《Journal of the European Ceramic Society》2022,42(13):5771-5777

A novel Zn_1-xCo_xMoO₄ (ZCMO) (x = 0.03) ceramic with low-dielectric constant, low-loss, and low-sintering temperature for 5G electromagnetic beam splitting is developed by solid-state reaction method. This ceramic exhibits excellent microwave dielectric properties with ε_r = 8.0, Q × f = 57682 GHz, τ_f = ? 54.9 ppm/°C at a sintering temperature of 825 °C. An array antenna for electromagnetic beam splitting at 5.4 GHz is designed by using this ceramic for the first time. The highest efficiency and the best electromagnetic beam splitting effect can be jointly controlled by the dielectric constant and dielectric loss of the ceramic. The normalized reflection amplitude of each array unit cell is above 98 %, and the reflection phase covers 360°. The function of electromagnetic beam splitting is verified by the far-field pattern of the electric field. This work helps to promote the development of LTCC and broaden the application scope of microwave dielectric ceramics.  相似文献   

    

《Organic Electronics》2021

Since the emergence of organic-inorganic hybrid perovskites, the development of perovskite light-emitting diodes (PeLEDs) with green/red emission have made great progress, and the corresponding external quantum efficiency (EQE) has exceeded 20%. However, the research progress of blue-emitting PeLED still has certain challenges. In this article, a multi-cation per-bromine perovskite film is prepared by introducing polymer molecules poly(9-vinylcarbazole) (PVK) in an anti-solvent (chloroform). When the concentration of PVK is optimized to 0.1 mg/mL, a smooth, dense, high-quality film with photoluminescence quantum efficiency (PLQY) up to 20.70% is obtained. The introduction of PVK can assist the formation of perovskite films for interface modification via surface defect passivation. The optimized blue PeLED has a maximum brightness of 3136 cd/m² and a maximum EQE of 3.49% at 488 nm. More importantly, the optimized blue PeLED has excellent color stability under high applied voltage up to 12 V or continuous operation.  相似文献   

    

《Organic Electronics》2021

The reported NiO_x interfacial layers in blue perovskite light-emitting diodes (PeLEDs) usually require high-temperature annealing and complex interface modification. Herein, we report a kind of uniform NiO_x anode interfacial layer induced by H₂O treatment, which effectively enhances the brightness and light-emitting efficiency of blue PeLEDs simultaneously. Compared to the as-prepared NiO_x anode interfacial layer, H₂O treatment renders uniform and pinhole-free NiO_x morphology. The solution-processed perovskite blue emissive layer prepared atop the H₂O-treated NiO_x interfacial layer demonstrates enhanced photoluminescent property and superior morphology with low trap density. The blue PeLEDs employing H₂O-treated NiO_x as anode interfacial layer show a maximum luminance of 9052 cd/m² and a maximum external quantum efficiency (EQE) of 1.80%, whereas the control device based on the as-prepared NiO_x anode interfacial layer merely exhibits a maximum luminance of 3850 cd/m² and an EQE of 0.88%, leading to about 135% and 104% increase in brightness and efficiency, respectively. The PeLEDs emit pure blue light with emission peak located at 482 nm and demonstrate superior spectral stability under different driving voltages and operating time.  相似文献   

    

《Microprocessors and Microsystems》2020

High efficient current limiting controller is mandatory to obtain ripple-free torque and required speed level in the output of the Permanent Magnet Synchronous Motor (PMSM) drives. In this paper, substantial analysis is taken to control the output torque ripple, to minimize the acoustic noise and also to get the required speed by simulating PMSM with three different investigators such as SVPWM, Model Predictive Control (MPC) and Dead-Beat (DB) Predictive Controller. The designed controllers are tested through the numerical simulations in the MATLAB Simulink Platform and also experimental validation is taken in the laboratory. These predictive investigators are implemented to get good transient response, less torque ripple; reduced harmonics in phase currents and also with delay compensation. The comparison between the simulation and experimental results are presented at the end. The DBP control is suitable for the high performance applications and it is easy to implement in the PMSM drives.  相似文献   

    

《Journal of Visual Communication and Image Representation》2020

Convolutional neural networks (CNNs) with large model size and computing operations are difficult to be deployed on embedded systems, such as smartphones or AI cameras. In this paper, we propose a novel structured pruning method, termed the structured feature sparsity training (SFST), to speed up the inference process and reduce the memory usage of CNNs. Unlike other existing pruning methods, which require multiple iterations of pruning and retraining to ensure stable performance, SFST only needs to fine-tune the pretrained model with additional regularization on the less important features and then prune them, no multiple pruning and retraining needed. SFST can be deployed to a variety of modern CNN architectures including VGGNet, ResNet and MobileNetv2. Experimental results on CIFAR, SVHN, ImageNet and MSTAR benchmark dataset demonstrate the effectiveness of our scheme, which achieves superior performance over the state-of-the-art methods.  相似文献   

