Design of Concurrent Tri-Band High-Efficiency Power Amplifier Based on Wireless Applications

To meet the existing requirements of multiband communication and improve the efficiency and performance of communication RF modules, a concurrent tri-band high-efficiency power amplifier operating in three frequency bands is proposed. The input and output impedance values of concurrent power amplifier is analyzed, and the input and output-matching circuit and bias circuit are designed. Through the impedance compensation principle, the impedance matching of three frequency bands is realized, and the amplifier can maintain high power and high efficiency at three arbitrary wide interval frequencies. To this end, a simultaneous tri-band power amplifier is designed and tested by using transistor CGH40010F. The experimental results show that the peak power of the designed simultaneous tri-band high-efficiency power amplifier is more than 10 W, the power-added efficiency reaches 55~69%, and the amplification gain is about 10 dB at three frequency bands of 2.2, 2.6, and 3.5 GHz. The design of concurrent tri-band high-efficiency power amplifier is flexible, the calculation of microstrip line parameters is simple, and it can work in three frequency bands simultaneously. It provides an effective structure scheme for designing concurrent power amplifiers in transmitting systems

A Broadband Power Amplifier Based on a Novel Filter Matching Network

This paper presents a new realization method of a broadband power amplifier based on a novel filter matching network. The novel matching network based on band-pass filter has an excellent frequency-selection function, which can ensure the novel matching network has excellent characteristics in the aim band and generates the out-of-band harmonic suppression. Finally, we manufactured the power amplifier and measured it. The saturated output power is greater than 40 dBm in the range of 1 to 3 GHz, limited to ±1.5 dB of the gain flatness, and the rejection of harmonic is stronger than −20 dBc

Design of double-notch UWB filter with upper stopband characteristics based on ACPW-DGS.

In this manuscript, a compact (size only 9.8mm*9.8mm) Ultra Wide Band (UWB) bandpass filter with a new structure is proposed, which can be used in the UWB wireless communication band authorized by the FCC. The top plane is composed of a pair of back-to-back microstrip lines, and the ground plane structure is based on an asymmetric coplanar waveguide-defect ground structure (ACPW-DGS). UWB is formed by the vertical electromagnetic coupling of the top plane and the ground plane. On this basis, split ring resonator (SRR) and C type resonator (CTR) are utilized to place double notch bands. A novel third order nested C-type resonator (TONCTR) is obtained by performing CTR, which can further optimize the upper stopband while ensuring double notch bands. The filter can be used for filtering within the UWB system, and it can also avoid the amateur radio band (9.2 -10.3GHz) and the X-band satellite link band (9.6-12.3GHz) on UWB communication systems. Finally, the measured results from the fabricated prototype are basically consistent with the simulation results

Research on Multi-View 3D Reconstruction Technology Based on SFM

Multi-view 3D reconstruction technology is used to restore a 3D model of practical value or required objects from a group of images. This paper designs and implements a set of multi-view 3D reconstruction technology, adopts the fusion method of SIFT and SURF feature-point extraction results, increases the number of feature points, adds proportional constraints to improve the robustness of feature-point matching, and uses RANSAC to eliminate false matching. In the sparse reconstruction stage, the traditional incremental SFM algorithm takes a long time, but the accuracy is high; the traditional global SFM algorithm is fast, but its accuracy is low; aiming at the disadvantages of traditional SFM algorithm, this paper proposes a hybrid SFM algorithm, which avoids the problem of the long time consumption of incremental SFM and the problem of the low precision and poor robustness of global SFM; finally, the MVS algorithm of depth-map fusion is used to complete the dense reconstruction of objects, and the related algorithms are used to complete the surface reconstruction, which makes the reconstruction model more realistic

Seismic Performance Target and Fragility of Masonry Infilled RC Frames under In-Plane Loading

Masonry infilled RC frames are one of the most common structural forms, the damage of which, in earthquake events, usually cause serious losses. The determination of the seismic performance target is the key foundation of performance-based seismic evaluation and design for masonry infilled RC frames. In this paper, an extensive database of experimental tests on infilled RC frames loaded in an in-plane direction is collated. According to the crack propagation and elastic-plastic characteristics of infilled RC frames, the damage process is divided into four stages, and then the criteria of the damage states (DS) are proposed. In addition, the seismic performance targets expressed as inter-story drift ratio (IDR) for the four stages are suggested, which would support the performance-based in-plane seismic analysis of infilled RC frames. Finally, the proposed in-plane seismic performance target is utilized to analyze the fragility of two masonry infilled RC frame structures

