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Novel designs of paper-based bandstop frequency-selective surfaces (FSSs) are presented in this article. The characteristics of the paper-based honeycomb structure are investigated first. One folded dipole resonator with first-order bandstop response is analyzed and further printed on the sidewalls of the honeycomb structure accordingly. A second-order response with two cascade FSSs is proposed with controllable bandwidth by the coupling coefficient of the resonators with the aid of the equivalent circuit model. Two paper-based FSS samples were fabricated and measured to demonstrate the validity of the proposed design strategies. Benefiting from the merits of lightweight and strong mechanical properties, the proposed paper-based FSS is a potential candidate for application in radar systems and aircraft. [ABSTRACT FROM AUTHOR]

The oil-impregnated paper, which is the major section in converter transformer, plays a considerable role in the reliability and safety of power grid. However, the insulation degradation will be accelerated by the accumulation of charges that are on the surface of oil-impregnated paper. Therefore, the operating overvoltage occurs and irremediable damage will appear. Direct fluorination is an effective method of modifying the chemical components of polymer matrix so as to have effects on the surface characteristic of the insulating material without reforming the bulk properties. In this research, for studying effects of fluorination on charge behavior on the surface of oil-impregnated paper under the application of DC and impulse voltage, the F2/N2 compound, which the volume fraction for the F2 gas occupied 10 % and the pressure was 0.05 MPa in a reaction kettle for 5, 30 and 60 min respectively, was applied. Meanwhile, the chemical bond groups and the surface morphology of the fluorinated specimen were tested. Besides, the DC voltage amplitude was 4 kV and the applied time was 4 min. The impulse frequency was 500 Hz and the impulse voltage amplitude was 1, 2, 3 and 4 kV, respectively. The charge properties under various situations were investigated. From the research under the application of different fluorination time, impulse voltage amplitudes and polarities, conclusions can be drawn that, fluorination has significant effects on the chemical structure properties and surface characteristic of oil-impregnated paper. Furthermore, the initial potential can be reduced and the decay process of surface charge can be accelerated with different fluorination time increasing from 0 to 30 min. Nevertheless, the tendency is the opposite when the fluorination time continuously extends from 30 to 60 min. The trap distribution also exhibits alternation through the fluorination. [ABSTRACT FROM PUBLISHER]

An oil-paper insulation system which will withstand DC voltage under normal conditions is a key component of converter transformers as well as high voltage direct current (HVDC) bushings. When the system changes its state, operating overvoltage appears. This kind of overvoltage will consequently affect the application of oilimmersed facilities and the safety of entire grid. Therefore, this paper studies the charge coupling behavior of double-layer oil-paper insulation under DC and pulse voltages. From the research of different pulse voltage amplitudes, pulse numbers and polarity, conclusions can be drawn that, with the increase of the pulse voltage amplitudes, DC and pulse voltages in the same polarity cause the absolute value of the initial surface potential to decrease and then rise; while in different polarities, the charge with the same polarity as the pulse voltage increases. Furthermore, for the same pulse voltage, the absolute initial value of the DC voltage applied in the same polarity is higher than that in different polarities. Considering the pulse number effect, it is obvious that the initial value increases with the increase in the pulse number, and then reaches saturation. Also, with the increase in pulse number, the decay rate decreases and thus the charge is slowly dissipated. From the tdV/dt and the decay time curves, the peak value increases with the increase in the pulse number, while the characteristic time varies by the polarity of the DC and pulse voltages. [ABSTRACT FROM AUTHOR]

This paper presents a digital gyroscope interface system for high-frequency bulk-acoustic-wave (BAW) gyroscopes with in-run automatic mode-matching (AMM) capability. The presented work demonstrates the design and implementation of the dual-mode (DM) operation architecture on a flexible digital platform, which allows for low-cost rapid development and evaluation of new functions and architectures. Two prototype silicon BAW gyroscopes are tested on this platform using the proposed system to verify the advantages of the DM architecture. The AMM in DM showed below 4-ppb mode split accuracy and fast converge time without overshoot or oscillation. The DM operation with in-run AMM substantially reduced the bias drift of the gyros, leading to significantly lower rate random walk (RRW) compared to conventional single-mode (SM) operation. The performance repeatability and stability over the temperature of the DM gyro system are characterized, showing as high as $50\times $ improvement compared to the SM architecture. [ABSTRACT FROM AUTHOR]

In this paper, an inkjet-printed electromagnet-based touchpad employing spiral resonators is proposed. The proposed touchpad is fabricated by a direct patterning method using an inkjet printer with a conductive silver nanoparticle ink. The conductive patterns are easily printed on a paper substrate and sintered for achieving good conductivity. The proposed touchpad is composed of two spiral resonators that resonate at 0.94 GHz ( f1 ) and 1.83 GHz ( f2 ), respectively. When the first resonator is touched, f1 decreases from 0.94 to 0.81 GHz because of electromagnetic (EM) coupling between the finger and the spiral resonator. Similarly, when the second resonator is touched, f2 decreases from 1.83 to 1.55 GHz. Owing to the EM coupling distance between the spiral resonator and the finger, the frequency changes although the finger does not reach beyond a height of 1.27 mm on the spiral resonator. The performance of the proposed touchpad is validated using simulation and measurement results. [2016-0035] [ABSTRACT FROM AUTHOR]

