Swing Mode Research Articles

Tunable Tail Swing of Nanomillipedes.

The physical properties of graphene nanoribbons (GNRs) are closely related to their morphology; meanwhile GNRs can easily slide on surfaces (e.g., superlubricity), which may largely affect the configuration and hence the properties. However, the morphological evolution of GNRs during sliding remain elusive. We explore the intriguing tail swing behavior of GNRs under various sliding configurations on Au substrate. Two distinct modes of tail swing emerge, characterized by regular and irregular swings, depending on the GNR width and initial position relative to the substrate. The mechanism can be explained by the moiré effect, presenting both symmetric and asymmetric patterns, resembling a mesmerizing nanomillipede. We reveal a compelling correlation between the tail swing mode and the edge wrinkle patterns of GNRs induced by the moiré effect. These findings provide fundamental understanding of how edge effects influence the tribomorphological responses of GNRs, offering valuable insights for precise manipulation and operation of GNRs.

Influence of Beam Swing Mode on Cracks of Double-sided Laser Welding of 2195 Aluminum-lithium Alloy T-joint

Influence of Beam Swing Mode on Cracks of Double-sided Laser Welding of 2195 Aluminum-lithium Alloy T-joint

Rapid and easily identifiable blood typing on microfluidic cotton thread-based analytical devices.

In this study, we present a novel swing-elution-based method to achieve rapid, cost-effective, and easily identifiable blood typing assays. Specifically, the method aims to swing the microfluidic cotton thread-based analytical devices (μCTADs) in PBS solution to effectively elute free red blood cells (RBCs) and allow large agglutinated RBCs to remain to precisely determine the blood type. In order to ensure an easily identifiable blood typing assay, fast swing mode needs to be used, and the elution time is evaluated to be >50 seconds. The created μCTADs have been used to successfully classify ABO and RhD blood types in 56 blood samples. Finally, in order to enhance the convenience and portability of blood typing, a blood-typing chip that utilizes a PBS liquid bridge to effectively elute the free RBCs is designed and fabricated based on the above swing-elution principle. Compared with the traditional wicking-elution methods that rely on the wicking effect to weakly elute the RBCs, our method possesses a stronger elution effect to remove the free RBCs inside the inter-fiber gaps or adhered to the fiber surface, resulting in effectively enhancing the identifiability of the elution results and minimizing user interpretation error. Given the simplicity of the blood typing method, we believe that our blood typing method has great potential to be widely applied in resource-limited and developing regions.

Coupling vibration characteristics of the shaft-disk-drum rotor system with bolted joints

In this paper, a finite element (FE) model for rotating-flexible shaft-disk-drum (SDR) system with bolted joints is established based on beam-shell-spring hybrid elements by in-house codes. Rotation-induced effects, that is, centrifugal effect, initial tension, gyroscopic moments, and geometric non-linearity due to large deformation are taken into account. Besides, fixed interface mode synthesis method is applied to improve solving efficiency. The proposed model is verified by the results from literature and experiments. Finally, the effects of the number of bolts, rotating speed, connecting stiffness, and the location of disk-drum on the natural characteristics of SDR system are investigated. The main conclusions are summarized as follows: (1) Modes dominated by different components have different sensitivities to the variations of the number of bolts. (2) The analysis of Campbell diagram indicates that frequency veering phenomenon can be found among the shaft bending (SB) mode, disk transverse (DT) mode, disk swing (DS) mode and drum one-circumferential wave (1CW) mode in low-order modes, and the disk nodal diameter (ND) mode always couples with the drum CW mode in high-order modes. (3) The change of axial connecting stiffness will cause the coupling vibration between the disk and drum, while the change of transverse shear stiffness not only causes the coupling vibration between the disk and the drum, but also the coupling vibration among the shaft, disk and drum. (4) The change of disk-drum location can affect the modes associated with the shaft SB and cause frequency veering phenomena. The disk ND modes and the drum CW modes are not coupled with the shaft SB modes when the number of ND and CW are greater than 2.

