Mechanical Oscillator Research Articles

Textile-based triboelectric nanogenerator with alternating positive and negative freestanding woven structure for harvesting sliding energy in all directions

A novel textile-based triboelectric nanogenerator (TENG) with woven structure operating in freestanding triboelectric-layer mode, defined as a woven-TENG, has been developed. Whereas most woven-structured TENGs operate in contact-separation mode and consist of one type of triboelectric material, this woven-TENG comprises woven electrodes and woven strips of positive and negative triboelectric material, which form a checker-like pattern over the electrodes with matching periodicity. The implementation of the positive and negative triboelectric material significantly improves the performance of the woven-TENG. Furthermore, in contrast to the conventional grating-structured and woven-structured TENG, which are designed to operate only in one moving direction, this new design also allows the woven-TENG to harvest energy from all-planar directions of movement. The woven-TENG with woven strips of nylon and polytetrafluoroethylenevinyl (PTFE) fabric can generate a root mean square (RMS) open-circuit voltage of 62.9 V, an RMS short-circuit current of 1.77 µA and a maximum RMS power of 34.8 µW at a load resistance of 50 MΩ, a mechanical oscillation of 2 Hz and a contact force of 5 N. This corresponds to a maximum RMS power density of 5.43 mW/m2.

Effect of Joule heating on the performance of micromechanical piezoresistive oscillator

Joule heating is more widely existed in micromechanical resonators, and is also an innovative approach for the implementation of mechanical resonator in a broad range of fields such as timing applications, filters and sensors. However, the physical mechanism by which Joule heating affects the performance of resonator has not been thoroughly studied, and the ability to accurately control heat and suppress thermal noise in micro-and nanomechanical resonators remains a key challenge limiting practical applications as well. In this paper, we established the theoretical model based on temperature variation to explain the physical mechanism of the Joule heating effect on the performance of resonator. In the experiment, when the drain current increased from 3.35 mA to 11.62 mA, the dynamic range enhanced by 20.3 dB, which verified that the drain current can be conducive to enhance the signal-to-noise ratio (SNR) of resonator. Intuitively, adding Joule heating will make more thermal noise for the system, which will deteriorate the frequency stability of oscillator. However, there was a counterintuitive phenomenon in piezoresistive oscillator. Contrary to the capacitive oscillator, for a self-sustained mechanical oscillator based on piezoresistive detection method, the frequency stability of oscillator will be improved as the drain current increases. The experimental result showed that the Allan deviation have improved with a slope of −11.22ppb/mA. Our finding revealed the potential of joule heating for applications in high dynamic range sensors and time reference oscillators, as well as the fundamental study of the temperature variation and energy dissipation in micro and nano systems.

Broadband quantum back action evading measurements of a resonant force

Quantum back action imposes fundamental sensitivity limits to the majority of quantum measurements. The effect results from the unavoidable contamination of the measured parameter with the quantum noise of a meter. Back action evading measurements take advantage of the quantum correlations introduced by the system under study to the meter and allow overcoming the fundamental limitations. The measurements are frequently restricted in their bandwidth due to a finite response time of the system components. Here we show that probing a mechanical oscillator with a dichromatic field with frequencies separated by the oscillator frequency enables independent detection in two outputs and complete subtraction of the measurement noise associated with the quantum back action.

Dynamical bipartite and tripartite entanglement of mechanical oscillators in an optomechanical array

We theoretically propose a method to generate tripartite entanglement of three mechanical oscillators in an optomechanical array. We consider a system comprised of three bichromatically driven optomechanical systems which are coupled to each other via Coulomb interaction of the mechanical oscillators. We show that, for small Coulomb coupling strength, steady tripartite entanglement of the three mechanical oscillators with time periodicity can be generated due to the combined effect of the two-tone drivings and the Coulomb coupling. At large Coulomb coupling strength, the tripartite entanglement exhibits steady entanglement sudden death and revival. The duration of entanglement death during one period can be controlled by the Coulomb coupling strength. The tripartite entanglement is robust against the mechanical thermal noise. Our paper provides us a route for exploring and exploiting controllable and robust multipartite entanglement among macroscopic mechanical oscillators.