This paper explores the patterns of knowledge production of science and engineering from catching-up via overtaking to the achievement of leadership in global industries. In particular, it examines the depth and direction of knowledge production with proxy variables of patents and bibliometric data of a latecomer firm. Moreover, it explores the changing patterns of knowledge sourcing in the firm during the transition from catch-up to forging ahead and with specific references to the experience of Samsung Electronics Company. This study shows that the patterns of scientific and engineering activities increased as the firm proceeds to the forging ahead period, the patterns of knowledge sourcing evolved in the direction of increasing importance of the domestic knowledge base, and the collaborative partners for generating knowledge changed as the firm's capabilities were enhanced to approach cutting-edge technologies. This paper illuminates the importance of intraorganizational capabilities and domestic knowledge bases to advance a latecomer firm's knowledge generating capabilities into a stage of forging ahead. [ABSTRACT FROM AUTHOR]

This paper analyzed the flux characteristics of a single-phase tubular switched reluctance linear motor (TSRLM) based on magnetic equivalent circuit (MEC) method. The single-phase TSRLM is divided into five different parts, which are the teeth of the stator, the yoke of the stator, air gap, the teeth of the mover, and the yoke of the mover. The reluctance of every part is expressed in analytical formulas at five special mover positions. The flux linkages at five special mover positions are calculated by magnet tube method and Gauss–Seidel iteration method which takes the saturation into consideration. A high-order Fourier series method is used to map the nonlinear relationship between flux linkage, current, and mover position with the flux linkage data calculated by the MEC method. The calculated flux linkage is consistent with 3-D finite-element method and experimental results. The dynamic and static performance of the simulation utilized with MEC method is consistent with those in experiments, which verifies the accuracy of the MEC method proposed in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes a metamaterial inspired radio frequency touchpad sensor system based on two split ring resonators (SRRs) realized on a Rogers/Duroid 5870 with 2.33 dielectric constant = 2.33, loss tangent = 0.0012, and thickness = 0.8 mm. The touchpad consists of two SRRs resonating at $f_{1} = 2.74$ GHz and $f_{2} = 3.86$ GHz. When a finger is placed on SRR 1, $f_{1}$ changes from 2.74 to 2.57 GHz due to electromagnetic coupling between the SRR and the finger, and similarly, $f_{2}$ changes from 3.86 to 3.76 GHz. The proposed touchpad system can detect a finger wearing a glove, in contrast to capacitive touchpads utilized in contemporary smart phones. We demonstrated 56- and 49-MHz frequency shifts for $f_{1}$ and $f_{2}$ , respectively, with 1.66-mm total thickness (0.69-mm-thick photo paper and 0.97-mm-thick glass slide). [ABSTRACT FROM AUTHOR]

For patients who need lower-limb kinetism rehabilitation training, this paper proposes an effective data-driven approach seeking the design of 1-degree-of-freedom (DOF) six-bar rehab mechanism through gait prediction by body parameters. First, gait trajectories from 79 healthy volunteers are collected along with their body parameters. Then, the normalized gait samples are clustered and regressed into a limited number of representative trajectories with K-means algorithm, and the cluster index is recorded as the label for each trajectory. Next, a genetic-algorithm-optimized support vector machine method is adopted to establish a classifier for the trajectories, obtaining the correspondence between body parameters and cluster labels of gait trajectories. As a result, once a group of body parameters are input into the classifier, the suitable gait trajectory can be predicted for the specific patient. A GA-BFGS algorithm is developed for 1-DOF six-bar mechanism synthesis and a GUI design software is presented that shows how the data-driven design process is realized. The novelty of this paper is using clustering and prediction technique to accomplish the patient-mechanism matching, so that simple, low-priced 1-DOF mechanisms could be adopted for large number of various patients without expensive customized design for each individual. In the end, a gait rehab device design example is provided, and a prototype device driven by a constant speed motor is presented, which illustrates the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

The maximum efficiency point of an inductive power link depends on its load power consumption and the distance between the transmitter and the receiver. Matching networks (MNs) and adjustable ac–dc converters have been proposed in the literature as a means to achieve and track this maximum efficiency point. Most of the published papers in inductive power transmission only use one of these two methods without considering a joint design. In this paper, we analyze and compare both methods proposing a general joint design which exploits the advantages of each method. A proof-of-concept system was developed following the proposed flow, built and tested. This system, with a regulated output voltage, presents improvements in measured efficiencies of up to 80% (from 9.2% to 16%) at the largest distances, thus maximizing the distance range. The same approach can be used to maximize output dc voltage, instead of the link efficiency. The proposed system using our designed MN achieved a maximum output voltage that was 90% higher (from 1.36 to 2.59 V) than the case where only a step-up converter was used. [ABSTRACT FROM AUTHOR]

This paper proposes a new coupling matrix synthesis technique called the coupling matrix compression technique, which focuses on reducing the dimension of the $N+2$ coupling matrix. The presented coupling matrices can be compressed, and this technique can be used to design dual-mode resonators for high-isolation dual-band filters. One dual-mode resonator is represented as two closely coupled resonators when using this technique. The formulae for resonant frequencies and $\omega _{m}$ in dual-mode theory are also derived in this paper. A dual-mode embedded hairpin resonator is designed and analyzed using this technique, and a dual-band filter using the proposed resonators is designed and fabricated to validate the proposed technique. [ABSTRACT FROM AUTHOR]

