Mode Transfer Research Articles

A new design for mode transfer-based harmonic tuned power amplifier (MHPA)

Available onlineThis paper presents the design, implementation and measurement results for a 0.8–2.1 GHz Mode transfer-based Harmonic tuned Power Amplifier (MHPA). The design based on a new combination of the hybrid modes. The proposed design approach uses the mode transfer technique to combine two harmonic tuned power amplifier modes, i.e., classes F3 and F3-1, in order to obtain a broadband hybrid mode PA. First, theoretical limitations of maximum attainable Fractional Bandwidth (FBW) in a single mode harmonic tuned PA (HTPA) are investigated where we have n harmonic impedances and there is no overlapping between harmonics. Then, mode transfer technique is applied to overcome bandwidth restriction of F3 and F3-1 modes of HTPA. As a result, the maximum FBW in a single mode HTPA with 3 harmonic impedances is improved from 40 % to 66 % (equivalent to one octave) when it being used in a hybrid structure. To evaluate the proposed design approach, a broadband PA, which is working at one octave bandwidth (1–2 GHz), is designed and fabricated. Performance of the designed MHPA is acceptable at the 0.8–2.1 GHz frequency band. Experimental results show that the designed MHPA achieves 89.9 % maximum and 76.3 % average drain efficiency in the 0.8–2.1 GHz frequency band.

Evaluation Model for a Port Hinterland Intermodal Freight Network Considering Environmental Impacts and Capacity Constraints

The huge demand for containerized cargo and the low market share of rail and inland waterway transport in the hinterland freight system in China are causing severe traffic congestion and pollution. Therefore, this paper focuses on innovative modeling to evaluate the effects of transport policies on the reduction of carbon emissions and the mode shift from road to low-carbon modes in a three-mode port hinterland freight network. The proposed model can capture the main characteristics of the freight system such as mode transfer at inland terminals, transport capacity and processing capacity constraints, flow-dependent link performance functions, and shippers’ perceptual error of generalized transport costs. The model assumes that shippers choose transport route, mode, and inland terminal at the same time in a user equilibrium manner, and that bundles of container flow passing competing ports follow the logit formulation. Computational results based on the freight network in the Yangtze River Economic Belt in China indicate that carbon tax, intermodal transport subsidy, and capacity expansion policies can reduce total carbon emissions and promote mode shift from road transport to rail and inland waterway transport, and policy packages show better network performance compared with a single policy type. It is noted that transport policies sometimes lead to the paradoxical phenomenon. Finally, sensitivity analyses are carried out on parameters of cost, time, carbon emissions, and error to test the robustness of the model.

Computational analysis of metal transfer mode, dynamics, and heat transfer under different pulsating frequencies in pulsed wire-arc additive manufacturing

Abstract A numerical model of the metal transfer process was developed using the thermomagnetohydrodynamic equations and the phase-field method to investigate the influence of pulse frequency on the metal transfer mode, dynamics, and thermal behavior in the pulsed wire-arc additive manufacturing (WAAM) process. The control of droplet transfer mode, dynamics, and thermal behavior is essential in WAAM; otherwise, several potential defects such as high residual stresses and distortion, poor dimensional accuracy, and surface quality may occur due to uneven heat input condition and process instability. Therefore, in this study, eight sets of pulse frequencies ranging from 50 to 225 Hz, in steps of 25 Hz, using identical power source parameters, such as pulse duty cycle and average current of 25.4% and 152 A, respectively, were considered and compared for a nearly square current waveform. The results reveal that only the current pulses with a medium frequency regime (100–175 Hz) achieve the one-droplet-per-pulse mode of metal transfer. Moreover, an increase in pulse frequency leads to a shorter necking length of the pendent droplet and a significantly lower average speed and temperature of the detached droplet. The results for the heat flux analysis indicate that Joule heating and arc heating decrease due to the increase in pulse frequency, whereas the sheath heating remains almost constant using different pulse frequencies. The proposed numerical scheme provides a detailed understanding of controlling and tailoring the different metal transfer modes and their metal transfer stability during WAAM, which benefits further process optimization and control.