    

《Journal of Process Control》2020

In this paper, we study the problem of integrated well pad development scheduling with nonlinear model predictive control based steam injection in steam-assisted gravity drainage (SAGD). The scheduling problem has been modeled as a mixed-integer program to find optimal development sequence and timing of multiple well-pads. Model predictive control problems are solved to find optimal steam injection profile such that the reservoir is under control. The integrated problem is solved using open-loop and closed-loop methods: (1) scheduling problem is only solved at the beginning of project operation, (2) Scheduling problem is solved every year with shrinking horizon implementation, and (3) shrinking horizon implementation of scheduling with reservoir model update based on feedback from control level. Simulation results demonstrate the benefits of closed-loop integrated scheduling and control: the NPV increase is 19%.  相似文献   

    

《Journal of Process Control》2020

This study deals with the tracking problem for a class of nonstrict-feedback switched nonlinear systems (SNSs) with unknown time-delay and unknown functions under arbitrary switching. To achieve this goal, an adaptive neural network-based dynamic surface control (DSC) based on backstepping approach is proposed. A neural network (NN) approximator based on radial basis functions (RBFs) is utilized to approximate unknown functions. Considering properties of Gaussian basis function in RBFNNs, an adaptive neural network DSC for nonstrict-feedback structure has been developed. A Lyapunov-krasovskii functional is applied to compensate the effect of unknown delay terms. Furthermore, a prescribed performance bound (PPB) control strategy is utilized to retain the tracking error within a predefined bound. Finally, a practical example is provided to prove the effectiveness of the proposed method.  相似文献   

    

《AEUE-International Journal of Electronics and Communications》2018

A dual symmetrical coplanar waveguide (CPW)-fed small size wideband printed square slot antenna (SSA) with dual linearly and circularly polarized radiation capability is presented. The antenna is composed using a square slot, two symmetrical orthogonal CPW feed lines connected to horizontal and vertical arm of L-shaped radiator, an embedded parasitic inverted-L strip at the lower left corner of the square ground slot and engraving slots in the ground plane. Circular polarization (CP) is achieved due to two orthogonal CPW feed lines and a common L-shaped radiator. Isolation between ports is improved by engraving slots at the lower left corner of ground plane and embedded parasitic inverted-L strip. The sense of dual-polarization can be changed in pass-band by changing the port excitation. Measured antenna reveals that an 84.4% (4.6 GHz, 3.15–7.75 GHz) −10 dB impedance bandwidth (IBW) and about 33% (2.03 GHz, 5.12–7.15 GHz) 3-dB axial ratio bandwidth (ARBW). Isolation between ports <−16 dB is achieved over usable CP band.  相似文献   

    

《AEUE-International Journal of Electronics and Communications》2018

In this paper, a miniaturized absorber realized on interleaved structure across X-band is reported. The presented absorber has been designed based on the concept of complementary interleaved Brigid’s cross. Results show that the structure rejects 9.88 GHz with absorption rate of almost 99%. Moreover, the absorber is polarization independent, as it maintains stability against TE- and TM-polarizations. The results from waveguide simulator and space wave measurements provide an efficient absorber at sub-wavelength spacing.  相似文献   

    

《AEUE-International Journal of Electronics and Communications》2018

This article inspects partially segmented circular monopole with elliptical slot for super wideband applications. Two significant characteristics of proposed antenna design are: (i) partially segmented circular monopole, notch loaded elliptical ground plane along with tapered microstrip line provides super wide bandwidth; (ii) elliptical slot in between the partially segmented circular monopole reduces the lower operating frequency (1.07 GHz–0.96 GHz), which in turn enhance the bandwidth dimension ratio (BDR). For verifying the simulated outcomes, antenna prototype is practically constructed and measured. The proposed antenna design attains frequency range from 0.96 GHz to 10.9 GHz (VSWR < 2) with bandwidth ratio of 11.35:1 and percentage bandwidth of 167.22%. Bandwidth dimension ratio of proposed radiator is 6975.22. Frequency as well as time domain analysis of proposed radiator approves its applicability for super wideband wireless applications.  相似文献