This paper focuses on analytical methods of a finite-element method (FEM)-based edge heating system. The edge heating system plays a role in maintaining the temperature in the hot rolling process of carbon steel. Carbon steel moves along the production line and maintains the temperature by the edge heating system in the process. Power-of-the-edge heating system is transmitted to carbon steel during the process. Eddy currents are generated in carbon steel by Faraday’s law of electromagnetic induction, and eddy current loss serves as a heat source to increase the temperature. Thus, there is a need for accurate electromagnetic-field analysis and thermal analysis because the eddy current path generated in carbon steel greatly affects the heat distribution in carbon steel. This multiphysics analysis requires high reliability. Accordingly, this paper presents a coupling analysis method using an FEM-based coordinate mapping method as a more accurate analytical method. This paper also established an analytical approach to the edge heating system using the ductility analytical method of this coordinate mapping method. [ABSTRACT FROM AUTHOR]

With the rapid growth of renewable energy and power electronic loads, voltage source converters (VSCs) have been commonly applied in different VSCs-based power systems, which also bring in stability issues due to their power electronic characteristics. The impedance-based stability theory and corresponding reshaping method can be used to analyze and solve system stability issue. However, dc stability issue in VSCs-based power systems becomes more complicated when considering ac/dc coupling relationship. This paper proposes an improved reshaping control strategy based on the detailed impedance model considering grid impedance and control delay. The influence of grid impedance, control delay and control parameters of VSC on dc stability are further analyzed to identify the cause of potential resonance risk. The proposed impedance reshaping method considers the trade-off between stability improvement and control performance, and compensates the impacts of grid impedance and control delay at the same time. The validity of stability analysis and reshaping method is further verified through the simulation and experimental results. [ABSTRACT FROM AUTHOR]

To research the impact of temperature-dependent characteristics of windings and magnets on the electromagnetic power loss and thermal properties of high-speed (HS) interior permanent magnet synchronous machines (PMSMs), an electromagnetic-thermal bi-directional coupling method (BDCM) is proposed for water-cooled HS PMSMs considering the assembling gaps between the motor components in this paper. The electromagnetic power loss is calculated by 3-D transient finite-element method and loaded into the 3-D temperature field according to the actual loss distribution, and the materials’ properties are in turn updated according to the temperature distributions. The loss and temperature calculation results of a 15kW HS amorphous metal PMSM are calculated by two different coupling methods in the conditions of the rated-load sinusoidal supply and converter supply, and compared with the measured results in the case of converter supply. The results obtained by the BDCM are more consistent with the experiment results, verifying the superiority of the proposed analyzing method in improving the calculation accuracy of motor loss and temperature rise. In addition, the applicable conditions of the proposed method are also summarized in the paper. [ABSTRACT FROM AUTHOR]

This paper proposes a wideband and low direct-coupling tapered slot antenna (TSA) using electromagnetic bandgap (EBG) structure. We name this antenna the EBG-TSA. In some near field imaging systems including ground penetrating radars, a number of TSAs are arranged into an array with very small spacing in order to realize high-resolution imaging without synthetic aperture processing. Then, the direct coupling among TSA elements is nonnegligible and harmful. In this paper, we show that the EBG structure is effective in reducing the direct coupling with its stopband, which prevents an electromagnetic wave from propagating in a specific frequency band. Our EBG-TSA reduces its direct coupling by 3 dB or more in a wide band. We also find that the tapered EBG structure area assists the radiation by guiding the fin current flow two-dimensionally along the tapered slot so that the boresight gain increases. The EBG structure contributes to both the direct coupling reduction and the boresight gain enhancement. [ABSTRACT FROM AUTHOR]

In this paper, an inner ultrathin oxide metal–oxide–semiconductor (MOS) capacitor is fabricated with another outer MOS-gate ring as a coupling controller. Capacitance–voltage characteristics of inner MOS capacitor show that the excess minority carriers supplied from the outer MOS-gate ring can efficiently change the inner capacitance (${C} _{\text {inner}}$). It is observed that outer MOS-gate ring under the conditions at floating and at ground has quite different coupling effects on ${C} _{\text {inner}}$ when the inner MOS is biased at 1 V. Comparing to ${V} _{\text {outer}} = \text {floating}$ , ${C} _{\text {inner}}$ reduces significantly when ${V} _{\text {outer}} = {0}$ V at 1k Hz. The transient behavior of ${C} _{\text {inner}}$ as ${V} _{\text {outer}}$ changes from 0 V to floating is long enough to read, and the difference of two capacitance values can be regarded as two states. As a result, a two capacitance states operation is proposed for possible memory application. Based on the experimental results, the possible memory cell configuration is designed. Comparing to the present emerging memories, since the two states in this paper are in conditions of floating and 0 V, ultralow power is consumed, which is believed a promising concept for future memory application. [ABSTRACT FROM AUTHOR]

This paper presents an approach for the time domain statistical simulation of field-to-wire coupling model with uncertain wire position in traverse direction. The parameters of governing equations of field-to-wire coupling model about the wire position are expanded to the augmented governing equations by using the generalized polynomial chaos technique with normalized orthogonal basis functions. And the coefficients of the polynomial chaos expansions are solved by combining with the stochastic Galerkin method. However, the solution of augmented governing equations is a complex problem. Therefore, a new finite-difference time-domain (FDTD) algorithm based on the implicit Wendroff difference format is proposed to solve the governing equations, and the general iterative equations are given in this paper. The proposed methods are verified by a field-to-wire coupling model. The effectiveness and advantages of the new FDTD algorithm and the uncertainty analysis method based on generalized polynomial chaos technique are verified, which are achieved by comparing with the conventional leapfrog fashion FDTD algorithm and the Monte Carlo technique, respectively. [ABSTRACT FROM AUTHOR]