A progressive fault diagnosis method for rolling bearings based on VMD energy entropy and a deep adversarial transfer network

Bearing fault diagnosis with extensive labeled fault data has been achieved. In engineering, most machines are in a healthy state. When a fault does occur, the machine is shut down as soon as possible, thus it is difficult and uneconomical to collect enough fault data with labels to carry out a fault diagnosis. To solve the problem, a hybrid fault diagnosis method for rotating machinery, based on variational mode decomposition energy entropy (VMD-EE) and transfer learning (TL), is proposed. First, we decompose the original signal using VMD, calculate the EE value of the modal components, then build a dataset using fault data from these components. Second, a deep residual neural network is proposed to extract high-dimensional features from the dataset and divide the data into source and target domains according to the working conditions. Finally, W-distances are introduced to dynamically evaluate the importance of the conditional and marginal distribution probabilities to minimize the loss, with a feature-based TL method being used to dynamically balance the distribution adaption and reduce the difference in the probability distributions of the two domains. The proposed method is validated using the datasets of Case Western Reserve University and a machinery fault simulator platform. The VMD-based intelligent health detection and statistical analysis solve the problem of mode mixing very well and accurately detect signal faults, or not, by , the threshold of VMD-EE. Meanwhile, the accuracy of TL-based neural network fault diagnosis is up to 99.4%, and the losses are kept at around 0.02. These results show the accuracy and robustness of the proposed method in the absence of datasets and under varying operating conditions.

Camouflaged object detection via Neighbor Connection and Hierarchical Information Transfer

Camouflaged Object Detection (COD) aims to detect objects with high similarity to the background. Unlike general object detection, COD is a more challenging task because the target boundaries are vague and the location is difficult to determine. In this paper, we propose a novel COD framework, which consists of two main components, namely, Neighbor Connection Mode (NCM) and Hierarchical Information Transfer (HIT). NCM aggregates the features from the neighboring layers of the encoder network to enhance the complementation of various level information. Our NCM not only reduces the burden of dense connection that consumes a lot of computing memory and redundant features but also weakens the phenomenon of the long-term transmission of context. We also propose a HIT module to transfer the features of different dilated rates inside each level hierarchically, which expands the receptive field of each branch and enhances the relationship between different features. Our method accurately detects camouflaged objects by considering full level information and a large receptive field. The experiments on three COD datasets show that our model achieves state-of-the-art performance.

Will they ride them back? User behavior on public bikesharing schemes: Case study of Hangzhou, China

In order to study user behavior to support the management of Station-based Bikesharing Systems (SBS), Free-floating Bikesharing Systems (FBS), and the whole public bikesharing system, this study scrutinized factors that influence bikeshare-user patterns of one-way trips or round trips and examined the use frequency characteristics including both systems. Based on the data collected by questionnaires, descriptive analysis shows that the user profile of education background, private vehicle ownership, riding days during a week, departure time of day, trip type, mode transfer and service satisfaction for both systems is similar. To detect the factors associated with cycling for a round-trip versus one-way, this study uses step-wise logistic regression analysis to compare the difference between the targeted users. Putting samples of the two systems together and applying an ordinal logistic regression model, the outcomes show that as the increase of use frequency, trips are more likely to be one-way trips, generated by SBS users. They are likely to work at state-owned enterprises, having travel purposes more likely related to family or personal affairs rather than work affairs and owning cars. Finally, recommendations are given for operators of both schemes as well as government organizations responsible for supervising these schemes.

Tunable narrow transparency windows induced by the coupled quasi-guided modes in borophene plasmonic nanostructure

A grating-assisted triple-layer continuous borophene sheets structure is presented to investigate the phase-coupled plasmon-induced transparency (PIT) effect at the near-infrared communication band. In the proposed structure, the diffraction grating is utilized to couple the normal incident waves, which excites the quasi-guided mode in triple-layer continuous borophene sheets. Compared to the patterned structure, the requirement of complicated processing techniques and extra doping configurations for tuning carrier density can be avoided by using the continuous borophene sheet. Additionally, the narrower transparency windows are shown in the spectral responses via the phase coupling between two detuned quasi-guided modes with high quality factors. The transparency windows can be efficiently tuned by adjusting the carrier densities in borophene sheets or the separation distances between the borophene sheets. The analytical results based on temporal coupled mode theory and transfer matrix method are consistent with the numerical simulations via finite-difference time-domain calculations. The proposed scheme provides the promising design of a tunable PIT component that is compatible with optical communication technology.