Design, Fabrication, and Characterization of a Micro Coriolis Mass Flow Sensor Driven by PZT Thin Film Actuators

A micro Coriolis flow sensor accurately measures small mass flows without being affected by properties of the fluid. This paper presents a micro Coriolis mass flow sensor driven by PZT thin film piezoelectric actuators, which allows a combination of large actuation force, low power dissipation and virtually no self-heating. The sensor was fabricated using surface channel technology, resulting in a tube diameter of 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> and a thin silicon-rich silicon nitride tube wall of 1.2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> thick, with a few additional steps to form the integrated piezoelectric actuators. The integrated actuators can actuate the sensor into both swing mode and twist mode. Both actuation modes were evaluated for different fluids and the results are presented in this paper. In the case of swing mode actuation, an optical readout was used to detect the resulting Coriolis movement, resulting in a relatively low sensitivity. In the case of twist mode actuation, a capacitive readout was used and, in comparison to previously published devices, a high mass flow sensitivity was achieved thanks to an optimized readout design. The measurement results show the read-out noise has a standard deviation of 0.15% of the full scale of 1.8 gh <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> when actuated in the twist mode. [2020-0392]

Local degradation in proton exchange membrane fuel cells with dead-ended anode

The dead-ended anode (DEA) configuration can simplify proton exchange membrane fuel cell (PEMFC) systems and reduce system cost. However, the DEA configuration can also accelerate fuel cell degradation during long-term operations. Understanding the degradation mechanisms is crucial to improve fuel cell durability. In this study, experiments are performed to investigate the local degradation phenomena in PEMFCs during DEA operations. The detailed degradation mechanisms are revealed through various electrochemical analysis. The local polarization curves show that the local fuel cell performance decreases are very non-uniform and the inlet area suffers the most severe performance decrease. Electrochemical measurements indicate that the most serious carbon corrosion in catalyst layer occurs near the anode outlet. However, the most severe local membrane degradation is observed near the anode inlet. Furthermore, we observe that the pressure swing anode supply mode can significantly mitigate fuel cell degradation during DEA operation. The water and gas distributions in the anode are much more uniform with the periodical oscillatory flow under pressure swing mode, reducing local membrane dehydration and avoiding local hydrogen starvation. Thus, both the local membrane degradation and local carbon corrosion are significantly mitigated under the pressure swing mode.

Dynamic characteristics and influencing factors of azimuth axis of a new antenna pedestal

Based on the finite element method, the dynamic characteristics of the azimuth axis of an antenna pedestal were studied. With the help of modal analysis module of finite element software, the modal natural frequency and modal shape of the structure were obtained, and the influence of structural size parameters on its dynamic characteristics was also investigated. Through the research, it can be concluded that the first six natural frequency values of the azimuth axis are 220.21, 220.24, 1178.2, 1519.9, 1531.3, 1531.3 Hz. And the first six modes are shown as follows: the first and second order is the swing mode of the axis, the third order is the up and down stretching mode of the azimuth axis, the fourth order is the torsional vibration mode of the azimuth axis, and the fifth and sixth order are the first bending vibration mode of the azimuth axis. The first and second order natural frequencies of the axis decrease with the increase of size parameters d2 , l1 and l2 , and increase with the increase of size parameters d1 , d3 and d4 . The analysis results provide a theoretical basis for the optimization of the dynamic performance of the azimuth axis.

An approach of controlling the inverter-based generator for use in an islanded microgrid

The controls of power generation by the inverter-based generator are proposed in this work. The proposed control adjusts the active power output by varying the phase angle instead of the conventional frequency variation. The benefit of operating the network by a fixed frequency is that it eradicates the problems associated with the frequency deviation. The PID controls with recommended gain adjustment are proposed to control the power generation. The power generation schemes are adapted from the classical power generation by the synchronous generator, where the modes of operation are Swing, PV and PQ mode. The proposed three modes of operation are adequate to operate fully in a small-scale power system such as in an islanded microgrid. A case study of operating the proposed controls in a microgrid by simulation is used to demonstrate the feasibility of implementation of the controls.