This paper probes deeper into the impact of specific investment on the performance of R&D collaboration through investigating the relationships of both total specific investment and specific investment asymmetry to the performance of R&D collaboration and by examining the mediating effects of cooperative and competitive behaviors on the relationships. Drawing on the data of 140 dyadic R&D collaboration, this paper finds that total specific investment and specific investment asymmetry have different effects on the performance of R&D collaboration, and cooperative and competitive behaviors are the conduits through which specific investment works. These findings not only enrich our knowledge on the linkage of specific investment to the performance of R&D collaboration, but also advance our understanding of the implications of specific investment and the determinants of the performance of R&D collaboration. In addition, this paper responds to the call for testing antecedents and consequences of cooperative and competitive behaviors in collaboration and thereby contributes to research on these behaviors. [ABSTRACT FROM AUTHOR]

Few of the challenges with development of a single on–board motor for direct–drive electric vehicles include high torque density and low torque ripple. Therefore, in this paper, a 36–slot, 34–pole consequent pole six–phase permanent magnet synchronous machine (PMSM) has been optimized to address the aforementioned challenges for direct–drive application. Existing literature on optimization processes that rely solely on finite element models are restricted to three–phase machines only and also take longer computation time. Therefore, this paper proposes a novel optimization approach based on supervised machine learning for six–phase PMSM. In this approach, a non–conventional extended dual dq–frame model that accounts for higher order space harmonics in inductances and flux linkages has been developed and used for accurate computation of average torque and torque ripple of six–phase PMSM. Using the performance characteristics obtained from the extended dual dq–frame model for a set of initial design candidates, support vector regression algorithm is employed for supervised machine learning and increasing solutions in the design space. Furthermore, pareto front is used for selecting optimal machine models with maximum torque density and reduced torque ripple. Multi–objective trade–offs and comparison of initial and optimized designs based on average torque, torque ripple, efficiency and cost are performed. [ABSTRACT FROM AUTHOR]

This paper proposes an intelligent modeling and optimization method to set up the smart energy hub model for the multiple energy system and optimize the operation of its associated energy hub model automatically. The core idea of the proposed method is to divide the complex energy hub model into several simple energy hub models. In this paper, the proposed computerized algorithm, which is applied to the smart energy hub model division, includes an energy loop intelligent searching method, a real nodes arrangement method, and a virtual nodes insertion method. One case study for the multiple energy system of a residential district in Guangzhou city is performed to validate the effectiveness of the proposed method. Compared with the traditional calculation method, the proposed method guarantees global optimal operation decision for the whole multiple energy system and the computational burden is significantly reduced. [ABSTRACT FROM AUTHOR]

Conventionally, for a tubular permanent magnet synchronous linear motor (TPMSLM), adopting a modular structure can effectively reduce the detent force; however, the thrust density is sacrificed via the large proportion of the flux barrier to the total primary component volume. To overcome this disadvantage, this paper proposes a novel modular TPMSLM, in which the unit primary component adopts the large slot structure containing several coils. Focusing on this motor, research on the flux linkage characteristic is performed to obtain the design principle, and then the detent force is analyzed and suppressed by reasonable design of end teeth. First, the flux linkage characteristics of the unit motor and the whole motor are investigated. Variation rule of the coil flux linkage affected by the end tooth is discussed, and the principle of realizing three-phase balance for the whole motor flux linkage is elaborated. Moreover, the principle of the detent force suppression is verified and the detent force is further suppressed through the end tooth design. Finally, a prototype is developed. The back electromotive force and the detent force were tested, which verified the effectiveness of the novel modular TPMSLM proposed. [ABSTRACT FROM AUTHOR]

This paper studies on polarization beam splitter (PBS) in high-index-contrast waveguides based on sinusoidally driven directional coupler (SDDC), and offers new insights to realize compact and low-loss PBS with high fabrication tolerance. The PBS based on SDDC has advantage that power shift to an adjacent waveguide can be suppressed or totally banned by satisfying coherent destruction of tunneling (CDT) condition. However, in practical implementation, the PBS based on SDDC has trade-off relation between cross-talk of TE-like wave and loss of TM-like one. This paper investigates characteristics of the SDDC numerically, and shows possibility that cross-talk and loss can be suppressed, and small footprint can be achieved by position shift of DC-gap maintaining high fabrication tolerance. [ABSTRACT FROM AUTHOR]

Three-variable chaotic synchronization has been implemented based on DNA chemical reaction networks (CRNs) in previous works. However, it is still difficult to realize the encryption and decryption of continuous signals. A scheme of secure communication is proposed based on chaotic coupling synchronization by DNA CRNs in this paper. Firstly, the CRNs of two three-variable chaotic systems are constructed using bimolecular representation. Secondly, according to the design principle of the coupling term and the theory of stability, the CRNs of the coupling term are designed to realize the synchronization of two chaotic systems. Finally, the oblique wave, square wave, and staircase wave signals are added into chaotic systems to realize encryption and decryption. The dynamic behavior of a three-variable chaotic system is verified by Visual DSD and MATLAB software. The synchronization proof and the experimental results of encryption and decryption are given. The results indicate that the proposed secure communication scheme is effective. This paper provides an application method for studying secure communication in the DNA field. [ABSTRACT FROM AUTHOR]

