattering in standard single‐mode fibers draws increasing interest toward sensing and signal processing applications. The process takes place through two classes of guided acoustic modes: purely radial ones and torsional‐radial modes with twofold azimuthal symmetry. The latter case cannot be described in terms of scalar models alone. In this work, the polarization attributes of forward stimulated Brillouin scattering in single‐mode fibers are investigated in analysis and experiment. Torsional‐radial acoustic modes are stimulated by orthogonally polarized pump tones, a first such report in standard single‐mode fibers. The scattering of optical probe waves by torsional‐radial modes may take up the form of phase modulation, cross‐polarization coupling, or a combination of both, depending on polarization. Lastly, this analysis predicts that circular and orthogonal pump tones may stimulate acoustic vortex beams: torsional‐radial modes that are rotating. The rotation represents the transfer of angular momentum between the polarization degree of freedom of the light field and the acoustic wave.

Quantum dot membrane external-cavity surface-emitting laser at 1.5 μm

A membrane external-cavity surface-emitting laser (MECSEL) with an InAs/InP quantum dot (QD) based gain region is demonstrated. The pumping scheme employs a 90° off-axis parabolic mirror to focus the diode laser pump beam to a nearly circular pump spot. With this pump arrangement, the QD MECSEL with SiC heat spreaders produced 320 mW output power at room temperature with direct emission in the near-infrared at 1.5 μm. We report a record value of 86 nm for the tuning range at this wavelength region, owing to a broad QD gain bandwidth and wide tunability in MECSELs.

Analysis of axial force of double circular arc helical gear hydraulic pump and design of its balancing device

In view of the axial force produced in the working process of double arc helical gear hydraulic pump, the theory of differential equation of curve and curved surface was utilized so that the calculation formula of axial force was obtained and the relationship between the axial force and structure parameters of gears was clarified. In order to balance the axial force, the pressure oil in the high pressure area was introduced into the end face of the plunger to press the plunger against the gear shaft, and the hydrostatic bearing whose type is plunger at the end of the shaft was designed. In order to verify the balance effect of axial force, the leakage owing to end clearance and volume efficiency of gear hydraulic pump before and after the balancing process was analyzed. This paper provides a new analysis idea and balance scheme for the axial force produced in the working process of the double arc helical gear hydraulic pump, which can reduce the leakage owing to end clearance caused by the axial force and improve the volume efficiency of the gear hydraulic pump.

Numerical analysis of thermal storage characteristics of stacked lunar regolith spheres

As a kind of in-situ resource utilization, the regolith thermal energy storage is a promising way to solve the energy crisis of manmade moon base during the long lunar nighttime of 350 h. In this paper, a lunar regolith thermal storage system is designed and two different stacking methods of lunar regolith spheres are proposed, the thermal storage characteristics of stacked lunar regolith spheres is investigated numerically. The porous media model is applied to simulate the transient temperature and helium flow fields inside regolith thermal reservoir. The influences of regolith sphere diameter and pump pressure on the performance of a lunar regolith thermal reservoir are analyzed. The results show that there exist optimization regolith sphere diameter and pump pressure to the performance of regolith thermal energy reservoir. The optimization circular pump pressure for helium flow is dependent on the stacking method. When the pump pressure increases over 450 Pa, the face centered cubes (FCC) stacking method shows a maximum advantage of 305.6 kWh heat storage amount over the simple cubes (SC) stacking method. The designed lunar regolith thermal reservoir has the thermal storage density of 0.25 kWh kg−1 for one lunar day.

Temperature rise of journal bearing of the high-speed circular arc gear pump

A “circular arc–involute–circular arc” circular arc gear pump was developed based on a gear meshing principle and coordinate transformation as well as an accurate calculation model of the radial force. The dependence of the radial force on the meshing angle was investigated. The temperature rise of journal bearings in the pump was evaluated for bearings with and without herringbone grooves. Furthermore, the influence of the rotational speed and outlet pressure on this rise was assessed. The results revealed using herringbone groove on the inner wall of bearing was effective in reducing the temperature increase. Therefore, the use of grooves represents a suitable method of reducing the temperature rise in the journal bearings of a high-speed gear pump.