Phonon-number resolution of voltage-biased mechanical oscillators with weakly anharmonic superconducting circuits

Observing quantum phenomena in macroscopic objects, and the potential discovery of a fundamental limit in the applicability of quantum mechanics, has been a central topic of modern experimental physics. Highly coherent and heavy micro-mechanical oscillators controlled by superconducting circuits are a promising system for this task. Here, we focus in particular on the electrostatic coupling of motion to a weakly anharmonic circuit, namely the transmon qubit. In the case of a megahertz mechanical oscillator coupled to a gigahertz transmon, we explain the difficulties in bridging the large electro-mechanical frequency gap. To remedy this issue, we explore the requirements to reach phonon-number resolution in the resonant coupling of a megahertz transmon and a mechanical oscillator.

Vector optomechanical entanglement

Abstract The polarizations of optical fields, besides field intensities, provide more degrees of freedom to manipulate coherent light–matter interactions. Here, we propose how to achieve a coherent switch of optomechanical entanglement in a polarized-light-driven cavity system. We show that by tuning the polarizations of the driving field, the effective optomechanical coupling can be well controlled and, as a result, quantum entanglement between the mechanical oscillator and the optical transverse electric mode can be coherently and reversibly switched to that between the same phonon mode and the optical transverse magnetic mode. This ability to switch optomechanical entanglement with such a vectorial device can be important for building a quantum network being capable of efficient quantum information interchanges between processing nodes and flying photons.

Movement-Related EEG Oscillations of Contralesional Hemisphere Discloses Compensation Mechanisms of Severely Affected Motor Chronic Stroke Patients.

Conventional rehabilitation strategies for stroke survivors become difficult when voluntary movements are severely disturbed. Combining passive limb mobilization, robotic devices and EEG-based brain-computer interfaces (BCI) systems might improve treatment and clinical follow-up of these patients, but detailed knowledge of neurophysiological mechanisms involved in functional recovery, which might help for tailoring stroke treatment strategies, is lacking. Movement-related EEG changes (EEG event-related desynchronization (ERD) in [Formula: see text] and [Formula: see text] bands, an indicator of motor cortex activation traditionally used for BCI systems), were evaluated in a group of 23 paralyzed chronic stroke patients in two unilateral motor tasks alternating paretic and healthy hands ((i) passive movement, using a hand exoskeleton, and (ii) voluntary movement), and compared to nine healthy subjects. In tasks using unaffected hand, we observed an increase of contralesional hemisphere activation for stroke patients group. Unexpectedly, when using paralyzed hand, motor cortex activation was reduced or absent in severely affected group of patients, while patients with moderate motor deficit showed an activation greater than control group. Cortical activation was reduced or absent in damaged hemisphere of all the patients in both tasks. Significant differences related to severity of motor deficit were found in the time course of [Formula: see text]-[Formula: see text] bands power ratio in EEG of contralesional hemisphere while moving affected hand. These findings suggest the presence of different compensation mechanisms in contralesional hemisphere of stroke patients related to the grade of motor disability, that might turn quantitative EEG during a movement task, obtained from a BCI system controlling a robotic device included in a rehabilitation task, into a valuable tool for monitoring clinical progression, evaluating recovery, and tailoring treatment of stroke patients.