Heading Estimation for Multimode Pedestrian Dead Reckoning

The flexible carrying mode of smartphone brings challenge for Pedestrian Dead Reckoning (PDR) especially for heading estimation with build-in sensors. This paper focuses on POCKET mode and SWING mode and analyzes the correlation between smartphone's rotational motion and pedestrian's walking cycle states and walking direction. Based on the analysis, we propose to use the rotation vector sensor data of smartphone within one walking step to estimate the pedestrian's heading. For POCKET mode, heading is estimated by an improved rotational approach (IRA). A jitter detection algorithm is proposed to extract leg flexion interval. Stable walking direction without 180° ambiguity is obtained from the averaged rotation axis. For SWING mode, a single-point (SP) method is proposed. Heading is estimated from the direction of smartphone's y-axis when it is closest to the horizontal plane. The algorithms are validated with data collected by HUAWEI mate 10 smartphone. The RMS errors are less than 4.37° and 3.38° for POCKET and SWING mode respectively. Superior to previous heading estimation algorithms, our method can converge within one single walking step for both carrying modes without 180° ambiguity.

Fixed bed adsorption as affected by thermodynamics and kinetics: Yellow tuff for CO2 capture

In this work, a yellow tuff has been proposed for the first time as sorbent for CO2 capture. Dynamic breakthrough experiments have been performed in a fixed bed reactor at different temperatures (25–150 °C) and CO2 partial pressures (0.01–0.20 atm), focusing on the process thermodynamics and kinetics. The thermodynamic and kinetic studies highlighted that the CO2 adsorption on the tuff in the low pressure region typical of combustion flue gases can be properly described by Freundlich's isotherm model and by the pseudo-first order kinetic model, respectively, thus indicating a physical, multilayer and heterogeneous surface binding mechanism. Based on the results obtained, it has been demonstrated that, in the framework of a real application for post-combustion CO2 capture, the natural tuff, i.e. a low-cost natural sorbent, could be more conveniently employed in vacuum swing or mixed mode in order to minimize the energy penalty of the process.

Problems of using active-recuperative suspension and ways to solve them

The aim of the work is to reveal the unobvious disadvantages of active-recuperative suspension, as well as to identify possible options for dealing with them. Such problems are the danger of suspension breakdown in the active mode, the impossibility of operating in the regenerative mode when the suspension deformation rate is below the threshold, and the system operation in swing mode. The novelty of the work lies in the fact that these aspects of the functioning of the active-recuperative suspension system were not previously considered. The problem of the increased risk of suspension breakdown is that in the active mode, the deformation of the elastic device occurs not only due to the work of external disturbance (road irregularities), but also due to the work performed by the actuator. The following solutions are offered: correct selection of system parameters; collection of additional information about the roughness profile; introduction of preventive measures into the control algorithm. The problem of the impossibility of operating in a regenerative mode at a suspension deformation rate below the threshold is that the electromotive force of induction on the rotor winding at low speeds may be lower than the threshold charging voltage at the terminals of the energy storage device. The following solutions are offered: dry friction in the suspension; introduction of a shock absorber with a pronounced degressive characteristic into the suspension structure; lowering the charging threshold voltage by separating the supply and charging circuits using a voltage converter; introduction of a “scattering chain” into the armature chain; optimal control of the excitation circuit. The problem of the system operation in the swing mode is that, under certain conditions, energy is supplied to the oscillatory system through the actuator, resulting in a gradual increase in the oscillation amplitude. The following solutions are proposed: the introduction of an additional damper or regenerative connection on the deformation rate of the suspension.

POWER SYSTEM STABILIZER DESIGN USING NOTCH-FILTER – BARKA II (OMAN) - CASE STUDY

The use of power system stabilizers (PSSs) to damp power system swing mode oscillations is of extreme practical importance. This manuscript presents an approach to the stabilization of a single machine infinite bus system (SMIB). The proposed control is based on the notch-filter approach to cancel the poles near to the imaginary axes. The approach is based on the root locus method. Application to Barka II power station connected to the main interconnected system of Oman is presented. The peak load at summer is considered as the system is near to instability. The Barka SMIB is modeled as a fourth order non-linear system. A linearized model is then obtained using MATLAB/Simulink. The simulation results validate the proposed design for the PSS.