A novel method to extract the grating coupling coefficient of distributed feedback (DFB) lasers by comparing the theoretical and experimental values of the side mode spacing is demonstrated. Compared with the traditional method, the proposed method in this paper transforms the solution process of the lasing model with multiple unknown parameters into that with only the side mode spacing and coupling coefficient, which significantly reduces the computational workload. Furthermore, the bias current of the measured spectrum can be much higher than the threshold current, which makes the method less affected by noise. This paper theoretically analyzes the changing relationship between multiple parameters by calculating the lasing mode distribution, and the results show that the side mode spacing is only sensitive to the coupling coefficient. In addition, the grating coupling coefficients (57–61 cm−1) of the fabricated DFB laser diodes are experimentally extracted at 40-80 mA currents. The variation of the coupling coefficient with current is less than 2‰/mA, and the method exhibits pretty good stability. Meanwhile, the grating coupling coefficient extraction method for the complex grating types is also considered in this paper. [ABSTRACT FROM AUTHOR]

With the increase in number of VSC based HVDC systems, it is inevitable that there would be interconnections with weak ac grids. The paper presents the analytical basis for identifying coupling in the power loops which is dependent on grid inductance and operating point by utilizing the impedance based modeling technique. The formulation is used to define an inverse-based decoupling outer-loop controller for VSC-HVDC system. The concept is extended to HVDC grids and it is shown that the gains obtained using simple inverse may lead to instability. Robust controller tuning with pole-placement and minimization of $H_\infty$ norm is presented for HVDC grids, which form a restricted feedback system. The results show that the proposed method of decoupling results in effective decoupling of the power loops over a large range of grid inductance values as compared to that with traditional vector control. The system stability is also maintained over a large range of grid inductance values and PLL gains when a sudden variation of parameters is considered. The stability margins can be enhanced by pole-placement. The observations from the small-signal models are confirmed using detailed time-domain simulations. The proposal is expected to be useful in controller design for single VSC as well as HVDC grids, especially, during planing stage. [ABSTRACT FROM AUTHOR]

Variable leakage flux (VLF) interior permanent-magnet synchronous machines (IPMSMs), which use intentional magnet leakage flux paths cross-coupled with the q-axis flux paths to reduce losses over driving cycles, have been introduced recently, but self-sensing has not been discussed for these machines. This paper focuses on the saliency angular offset attributes that are the primary metric for the well-established injection-based self-sensing methods. This paper begins by evaluating the effect of the intentionally designed cross-coupling in the VLF-IPMSM with rotor surface bridges on the saliency angular offset. This paper then proposes alternate rotor designs with side-loop structure that cause relatively linear and well-behaved cross-coupling that improves the load-dependent saliency angular offset characteristics. The effect of VLF properties on power conversion and driving cycle loss reduction capability is evaluated for the proposed designs. This paper also applies the concept of VLF design to conventional flux-weakening interior permanent-magnet machine rotor design and presents the loss reduction capability of such designs. [ABSTRACT FROM AUTHOR]

A novel brushless self-excited air-core compensated pulsed alternator (BSACPA) is presented in this paper. It consists of two submachines in cascade, among which one serves as an exciter and the other works as a generator. The rotor windings of the two submachines are connected by a reverse phase sequence to realize reversal of the magnetic field. The stator windings are connected by a rectifier to realize the brushless self-excited structure. As an air-core compensated pulsed alternator (CPA) of new topology, it is necessary to derive its mathematical model and carry out a comparative design. Thus, this paper focuses on the detailed design and analysis of a BSACPA prototype, which includes dimensional design and equivalent circuit establishment. In addition, the critical speed is also acquired. Accordingly, the numbers of winding coil turns are designed to increase the discharge current and power based on the theoretical analysis. Finally, the analysis and design are verified by finite-element analysis (FEA). [ABSTRACT FROM AUTHOR]

This paper presents a new bandwidth tuning theory for Butterworth-response resonator filters. The presented theory shows that the bandwidth of odd-order Butterworth filters can be varied by adjusting only two interresonator coupling structures while maintaining a perfect impedance matching at the center frequency. In other words, this paper presents an analytic approach to reduce the number of tunable coupling structures when designing a bandwidth-tunable resonator filter. Theories for third- and fifth-order direct-coupled filters are discussed in detail, and it is shown that only two interresonator coupling structures are required to be tunable. In addition, for verifying the new bandwidth tuning method, a fifth-order cylindrical cavity filter has been designed, fabricated, and measured. The fabricated filter has an 11:1 bandwidth tuning range. [ABSTRACT FROM AUTHOR]

Spatially-coupled (SC) codes are a family of graph-based codes that have attracted significant attention, thanks to their capacity approaching performance and low decoding latency. An SC code is constructed by partitioning an underlying block code into a number of components and coupling their copies together. In this paper, we first introduce a general approach for the enumeration of detrimental combinatorial objects in the graph of finite-length SC codes. Our approach is general in the sense that it effectively works for SC codes with various partitioning schemes, column weights, and memories. Next, we present a two-stage framework for the construction of high performance binary SC codes optimized for the additive white Gaussian noise channels; we aim at minimizing the number of detrimental combinatorial objects in the error floor region. In the first stage, we deploy a novel partitioning scheme, called the optimal overlap partitioning, to produce the optimal partitioning corresponding to the smallest number of detrimental objects. In the second stage, we apply a new circulant power optimizer to further reduce the number of detrimental objects in the lifted graph. SC codes constructed by our new framework have up to two orders of magnitude error floor performance improvement and up to 0.6 dB SNR gain compared to prior state-of-the-art SC codes. [ABSTRACT FROM AUTHOR]