Punctual mechanical oscillation in modulation of muscular tonus in children with spasticity

Spasticity is a motor condition present in 75 to 88% of children with Cerebral Palsy (CP). One form of treatment is called punctual mechanical oscillation (PO). The current study aimed to study different protocols for the application of PO and the magnitude of their effects. In total, 7children with medical diagnosis of CP and ICD (International Classification of Diseases) were included. The first intervention protocol (Int1) consisted of the application of PO to the spastic muscle tendon and the second intervention protocol (Int2) to the muscle belly ofthe spastic antagonist muscle. For evaluation, the Modified Ashworth Scale (MAS) was used, while simultaneously capturing the mechanomyography (MMG) signals. Data were collected pre-intervention and 1 (Post1), 15 (Post15), 30 (Post30), 45 (Post45), and60 (Post60) minutes after the interventions. The MAS values (median ± interquartile range) post intervention were statistically lower when compared to the pre values in the 2 protocols studied; in Int1between Pre (2 ± 0) andPost15 (0 ± 1.75), Post30 (0 ± 1), Post45 (1 ± 1),and Post60 (1 ± 1), and in Int2only between Pre (2 ± 1) and Post1 (0 ± 1).The values found in the MMG in both its temporal and spectral domains did not follow a pattern (p>0.05). The comparison between the protocols did not demonstrate statistical differences in any characteristics (MAS, MMGMF, and MMGRMS). However, PO was shown to be a therapeutic resource that modulated spasticity for up to 60 minutes after its application, and PO could contribute as a tool to aid the treatment of spasticity.

Quantum coherence in a coupled optomechanical system with atomic ensemble

In this study, we investigate the quantum coherence in a hybrid system comprising an atomic ensemble trapped in a cavity that is coupled with a standard cavity optomechanical system. By the concept of quantum coherence measure for Gaussian states, we show that the quantum coherence initially in a cavity and atom can be transferred to another cavity and the mechanical oscillator. The effects of other parameters related to the hybrid optomechanical system, such as the optical coupling, the detunings of the cavity and atom, and the atom–cavity coupling on the quantum coherence of each subsystem are investigated in detail. In addition, the corresponding bipartite coherence between the mechanical oscillator and other subsystems as well as the total coherence of the system are also analyzed.

Mixed electrolyte effect on the stability of the interface between two immiscible electrolyte solutions

Polarization and interfacial tension measurements at an electrolyte dropping electrode or a sessile electrolyte drop are used to investigate the instability of the interface between the aqueous solution of LiCl and the organic solvent containing a mixture of the electrolytes composed of the non-adsorbing ions, here tetrabutylammonium tetraphenylborate (TBATPB) and bis(triphenylphosphoranylidene) ammonium tetrakis (pentafluorophenyl)borate (BATB). The instability is manifested by a substantial current enhancement and decrease of the interfacial tension accompanied by the vigorous mechanical oscillations of the drop. In contrast, no instability is observed when the organic solvent phase contains TBATPB or BATB alone. It is proposed that the hydrodynamic instability has the origin in the small faradaic current associated with the trace ion transfer, and that the initiating impulse is generated by the perturbation of the stratified distribution of the ions with the significantly different sizes (e.g., TBA+ and BA+) on the organic side of the interface. Effects of the potential and the electrolyte concentration on the current enhancement and the interfacial tension reduction are explained by the kinematic theory that has been established by Aogaki et al. (Electrochim. Acta 23 (1978) 867).

Dynamics and Control of a Magnetic Transducer Array Using Multi-Physics Models and Artificial Neural Networks.

A linear mechanical oscillator is non-linearly coupled with an electromagnet and its driving circuit through a magnetic field. The resulting non-linear dynamics are investigated using magnetic circuit approximations without major loss of accuracy and in the interest of brevity. Different computational approaches to simulate the setup in terms of dynamical system response and design parameters optimization are pursued. A current source operating in baseband without modulation directly feeds the electromagnet, which consists commonly of a solenoid and a horseshoe-shaped core. The electromagnet is then magnetically coupled to a mass made of soft magnetic material and attached to a spring with damping. The non-linear system is described by a linearized steady-space representation while is examined for controllability and observability. A controller using a pole placement approach is built to stabilize the element. Drawing upon the fact that coupling works both ways, enabling estimation of the mass position and velocity (state variables) by processing the induced voltage across the electromagnet, a state observer is constructed. Accurate and fast tracking of the state variables, along with the possibility of driving more than one module from the same source using modulation, proves the applicability of the electro-magneto-mechanical transducer for sensor applications. Next, a three-layer feed-forward artificial neural network (ANN) system equivalent was trained using the non-linear plant-linear controller-linear observer configuration. Simulations to investigate the robustness of the system with respect to different equilibrium points and input currents were carried out. The ANN proved robust with respect to position accuracy.