Influence of the Number of Parallel Joints on the Dynamic Mechanical Properties of Rock-Like Features

The number and distribution of joints in rock are closely related to their physical and mechanical properties. In this paper, given the propagation law of explosive stress waves in jointed rock during rock blasting and the influence of joints on dynamic mechanical properties and crushing energy dissipation of rock, parallel joints are simulated in the construction of concrete specimens using a mica sheet. The discrete Hopkinson test device is used to perform the impact test, which is based on the three-wave and fractal theory. Under dynamic load, the fluctuation characteristics, failure mode, fractal dimension, and energy dissipation transfer law of rock-like specimens with various parallel joints are studied in detail. The results show that the overall failure of the specimen becomes more severe with the increase of parallel joints, and the failure mode is changed from the conjugate shear failure of the complete specimen to the edge collapse failure with joints. Thus, as the number of joints increases, the static strength decreases, and the degree of reduction is positively related to the number of joints. With the number of joints, the changing trend of enhancement factor increases first and then slows down. Compared with nonjointed specimens, the transmission coefficient of 1-3 jointed specimens is decreased by 0.22, 0.05, and 0.17, respectively. The dimension of the specimen D f is positively correlated. Under the synonymous impact pressure of 0.35 MPa, the corresponding fractal dimension is increased from 2.27 to 2.42. The crushing energy consumption density, transmission coefficient, and dynamic compressive strength σ d of the specimen are significantly negatively correlated, and the crushing energy consumption density of the specimen decreased from 0.82 J/cm3 to 0.28 J/cm3.

The Effect of Public Transportation Management to the City Planning in Medan

The movement of human flows, vehicles, and goods leads to various interactions. Almost all interactions require us to travel. Therefore, the result is the movement of traffic flows. In general, transportation planning makes interaction as easy and efficient as possible. Transportation management is an integral part of city planning. The city plan will cause many traffic problems without considering the transportation patterns. Good urban transportation systems should make public transportation the primary means of mobility; however, people are still reluctant to use public transport in developing countries such as Indonesia. There are still many people who prefer to use private transportation. This study aims to analyze the effect of public transportation management on city planning in Medan. The samples of this research are all the users of public transportations at Medan who are 400 people. The collection methods are coming interviews, distribution of questionnaires, and documentary studies. The data analysis method used in this study is the multiple regression linear analysis. The research results showed that simultaneous transportation encompasses means of transportation, transport infrastructure, service quality, accessibility, public transport routes, and the integration of modes. These significantly affect city planning in Medan, with mode integration being a partially dominant factor of influence. The services of different ways of transport should be integrated with an easy and convenient mode transfer scope.

Detection of Traffic Pattern Based on Fuzzy Clustering and Wavelet Analysis Model at Different Signaling Positioning Frequencies

Signaling positioning technology provides a new opportunity to understand an individual’s travel characteristics. In recent studies, the travel parameters obtained are mainly macroscopic travel information. However, extracting detailed trip chain information, such as the trip mode and mode-switching time point, remains a challenge. Furthermore, because of the iterative development of wireless networks, existing communication operators usually store different frequencies and accuracy (2G/3G and 4G) of signaling data simultaneously, making the refined identification of travel information more difficult. Therefore, this paper proposes a new method. First, we use the shortest distance algorithm to match the signaling data with the road network. Second, a wavelet transform modulus maximum (WTMM) algorithm is proposed to divide multimodal travel trajectories into single-mode trip segments; thus, spatiotemporal information related to mode transfer can be obtained. Finally, an unsupervised fuzzy kernel c-means clustering (FKCM) algorithm is proposed to distinguish travel modes. As comparison data, smartphone GPS and travel log data are also collected to analyze the detection result and improve the method. The identification errors of mode-switching time points at different frequencies are all less than 360 s. The average correct rate of traffic mode identification for 2G is 65.1%, and the average correct rate of traffic mode identification for 3G is 78.2%. 4G intensive cellular positioning data has a significantly better recognition effect than low-frequency data; the average trip mode detection accuracy reaches 89.6%, and the mode-switching time point detection errors are within 300 s.