This paper presents a novel quarter-mode packaged bandpass filter with four transmission zeros (TZs) in substrate-integrated waveguide (SIW) technology. The filter has an insertion loss of 2.85 dB at 30 GHz and fractional bandwidth of 20%. The design methodology of the TZs was first demonstrated to increase the attenuations of the filter stopband. The quarter-mode SIW resonators were analyzed with high-mode suppression by properly setting their feed points. The packaged filter was consistent between the simulation and measurement results and offers the advantages of compact configuration and easy integration with other devices. Mode suppressions of up to 110 GHz were also provided. The proposed concept is attractive for designing miniaturized and high-performance-packaged filters for 3-D millimeter-wave transceiver systems. [ABSTRACT FROM AUTHOR]

This paper proposes an accurate impedance model for line commutated converter (LCC) in the stationary frame. The commutation overlap process caused by the transformer leakage inductance complicates the modeling for LCC. Traditional impedance models are derived in positive sequence and negative sequence frame based on the simplified commutation overlap process, which degrades the modeling accuracy and limits the description of frequency coupling. This paper systematically analyzes the effects of the commutation overlap process on the impedance model, and the impedance model with the accurate commutation overlap process is established in the dq-frame. For clearly revealing the frequency coupling phenomenon of the LCC, the complex space vector is employed to extend the impedance model in the dq-frame to the complex αβ-frame. A closed-loop model on PSCAD/EMTDC is used to verify the proposed impedance model in the time-domain and the frequency-domain. The consistency between the simulation results and theoretical analysis effectively verifies the accuracy of the proposed model. [ABSTRACT FROM AUTHOR]

To improve the torque accuracy for open-end winding permanent magnet synchronous motor (OEW-PMSM) with common dc bus, it is necessary to eliminate the zero-sequence torque (ZST) caused by zero-sequence current (ZSC) and the third back electromotive force. But the third flux linkage mismatch can enlarge ZSC which causes torque ripple. To deal with the above problem, firstly, a q-axis current injection method combined with deadbeat predictive current control (DPCC) is adopted to inject an extra current into the reference q-axis current. The extra torque generated by this injected current can compensate for ZST. Secondly, to ensure the accuracy of the q-axis injected current, a parameter identification method based on recursive least square (RLS) algorithm with forgetting factor is presented to identify the third flux linkage accurately. The identification value can reduce ZSC and torque ripple under different working conditions. And the accurate q-axis injected current can be obtained to counteract ZST and output accurate torque. Finally, three methods are comparatively analyzed in this paper, namely the traditional DPCC method, the DPCC method with q-axis current injection and the proposed DPCC method based on RLS with forgetting factor. The simulation and experimental results verify the effectiveness of the proposed DPCC method. [ABSTRACT FROM AUTHOR]

For the short-term high torque output, an improved model predictive direct torque control (MPDTC) method with field enhancing is proposed to increase torque. In order to avoid the possible loss of synchronism while increasing torque, the MPDTC method limits the load angle in the cost function. Under the constant load angle limitation, the improved method increases the torque output capability by increasing the magnetic field. This paper starts from the torque calculation, theoretically analyzes the torque-load angle characteristics, and illustrates the flux vector trajectory with the voltage limit circle and current limit circle. The proposed method maintains the dynamic and static performance of the traditional MPDTC method while ensuring the system stability. The experimental results show that the torque capacity of the proposed method has been improved, and it has stable extreme output torque. So, some applications, such as electric load simulators, can choose the motor with small capacity and small inertia, thereby weakening negative effects of the inertia torque. [ABSTRACT FROM AUTHOR]

Linkages between science and technology have been extensively studied using nonpatent literature citations or author-inventor matching. These methods suffer from limitations, such as the lack of citations to relevant documents or challenges with the disambiguation of author–inventor linkages. To mitigate these limitations, this paper uses Latent Dirichlet Allocation to create topic-based linkages between publications and patents based on the semantic content in the documents. The approach allows for the detection of topical overlap between patent and scientific publications, highlighting topical areas shared by research and application. Using a case study on “Taxol,” a cancer drug, with in total 26 475 documents retrieved from EuropePMC database the study illustrates the performance of the approach. The study offers qualitative and quantitative support that the approach is valuable in detecting patent and publication linkages. [ABSTRACT FROM AUTHOR]

A semi-high-speed magnetic levitation (maglev) train with a maximum speed of 200 km/h is being developed in Korea. It utilizes linear induction motors for propulsion and adopts electromagnetic suspension for levitation. For high-speed operation, guidance systems should be adopted to stabilize the train especially on curved tracks. For compatibility of the rail with previously developed urban maglev trains, the installation of the guidance electromagnet has to be restricted to be placed near the levitation electromagnet. Owing to the spatial closeness, mutual magnetic flux by the levitation and guidance electromagnets is produced at an overlapping portion of the rail. For stable control of the two systems, the coupling effects must be analyzed, because the levitation and guidance electromagnets are not operated independently. This paper aims to analyze the coupling effects by considering the magnetic field and a magnetic equivalent circuit. This paper suggests levitation and guidance systems for the semi-high-speed maglev train by considering each electromagnetic characteristic depending on the current direction. [ABSTRACT FROM AUTHOR]