Computation of the controllable swing mode spectrum of FACTS and HVDC in large power systems

This paper presents computation of swing modes of a large power system that could be significantly affected by power swing damping controllers in FACTS or HVDC devices at a given location. Modal controllability is a suitable measure to isolate these modes for analysis. Computation of the controllable swing mode spectrum is useful, especially in situations where the controller structure and feedback signals are not frozen (e.g., at the planning stage). This paper proposes two important steps that allow us to map the problem of finding highly controllable swing modes to the problem of finding the swing modes that have high transfer function residues (for which efficient algorithms are available). The steps are: (a) normalization of the eigenvectors corresponding to different modes and (b) identification of specific feedback signals for each type of FACTS/HVDC device such that the modal observability and modal controllability are tightly coupled. Once the mapping is done, a computationally efficient method like the Subspace Accelerated Dominant Pole Algorithm [16] (SADPA) can be adapted to find the highly controllable swing modes. The effectiveness of this approach is demonstrated by case studies of FACTS and HVDC devices in a 16-machine system and the Indian power grid.

Design and Efficiency Research of a New Composite Vibrating Screen

A new composite vibrating mode is presented in this paper. Modeling and dynamic analysis are studied according to two‐degree‐of‐freedom systems theory. The effects of vibration parameters, including swing angle, swing frequency, vibrating direction angle, and translation frequency, on the screening efficiency were researched by means of experiment research over a new laboratory‐scale composite vibrating screen which is designed based on the new composite vibrating mode. The results are analysed in terms of curves and fitting equations. Compared to the translation mode and swing mode, the screening performance of the new composite vibrating mode, both in screening efficiency and in processing capacity, is significantly improved.

Natural characteristic analysis of wind turbine drivetrain considering flexible supporting

The mechanical system of wind turbine is much complicated and can be divided into the drivetrain and supporting portions. The drivetrain consists of wheel, main shaft, gearbox, generator, etc. and the supporting portion mainly consists of a tower and a cabin. In order to reduce the unit cost of electricity, the capacity and size of wind turbine are increased gradually in the past years. Meanwhile, with the increase of the wind turbine height, the tower actually becomes more flexible as the supporting part. And the influence of the supporting tower flexibility becomes stronger due to the varying wind loads both in magnitude and direction. Using the rigid–flexible coupling multibody dynamic theory, the coupled dynamic model of the wind turbine drive train was developed considering the flexible supporting. Then the natural characteristics of the system were computed and investigated. For the dynamic modeling, the blades, the tower and main shaft were modeled as flexible bodies, while the other components, such as the hub and the gearbox, were modeled as rigid bodies. The potential resonance frequencies of the system were discussed through the Campbell diagram and the modal energy distribution analysis. The results show that the natural frequency of swing mode shapes for the tower was 0.399 Hz and 0.405 Hz. The first natural frequency of drivetrain, which represented a torsional vibration mode, was 1.64 Hz. From the Campbell diagram and the modal energy distribution analysis, resonances would not occur within the normal operating speed range for the drivetrain. And a comparison analysis indicated that the flexible supports would increase the bearing loads along axial direction and radial direction, especially in main shaft and torque arm, but that influence was not obvious at parallel stage. However, to some extent, the flexible supports can decrease the loads fluctuation of drivetrain. Finally, the online vibration experiments were carried out in the wind field. The vibration characteristics of the wind turbine drivetrain were analyzed and the experimental results also compared well with the theoretical dynamic results.

Bending modes and transition criteria for a flexible fiber in viscous flows

The present paper follows our previous work in which a coupling approach of smoothed particle hydrodynamics (SPH) and element bending group (EBG) was developed for modeling the interaction of viscous incompressible flows with flexible fibers. It was also shown that a flexible object may experience drag reduction because of its reconfiguration due to fluid force on it. However, the reconfiguration of deformable bodies does not always result in drag reduction as different deformation patterns can result in different drag scales. In the present work, we studied the bending modes of a flexible fiber in viscous flows using the presented SPH and EBG coupling approach. The flexible fiber is immersed in a fluid and is tethered at its center point, while the two ends of the fiber are free to move. We showed that the fiber undergoes four different bending modes: stable U-shape, slight swing, violent flapping, and stable closure modes. We found there is a transition criterion for the flexible fiber from slight swing, suddenly to violent flapping. We defined a bending number to characterize the bending dynamics of the interaction of flexible fiber with viscous fluid and revealed that this bending number is relevant to the non-dimensional fiber length. We also identified the critical bending number from slight swing mode to violent flapping mode.