DEVELOPMENT OF OİL PRODUCTİON IMPROVEMENT TECHNOLOGY

It is important to conduct research without storing wells. Prior to this study, the wells will be shut down to explore the wells and additional work will be done for the survey. The research work itself took 15-20 days, using this research to determine the necessary parameters for the joint operation of the reservoir in a short time. In solving engineering problems, the force often applied to the system is to determine its reaction. In such cases, the correct answer to the question can be obtained on the basis of theoretical calculations. However, this is not always possible, and in some cases, instead of a mathematical model of the object under study, research is conducted to find a similar one. An electrical circuit can be thought of as a similar model of the mechanical oscillations of a solid. Therefore, by studying the motion of an electric charge in an electric circuit, it is possible to apply the oscillations of a mechanical system and the distribution of pressure in a porous medium by studying the distribution of heat in an object. If the final results of the two events are similar, then the modeling can be performed. The formation is considered as a working machine to determine the similarity of the drainage zone of the oil and gas well. In this case, the fluid system is lifted by lifting pipes to a certain height with formation pressure and the production of the well is ensured. As a result of the research, it was found that the mode of operation of the drainage zones of the strata in the wells is close to the mode of operation of centrifugal electric pumps. Keywords: debit, formation pressure, gas flow rate, drainage zone of the well, hydraulic characteristics of discharge line, bottomhole pressure, stress on discharge line of the pump.

An untethered mechanically-intelligent inchworm robot powered by a shape memory alloy oscillator

Shape Memory Alloy (SMA) based actuators have become ideal candidates for use in compact and lightweight applications. These smart materials have often been referred to as artificial muscles due to their high work volume density. In this paper, a flexure-based SMA powered mechanical oscillator is developed to create an inchworm robot. Here, a novel magnetic latch system is used to create a mechanically-intelligent system that allows the abstraction of any sensors such as temperature probes. This insect robot, weighing only 9.7 g, operates without any control logic or micro-controller and is able to perform a crawling gait untethered. An analytical model of the thermal properties of the SMA coil, for the sizing of the robot speed, and an analytical model of the step length of the insect robot is presented and validated. A working prototype, with a speed of 1.55 mms−1, is showcased in this work.

Dynamic Range Enhancement Via Linearized Output in Nanoelectromechanical Systems by Combining High-Order Harmonics

There is a strong non-linearity between the field-emission current amplitude and field intensity. This nonlinearity degrades the dynamic range of digital signal processing in a mechanical oscillator composed of a cantilever. To solve this issue, we propose a linearization method by combining the harmonics of the field-emission current. The proposed method significantly increases the dynamic range. The nonlinearity error is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8.94\times 10^{-3}$ </tex-math></inline-formula> %FS for the proposed method, whereas it is 14.1%FS for the conventional method given by the 2nd harmonic current detection. In addition, the proposed method enables to rake up energy of the higher-order harmonics by utilizing our design framework for combining weights, thereby providing a constant derivative of the output current of the input electric field.

Research of Kinematic Stepping Mechanism

Abstract In this paper, a kinematic analysis of Theo Jansen’s stepping mechanism has been carried out and an algorithm for finding the output link trajectory from the given dimensions of the stepping mechanism elements, implemented by Mathcad program, has been developed. It is possible to output characterising parameters of all intermediate links with any number of intermediate links of a step cycle of the mechanism. The dimensions of the mechanism elements have been selected so that they provide the optimal smooth trajectory of the stepping point, minimising the mechanism oscillations in the vertical plane. A comparison of the trajectories of the foot in this study with the classical trajectory of Theo Jansen and the trajectory from article [7] has been provided. A minimum swing of the oscillation of the centre of mechanism masses in the vertical plane has been selected as an optimality criterion, combined with the maximum smoothness of the trajectory, provided that maximization of the step height is not required.