Some electromagnetic pulses, such as the high-altitude electromagnetic pulse (HEMP), can couple with power lines in the range of thousands of kilometers. Conventional numerical methods cannot efficiently predict the voltage induced by the early-time (E1) HEMP on the power lines in a large area. This paper presents an efficient model based on an artificial neural network (ANN) which can predict the coupled voltage induced by the E1 HEMP on distribution power lines quickly. Based on Agrawal's model of the electromagnetic field coupling with transmission lines, the important parameters which affect the coupled voltages of distribution power lines are analyzed firstly. The Baum-Liu-Tesche equation and inverse Fourier transform is applied to compute the voltage magnitude when the elevation angle, azimuth angle, and the polarization angle of the E1 HEMP change and more than twenty thousand numerical results are obtained. Then an ANN is developed and trained by the numerical results. Once the ANN is trained, the prediction time is on the order of milliseconds. The results show that the proposed model based on the ANN can provide accurate prediction results for the E1 HEMP coupling with power lines at different observation points. [ABSTRACT FROM AUTHOR]

In actual line-commutated converter based high- voltage direct-current (LCC-HVDC) projects, multiple HVDC transmission lines are usually installed on the same tower to save transmission corridors and reduce construction costs. However, electromagnetic coupling effect between adjacent lines can cause commutation failure (CF) in the non-fault poles when a line or pole fails. Hence, this paper deeply investigates the mechanism and the prevention strategy of CFs caused by line coupling effect in single- and double-circuit HVDC systems. The influencing factors of line coupling effect and the coupling characteristics under fault conditions are analyzed first based on the modeling of parallel transmission lines and the traveling wave theory. Then the mechanism of CF caused by line coupling effect is investigated with the consideration of different fault conditions, different line structures, and different system operation modes. Based on the above analyses, prevention strategies for CFs of non-fault poles in single- and double-circuit systems are proposed. Finally, the simulation results verify the correctness of the theoretical analyses and the effectiveness of the proposed control strategies. [ABSTRACT FROM AUTHOR]

This paper proposes a temporal decomposition strategy to reduce the computation time of security-constrained unit commitment (SCUC). The novelty of this paper is twofold. The scheduling horizon is decomposed into multiple subhorizons. The concept of coupling intervals is introduced, and a set of auxiliary counting variables and logical expressions along with their equivalent linear models are formulated to handle intertemporal ramp constraints and minimum on/off times between consecutive subhorizons. An accelerated analytical target cascading (A-ATC) algorithm is developed to coordinate SCUC subproblems and find the optimal solution for the whole operation horizon in a distributed manner. An initialization strategy is presented to enhance the convergence performance of A-ATC. The proposed algorithm is tested on four test systems. [ABSTRACT FROM AUTHOR]

Modularization design has been widely used to reduce the detent force of permanent magnet linear synchronous motor (PMLSM). For modular PMLSM, ideally, unit motors are independent of each other and the detent force of the whole motor is the sum of that for unit motors; thus, the whole motor's detent force can be suppressed by adjusting the phase difference among the unit motors’ detent forces. But actually, there is coupling effect between adjacent unit motors, which has adverse effect on the detent force suppression. The coupling effect changes the magnetic field distribution, which is often neglected in current research. Hence, this paper carries out the research on magnetic field analysis and flux barrier design for modular PMLSM considering the coupling effect: the influence of the coupling effect on the air gap magnetic field is clarified through magnetic field analysis; the coupling force is isolated by finite element analysis, and then the effects of key parameters are discussed; the whole motor's detent force model considering the coupling effect is established, and an optimal design method of adjusting the flux barrier length is presented to suppress the detent force. Finally, a prototype is made to test the detent force characteristics with different flux barrier lengths, which verifies the research theory in this paper. The research results in this paper can provide guidance and reference for the design of modular PMLSMs. [ABSTRACT FROM AUTHOR]

Transformations between abc, stationary dq0 ($\alpha \beta 0$) and rotating dq0 reference-frames are used extensively in the analysis and control of three-phase technologies such as machines and inverters. Previous work on deriving the matrices describing these transformations follows one of two approaches. The first approach derives Clarke's matrix by modifying symmetrical components. Park's matrix can be subsequently found from a rotation matrix. The second approach derives Park's matrix using trigonometric projection by interpreting the transformation as a rotation in the plane of the cross-section of a machine. Then, Clarke's matrix can be found trivially using a reference angle of zero in Park's matrix. This paper presents a third approach to deriving the Clarke and Park transformation matrices: a geometric interpretation. The approach exploits properties of the linear transformation using the Cartesian representation. We introduce the locus diagram of a three-phase quantity and show how these diagrams have applications in power quality. We show that, unlike a phasor diagram, a single locus diagram can fully represent a three-phase system with harmonics. [ABSTRACT FROM AUTHOR]