Evaluation of TOD rail station connection design based on analytic hierarchy process and cloud model

It is necessary to carry out an integrated connection design for the rail station area to promote the development of the transit-oriented development (TOD) mode. There is lack of an evaluation index system that comprehensively considers the characteristics of TOD. Based on the characteristics of TOD mode and passenger transfer satisfaction, we propose an evaluation index system for the design of the connections between TOD rail stations and each of the three transportation modes including pedestrians, conventional buses and non-motorized vehicles, respectively. We formulate the grading standards for quantitative and qualitative indicators through literature research and questionnaire survey, respectively. In order to obtain relatively objective and comprehensive evaluation results, we propose an evaluation method combining analytic hierarchy process (AHP) and cloud model, which is superior to single evaluation methods. Finally, Nanjing Xinjiekou rail station is selected as a case for the application of indexes and the evaluation method. The evaluation results about the connection levels of the three transportation modes are medium, good, and medium, which basically conform to the characteristics of central commercial stations.

Multimode Features of CIPNLMS-MFX Controlled Single-Phase PV System With Finite State Machine Based Islanding/Synchronization Under Grid Outage

This article presents multimode features of a single-phase photovoltaic (PV) system controlled through a combined improved proportionate-normalized least mean square with modified filtered-X (CIPNLMS-MFX) technique. This system waves off from using the battery storage and successfully operated in standalone mode to achieve the load demand even under the grid outage. The CIPNLMS-MFX based current control technique includes asymmetry parameters and the optimized selection of these parameters provides fast convergence speed, good steady-state response, and improved power quality at nonlinear loads. This PV system is also supported with the synchronization and mode transfer control so that the PV system has autonomous operation under outage and recovery of the grid without disturbing the supply across the domestic loads. A fast detection of a dual cascaded generalized integrator synchronization/islanding structure is presented to evaluate fundamental grid voltage, phase angles, and change in frequency. This structure is robust against the abnormal conditions at the utility grid. The experimental results show that presented CIPNLMS-MFX, DCGI, and finite state machine based logic for islanding/synchronization techniques achieve considerably good performance under various operating scenarios, e.g., outage/ restoration of grid power, varying nonlinear loads, and outage of solar power.

Parameters optimization and performance evaluation of multiple tuned mass dampers to mitigate the vortex-induced vibration of a long-span bridge

Vortex-induced vibration(VIV) is one of the primary dynamic problems of long-span bridges, which affects the safety and serviceability of bridges. The control and mitigation of VIV is a hotspot to researchers. Multiple tuned mass dampers(MTMD) consist of a set of tuned mass dampers(TMD) with varied frequencies and damping ratios, which is a common method for vibration control of structures. In this study, a concept of complex effective mass is proposed, which can entirely represent the dynamic effect of MTMD on bridges, and a derivative-based MTMD optimization process for VIV control of long-span bridges is presented. The VIV mitigation of a six-span continuous steel box-girder bridge is used to analyze the performance and mechanism of MTMD from the aspects of frequency domain and time domain. Optimal parameters of MTMD for suppressing VIV are obtained by the proposed algorithm. The results indicate that MTMD can significantly reduce the displacement amplitude of the beam due to VIV, and the performance of MTMD is better than that of single tuned mass damper(STMD) with the same mass ratio. The optimal performance of MTMD is independent of the mass distribution of the sub-TMDs. Moreover, the damping ratio of MTMD is much lower than that of STMD, but it can still help the vibration of the primary structure to decay faster. Complex mode theory and transfer function theory are used to explain this phenomenon. It indicates that the performance of MTMD does not depend on its damping ratio but is due to the phase interference between complex modes, and a one-way energy barrier between the bridge deck and MTMD can be formed, which prevents the transfer of vibration energy from MTMD to the primary structure after unloading. Finally, the stroke of MTMD in the control of long-span bridge VIV is analyzed, and a simplified formula is proposed.