Abnormal interactions between high-speed edge dislocation and microvoid in BCC metals

The interaction between a high speed edge dislocation and a microvoid has been investigated by molecular dynamics (MD) simulations in BCC crystals of Ta, Fe, V and W in the present work. The focus is placed on the dynamic effect on the dislocation-microvoid interaction. Three interaction scenarios different from static cases, i.e., repeated dislocation oscillations around microvoids, dislocation depinning from microvoid like releasing an elastic slingshot, and formation of abnormal “pull forward” dislocation configuration, have been found for the first time. The “repeated oscillations” can be attributed to the dislocation line tension and dynamic effect, which is analogous to under-damped mechanical oscillator system. For the “releasing slingshot” case, the dislocation first bows out after breaking away from the microvoid, and then a stable “drag backward” dislocation configuration is formed. When further increasing the applied shear stress, the dislocation can accelerate to subsonic speed of roughly0.7CT, with CT being the transverse sound speed, leading to a stable “pull forward” configuration. These different dislocation configurations are closely related to the formation of superjog driven by the dislocation-microvoid interaction. By careful analysis, it is found that the variation of relative mobility between the original edge dislocation on the (110) plane and the superjog segments on the (112) plane with shear stresses perfectly coincides with the above three dislocation configurations. In fact, when the applied shear stress is high enough and the dislocation speed is subsonic, the friction stress on the superjog segments turns to be smaller than that of the original edge dislocation, resulting in the formation of abnormal “pull forward” configuration.

Experiments test Penrose’s hypothesis on massive quantum superpositions

Which types of mechanical oscillators fulfill the criteria to experimentally study the interplay between quantum mechanics and general relativity.

Photothermally induced transparency in coupled-cavity system

We aim to study the properties of the output probe field (OPF) in a system composed of two coupled-optical cavities. A strong pump and a weak probe field drives the left cavity whereas the right-side cavity is coupled to mechanical oscillation via photothermal effect. The two cavities are coupled with optical coupling strength J. Single photothermally induced transparency (PTIT) in a single cavity is realized via thermal effect (2020, Sci. Adv. 6, eaax8256). Following the idea, we report double PTIT in coupled-cavities system. The control of single to double PTIT is realized in the proposed system by properly adjusting the coupling strength J. We further show the enhancement of slow light by adjusting the coupling strength (J) between the cavities. Our proposed scheme facilitates experiments to investigate photothermal effects in an array of optomechanical systems.

Room-Temperature Mechanical Resonator with a Single Added or Subtracted Phonon.

A room-temperature mechanical oscillator undergoes thermal Brownian motion with an amplitude much larger than the amplitude associated with a single phonon of excitation. This motion can be read out and manipulated using laser light using a cavity-optomechanical approach. By performing a strong quantum measurement (i.e., counting single photons in the sidebands imparted on a laser), we herald the addition and subtraction of single phonons on the 300K thermal motional state of a 4GHz mechanical oscillator. Tounderstand the resulting mechanical state, we implement a tomography scheme and observe highly non-Gaussian phase-space distributions. Using a maximum likelihood method, we infer the density matrix of the oscillator, and we confirm the counterintuitive doubling of the mean phonon number resulting from phonon addition and subtraction.

Magnetic torque enhanced by tunable dipolar interactions

We use tunable dipolar-interactions between the spins of nitrogen-vacancy (NV) centers in diamond to rotate a diamond crystal. Specifically, we employ cross-relaxation between the electronic spin of pairs of NV centers in a trapped diamond to enhance the anisotropic NV paramagnetism and thus to increase the associated spin torque. Our observations open a path towards the use of mechanical oscillators to detect paramagnetic defects that lack optical transitions, to investigation of angular momentum conservation in spin relaxation processes and to novel means of cooling the motion of mechanical oscillators.