This paper describes a method to provide low-voltage four-wire three-phase power converters with the capability of unbalance estimation as an ancillary service to the main role that they play in the distribution system (distributed generator, energy storage system, drive, etc.). Typically, dedicated grid/load current sensors are needed to effectively comply with unbalance compensation tasks, increasing system cost and reducing reliability. This is due to the difficulties that arise in the extraction of the zero- and negative-voltage components from the voltages at the point of common coupling, such as the inadequate resolution of full-scaled voltage sensors and limited spectral separation. In this paper, the proposed method does not rely on additional sensors to those typically used in voltage-source converters, and in any case, those sensors are limited to the point of connection of the power converter. Impedance estimation only using converter-side current sensors is implemented by adding a high-frequency voltage excitation over the fundamental command. A new model approach is proposed for the real-time extraction of system impedance using a complex-valued compact form. Considering the voltage source at that frequency to be unique in the grid, it will be proved that the impedance and, thus, the resulting negative-sequence current, which is used for unbalance compensation, can be estimated. For the zero sequence, a special arrangement of the converter voltage sensors together with a repetitive controller is used. [ABSTRACT FROM AUTHOR]

In this paper, a simplified model of a 2 × 25 kV bi-level traction power system for feeding high-speed trains is presented. A modified nodal analysis (MNA) based algorithm for solving the system with and adaptive damping factor is also explained. The main novelties of this paper are the inclusion of train protections (over-current and over-voltage) in the model and the development of the MNA solving procedure that increases the stability and robustness of the iterative solving process. Another important feature of the model is that it can be easily adapted to a single voltage feeding systems by deactivation of specific parameters. The accuracy and performance of the proposed simulator is compared and verified relative to the derivative based solvers. [ABSTRACT FROM AUTHOR]

Confocal gyrotron traveling-wave tube (gyro-TWT) is capable of operating in higher order modes, so it is attractive in high-frequency (> 100 GHz) band. However, the reported experimental and simulation results of confocal gyro-TWT usually operated at fundamental harmonic, so high external magnetic field was essential. In this paper, a second harmonic 220-GHz confocal gyro-TWT was designed through linear and nonlinear theory and particle-in-cell (PIC) simulation. The key problem of suppressing the backward-wave oscillations (BWOs) of both fundamental and second harmonics was solved by limiting the cavity length of the first section less than the critical BWOs length. In PIC simulations, the gyro-TWT operates at HE07 mode with an output power of 4.55 kW, the efficiency of 2.2% gain of 21.8 and the −3 dB bandwidth of 6 GHz. The calculated results from the nonlinear theory are in good agreement with the results from PIC simulation. [ABSTRACT FROM AUTHOR]

Co-simulation of heterogeneous systems allows for in-depth analysis of various aspects of power systems’ operation while staying within the environments of the simulation tools that are best fit to represent their respective domains. Equipped with a proprietary co-simulation platform, the paper focuses on the issue of power-conjugate coupling between parts of power grids modeled in transient stability and electromagnetic transient simulation tools. The problems of co-simulation stability and precision in presence of delays are tackled by means of designing a proper coupling interface. It is shown that two established interface methods – the V-I method and the Transmission Line Interface – are special cases of a generalized interface framework proposed in the paper. Moreover, a new interface algorithm is described by parametrizing the generalized framework. Analytical tools are also formulated to aid in the analysis of interface stability and precision via the concepts of passivity and transparency. Simulation results of benchmark systems of various complexity demonstrate the application of the developed power coupling interface. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) charging at low temperatures will easily accelerate the aging of LIBs and reduce the useful life. This paper applies advanced multi-factors coupling aging model and bi-objective particle swarm optimization (PSO) algorithm to derive suitable charging patterns for LIBs at low temperatures. Based on the results of orthogonal experiments, which consider the effects of charging rate, charging temperature and charging cut-off voltage on battery aging, the low-temperature capacity degradation model was established. Furthermore, two important yet competing charging objectives, including battery health and charging time, are taken into account simultaneously. These two conflicting charging objectives are traded off by solving a bi-objective optimization problem based on battery electrothermal and aging behavior. Combined with PSO algorithm, the optimal low-temperature charging strategy is obtained. As a result, the three-stage constant current and constant voltage (CC-CV) charging strategy is optimized to balance various combinations of charging objectives. Different tradeoffs are compared and analyzed based on the Pareto frontiers. The verification results show that the optimized three-stage CC-CV charging strategy can effectively offer feasible health-conscious charging with desirable tradeoffs among charging speed and battery health under low-temperature charging conditions. [ABSTRACT FROM AUTHOR]

Based on the evolutionary game theory, this paper explores the evolutionary stable strategy (ESS) of university–industry collaborative innovation. By utilizing MATLAB software, the analysis of the influence of agent coupling degree, group size, and government policies on the stable evolution of university–industry collaborative innovation is taken into account, while simulating. Our findings indicate that, first, agent coupling degree is positively and nonlinearly related to the stable evolution of university–industry collaborative innovation; second, when an enterprise's size is equal to university's, group size is more significant to the stable evolution of university–industry collaborative innovation than agent coupling degree; third, when a group size of an enterprise and university is different, the combinations of agent coupling degree and group size have various effects on the stable evolution of enterprise group and university group; and fourth, government policies have a significantly positive impact on the stable evolution of university–industry collaborative innovation, and incentive measures are more effective than punitive ones. Research conclusions have developed the relationship among university–industry collaborative innovation agents, expanded the boundary of the stability study of collaborative innovation, and provided new ideas for improving the effectiveness of government innovation policies. [ABSTRACT FROM AUTHOR]