Utility intertie multi‐photovoltaic‐inverters‐based microgrid control for solar rooftop

The solar photovoltaic (PV)-based microgrid is one of the most ideal renewable energy resources. This paper presents a utility grid intertie multi-PV-inverter-based microgrid (MG) control for the solar rooftop application. The main and ancillary voltage source converters (VSCs) DC links are assimilated with PV arrays of independent maximum power point tracking (MPPT) algorithms for the economical and efficacious single-stage configuration. At the point of common coupling (PCC), parallel VSCs arrangement increases the MG's power rating with distinctive local loads. In normal circumstances, the current control methodology is employed by the main VSC under the grid-interactive mode. Conversely, in some grid contingency conditions under the isolated mode, its control transfers to the voltage control, which regulates the frequency and the voltage at PCC and acts like a grid-forming inverter. The ancillary VSC operation is implemented with the current control algorithm. The main VSC supplies the active power towards the grid and accomplishes the load requirement, whereas the ancillary VSC retains its load demand in a grid-interactive mode and also regulates the load requirement in an islanded mode of operation. The utilization of feed-forward components for PV arrays powers in the VSCs current control techniques improves the MG dynamic performance. The seamless mode transfer performance of the main VSC is implemented via a power electronics switch. The MATLAB software is used to model a microgrid and its performance is analysed via RT-LAB in real time through the OPAL-RT (OP4510) controller for various scenarios, that is, varying solar insolation, load alterations and unbalanced non-linear loads. The utilization of the modified Kwong's algorithm-based current control enhances the power quality such as harmonics current elimination and improvement in the power factor. The voltage profile of PCC voltages is enhanced via using a modified Kwong's algorithm-based filter in the voltage controller. The modified Kwong's algorithm has fast convergence, reduces misadjustments and gives very good performance compared to the least-mean-square (LMS) and Kwong's approaches. The total harmonic distortion (THD) of grid currents and PCC voltages THD in an isolated mode is found according to the limits of the IEEE-519 standard.

Study on heat transfer characteristics of single-layer double-row pulsating heat pipe

The structure and inclination angle of a pulsating heat pipe are critical factors influencing the heat transfer performance and operation mode. In this work, a single-layer double-row pulsating heat pipe is designed, and the start-up and heat transfer characteristics of pulsating heat pipe at limit angles (0?, 90?, and 180?) are experimentally investigated. Also, the operation mode and heat transfer characteristics are studied through infrared imager and temperature profiles. The study highlighted that the pulsating heat pipe has excellent operation characteristics in the limit angle. When the inclination angle is 0?, the double-row structure improves the start-up performance and at 90? inclination, the pulsating heat pipe starts the fastest, and the heat transfer resistance keeps the smallest in the whole test. When the inclination angle is 180?, the pulsating heat pipe has the best thermal sensitivity but weak working fluid-flow capacity during operation.

Unified Control Scheme of Grid-Connected Inverters for Autonomous and Smooth Transfer to Stand-Alone Mode

As one of the approaches for a grid-sustaining inverter, the inverter should cover not only grid-connected (GC) mode but also stand-alone (SA) mode for power supply to local loads; therefore, there are separate control loops for each mode. In order for an uninterruptible power supply to the local load, it should be seamless to change from GC mode to SA mode. This carries two types of issues. One is a transient state caused by switching the control loops. The other is an uncontrolled state during the time interval between a grid failure and its detection, called clearing time. These can lead to unstable voltage for the local load. Hence, a smooth and autonomous mode switching method is required even if the fault detection is late. Existing mode transfer methods considering both the issues have been accompanied by a slow dynamic response, additional sensors, restriction of adopting filter, or controller complexity due to third-order plant. To overcome them, in this article, a control scheme realized by a unified control loop is proposed for smooth and autonomous mode switching with a novel antiderailing control. Furthermore, the proposed control scheme can achieve a high bandwidth for the output power control in GC mode because it is based on controlling the current flowing the inverter-side inductor, and both filter types, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> , can be adopted. To validate the proposed concept, simulations and experiments were conducted. The results show that the proposed control scheme can be used to achieve autonomous and smooth mode transition even under reactive power reference and reactive load conditions.