New development in flow‐through pressure‐swing frequency response method for mass‐transfer study: Ethane in ZIF‐8

A new pressure‐swing frequency response (PSFR) method has been developed to study mass transfer in adsorption systems as a function of temperature and pressure, from −70 to 180°C, and up to 7 bar. New in‐phase and out‐of‐phase functions have been derived for the PSFR in a general way to allow information extracted from it independent of whether the system is operated in a batch volume swing or a flow‐through pressure swing mode. A new mathematical model that considers distribution of diffusion rates has been introduced to account for diffusive transport in heterogeneous samples. Numerical simulation results have shown that a single rate diffusion model works well when heterogeneity can be described by a normal distribution, but not for asymmetrically bimodal distributions. As a test reference system, the transport of ethane in ZIF‐8 was investigated at different pressures and temperatures using the new PSFR method. The mass transfer was found to be dominated by micropore diffusion. Diffusivity was found to be weakly dependent on pressure or loading, but quite strongly dependent on temperature. The results agree very well with our independent batch volume frequency response technique experiments. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1077–1090, 2017

Analytical Concepts for Reactive Power Based Primary Frequency Control in Power Systems

This paper introduces a novel idea for adding virtual inertia in power systems by controlling the frequency swing dynamics through voltage channel. The purpose is to develop a frequency-based supplementary VAR modulation to assist governor action during power imbalance events. In this aim, we propose a two-band power system stabilizer, tuned for very low-frequency common swing mode, to adaptively adjust reference voltage of a Synchronous Condenser (SC) and modulate its reactive power on a second-by-second basis. The feasibility of this idea is supported by theoretical and simulation evidences. From theoretical side, we formulate a computational procedure to measure the degree of control impact, accompanied by sensitivity analyses around varying operating points. On the simulation side, we perform extensive studies on four well-known IEEE multi-machine test systems. The results show that VAR modulation by SC has a considerable impact on the minimum post-contingency frequency (frequency nadir), even more than so-called load modulation methods in some cases, which in fact has not been given enough attention in the past. In addition, we show that the proposed method can aid governors to improve primary frequency response particularly in low inertia power systems by reducing post-event frequency settling time and bias.

Two-mode navigation method for low-cost inertial measurement unit-based indoor pedestrian navigation

The traditional inertial navigation system-based indoor pedestrian navigation method is not suitable to all the conditions, since its data fusion model is designed only for a single condition. In order to achieve better performance, a two-mode navigation method for indoor pedestrian navigation is proposed in this work, which includes the stance mode and the swing mode. When the person’s foot is in a stance phase, the stance mode is used to correct the velocity error and yaw error. When the person’s foot is in a swing phase, the swing mode works and only the yaw error is able to be corrected. For verification, a real indoor test has been done to assess the performance of the proposed two-mode method. The position root-mean-square error (RMSE) value is 1.9265 m during a 176-m traverse, and the RMSE of yaw is 0.20734 rad. These results demonstrate that our method is effective to reduce the error compared with the conventional schemes.

Turbulent kinetic energy estimates from profiling wind LiDAR measurements and their potential for wind energy applications

This study shows that turbulent kinetic energy (TKE) estimates, derived from static LiDARs in Doppler Beam Swing (DBS) mode, permit a qualitative and quantitative characterization and analysis of turbulent structures as wind turbine wakes, and convective or shear generated eddies in the lower atmospheric boundary layer. The analysed data, collected by a WINDCUBE™ v1 in a wind park in Austria, is compared to WINDCUBE™ v1 and sonic data from the WINd Turbine Wake EXperiment Wieringermeer (WINTWEX-W). Although turbulence measurements with a WINDCUBE™ v1 are limited to a specific length scale, processed measurements above this threshold are in a good agreement with sonic anemometer data. In contrast to the commonly used turbulence intensity, the calculation of TKE not only provides an appropriate measure of turbulence intensities but also gives an insight into its origin. The processed data show typical wake characteristics, as flow decelerations, turbulence enhancement and wake rotation. By comparing these turbulence characteristics to other turbulent structures in the atmospheric boundary layer, we found that convection driven eddies in the surface layer have similar turbulence characteristics as turbine wakes, which makes convective weather situations relevant for wind turbine fatigue considerations.