Pump-Controlled Plasmonic Random Lasers from Dye-Doped Nematic Liquid Crystals with TiN Nanoparticles in Non-Oriented Cells

Manipulation of the performance of the random lasers from dye-doped nematic liquid crystals with TiN nanoparticles in non-oriented cells is studied. The experimental results show that the introduction of TiN nanoparticles into dye-doped nematic liquid crystals significantly reduces the threshold of random lasing due to the localized surface plasmon resonance of TiN nanoparticles. The emission spectrum of random lasers can be controlled by the shape of the pump spot. The threshold of random lasers increases with the decrease of the length of pump stripe. In order to obtain the emission spectrum with fine discrete sharp peaks, the narrow pump stripe is more effective than the circular pump spot. When the pump area is more like a circle, the emission spectrum is more like an amplified spontaneous emission. The underlying mechanisms of these phenomena are discussed in detail. This study provides a promising platform for designing the high-quality and low-threshold random lasers which can be controlled by the shape of the pump spot.

ZnO indiffused MgO:PPLN ridge waveguides.

We have demonstrated the first MgO:PPLN ridge waveguides based on ZnO indiffusion and dicing. The fabrication process utilizes ductile regime dicing of a planar waveguide layer producing second harmonic generation (SHG) devices with a near-symmetric sinc2 spectral profile, indicating highly uniform 40 mm long devices. A near circular pump mode is also obtained enabling efficient coupling to single mode telecommunication fibers. A conversion efficiency of 145%/W, for 1560-780 nm SHG, has been measured.

The design and analysis of a high-speed circular arc gear pump journal bearing

A series of problems arise when a gear pump operates at high speed, including instability of the rotor, deformation of the chamber, and wear of the journal bearing. Among all failure modes, journal bearing wear is the most serious. The wear of journal bearings of a circular arc gear pump that operates at high speed is thus presented in this article. A journal bearing that offsets the unbalanced radial force is designed by analysis of the fluid and determination of eccentricity of the gear shaft. Experiments show that the wear of the new journal bearing is effectively reduced.

General model of DPAL output power and beam quality dependence on pump beam parameters: experimental and theoretical studies

A general model that reproduces the output parameters of diode-pumped alkali lasers with different pump beam apertures and shapes is reported. Comprehensive experimental and theoretical parametric studies of static diode-pumped Cs lasers are presented, including the dependence of the output laser power and the beam quality factor M2 on the power of the pump beam for different shapes of the pump beam, pump-to-laser beam overlaps, and laser cell lengths. Two different pump lasers with circular and rectangular beam shapes and pump powers of 65 W and 7 W, respectively, were used in two sets of experiments. An optical model of multi-transverse mode operation of alkali vapor lasers [Opt. Express25, 19767 (2017)OPEXFF1094-408710.1364/OE.25.019767] was modified and applied to the experimental results. The values of the laser power and M2 predicted by the model are in good agreement with the measured values for a wide range of the laser parameters.

Signatures of self-trapping of trions in monolayer MoS2

The peak of the photoluminescence (PL) spectrum associated with the A− trion in monolayer MoS2 on SiO2/Si substrate is typically red shifted in energy relative to its absorption peak by ∼20 meV. Circular polarization anisotropy and pump laser intensity dependence of PL indicates that the A− trion is not localized at a defect. Raman lines in monolayer MoS2 are enhanced and additional lines are seen when the excitation laser has photon energy close to the trion/exciton absorption resonance, indicating their coupling with phonons. Analysis of time resolved PL measurements show that the A− trion emission has a finite rise time of ∼25 ps, unlike the defect bound exciton emission which is also seen. The above characteristics when considered together suggest that trions in monolayer MoS2 could be subject to momentary weak self-trapping through interaction with phonons, a hitherto unexplored property of trions/excitons in two-dimensional transition metal dichalcogenide semiconductors.