Chiral/directional mode transfer based on a tunable non-Hermitian system

Exceptional points (EPs) of non-Hermitian systems are the degeneracies of both the eigenvalues and eigenvectors, which have led to a series of novel and counterintuitive physical effects. Adiabatically encircling the EP in parameter space could lead to chiral mode transfer in coupled waveguides. However, the fixed refractive index distribution in existing devices will confine the parametric loops and lay great limitations on the performances of the mode conversion. Herein, we theoretically propose a non-Hermitian system based on refractive index modulation of coupled liquid crystal (LC) waveguides, which allows for encircling the EP with tunable loops. As a result, chiral mode transfer is achieved with optimized performances at wide telecommunication wavelengths, including a high transfer efficiency (&gt;80%). Moreover, the dynamic modulation of the refractive index enables a directional mode transfer which is solely dependent on the modulation direction, even with non-closing evolution routes. The tunable non-Hermitian system serves as a versatile platform for realizing tunable mode transfer processes with optimized performances, showing great promise for developing multifunctional non-Hermitian nanophotonic devices.

Chiral mode transfer of symmetry-broken states in anti-parity-time-symmetric mechanical system

Non-Hermitian systems with parity-time (PT) symmetry reveal rich physics beyond the Hermitian regime. As the counterpart of conventional PT symmetry, anti-parity-time (APT) symmetry may lead to new insights and applications. Complementary to PT-symmetric systems, non-reciprocal and chiral mode switching for symmetry-broken modes have been reported in optics with an exceptional point dynamically encircled in the parameter space of an APT-symmetric system. However, it has remained an open question whether and how the APT-symmetry-induced chiral mode transfer could be realized in mechanical systems. This paper investigates the implementation of APT symmetry in a three-element mass–spring system. The dynamic encircling of an APT-symmetric exceptional point has been implemented using dynamic-modulation mechanisms with time-driven stiffness. It is found that the dynamic encircling of an exceptional point in an APT-symmetric system with the starting point near the symmetry-broken phase leads to chiral mode switching. These findings may provide new opportunities for unprecedented wave manipulation in mechanical systems.

EVALUASI FASILITAS BAGI PENYANDANG DISABILITAS DI STASIUN YOGYAKARTA

Yogyakarta Station is a railway station located in Yogyakarta City. As a transportation mode transfer point, the station must be inclusive for all train passengers, including passengers with disabilities. An inclusive railway station will be accomplished by providing station facilities that accommodate accessibility for passengers with disabilities. This study aims to evaluate the facilities for passengers with disabilities at Yogyakarta Station. By understanding the evaluation, railway operators and governments will create specific improvements that would make the station more inclusive. The facilities are following the Minister of Transportation Regulation Number PM 98 of 2017 concerning Providing Accessibility to Public Transportation Services for Service Users with Special Needs. This study uses the IPA (Importance Performance Analysis) method obtained through observation and questionnaires. The result shows that based on 15 (fifteen) facilities evaluated, all facilities are available in Yogyakarta Station except the guide block to the counters and toilets, information in Braille letters, ticketing counters/special ticketing counters, and information/customer service rooms which accessible easily. In addition, based on the IPA method, improving facilities for passengers with disabilities at Yogyakarta Station should be prioritized for ready-to-use wheelchair facilities, access to and from passengers in multi-story buildings, and toilet access.

Flight Testing Automatic Landing Control for Unmanned Aircraft Including Curved Approaches

Automatic landing of aircraft is a challenging guidance and control task that requires multiple feedback loops and a precise sequence of actions. Increasing operational flexibility and reducing the dependence on external infrastructure are key challenges for future unmanned aircraft. Usually, an aircraft performs the final approach on a straight line. This paper contributes a complete automatic landing controller capable of using three-dimensional curved approach paths all the way until touchdown. The controller consists of a nonlinear guidance law that steers the aircraft along a predefined spline path, various single-input–single-output control loops for rate and attitude control, and a robust multivariable flare controller. This flare controller ensures a three-point landing, i.e., simultaneous touchdown of all three wheels. Further, practical issues such as bumpless mode transfer and anti-windup compensation are considered. The controller is evaluated in multiple flight test experiments. Both the crabbed approach and the sideslip technique are demonstrated on several different approach paths, such as a steep curve and a helix. These paths are particularly challenging, because the flare maneuver is performed while the aircraft is in a turn. The controller is shown to reliably land the aircraft on an unpaved runway with high precision.