Trichosanthes pericarpium Aqueous Extract Enhances the Mobilization of Endothelial Progenitor Cells and Up-regulates the Expression of VEGF, eNOS, NO, and MMP-9 in Acute Myocardial Ischemic Rats

Trichosanthes pericarpium (TP) had been widely used to cure patients of cardiovascular disease for 2,000 years in China. This study aims to extend our previous work to explore the mechanism underlying the protective effect of TP on acute myocardial ischemia (AMI). We hypothesized that TP may display its protective effect on AMI by promoting the mobilization of endothelial progenitor cells (EPC) via up-regulating the expression level of vascular endothelial growth factor (VEGF), endothelial nitric oxide syntheses (eNOS), nitric oxide (NO), and matrix metalloproteinase 9 (MMP-9) in AMI rats. To confirm this hypothesis, we treated AMI model rats with intragastrical administration of TP aqueous extract (TPAE), and examined both changes in the number of CEPC, and the expression levels of VEGF, eNOS, NO, and MMP-9 in myocardial tissue and their plasma content in these rats. Rats in each group were randomly divided into seven subgroups. From day 1 to 7 following AMI modeling, rats in these subgroups was sequentially phlebotomized from their celiac artery after being anesthetized by chloral hydrate. We found that, compared with the AMI model rats, in rats treated by TPAE, the CEPC counts, the expression of VEGF, eNOS, NO, and MMP-9 in myocardial tissue and their plasma content all increased more rapidly 7 days after AMI and remained at higher level (P < 0.05 or P < 0.01). Our results showed that, in AMI rats, the TPAE could significantly promote the mobilization of EPC and up-regulate the expression level of VEGF, eNOS, NO, and MMP-9 in myocardium and their plasma content. Therefore, our results suggest that TAPE may regulate EPC mobilization through up-regulating the expression level of VEGF, eNOS, NO and MMP-9 in the myocardium of AMI rats

Co₂P@N,P-codoped carbon nanofiber as a free-standing air electrode for Zn-air batteries : synergy effects of CoNₓ satellite shells

Here, a free-standing electrode composed of cobalt phosphides (Co₂P) supported by cobalt nitride moieties (CoNₓ) and an N,P-codoped porous carbon nanofiber (CNF) in one-step electrospinning of environmentally friendly benign phosphorous precursors is reported. Physiochemical characterization revealed the symbiotic relationship between a Co₂P crystal and surrounding nanometer-sized CoNₓ moieties embedded in an N,P-codoped porous carbon matrix. Co₂P@CNF shows high oxygen reduction reaction and oxygen evolution reaction performance owing to the synergistic effect of Co₂P nanocrystals and the neighboring CoNₓ moieties, which have the optimum binding strength of reactants and facilitate the mass transfer. The free-standing Co₂P@CNF air-cathode-based Zn-air batteries deliver a power density of 121 mW cm⁻² at a voltage of 0.76 V. The overall overpotential of Co₂P@CNF-based Zn-air batteries can be significantly reduced, with low discharge-charge voltage gap (0.81 V at 10 mA cm⁻²) and high cycling stability, which outperform the benchmark Pt/C-based Zn-air batteries. The one-step electrospinning method can serve as a universal platform to develop other high-performance transition-metal phosphide catalysts benefitting from the synergy effect of transition nitride satellite shells. The free-standing and flexible properties of Co₂P@CNF make it a potential candidate for wearable electronic devices.This work was supported by the National Natural Science Foundation of China (Grant No. 51502135) and the Natural Science Foundation of Fujian Province of China (Grant No. 2017J01005)

Space experimental investigation of drop evaporation process onboard scientific satellite SJ10: preliminary results and theoretical analyses

International audienc

Damping and Mechanical Properties of Epoxy/316L Metallic Lattice Composites

The lattice structure was prepared by selective laser melting of 316L metal powder, and the epoxy was naturally infiltrated into the pores of the 316L metallic lattice structure. The epoxy/316L metallic lattice composites with integrated structure and function were prepared. Scanning electron microscopy was used to observe the microstructure of the epoxy/316L metallic lattice composites. The damping performance of the epoxy/316L metallic lattice composites were studied by modal measurement method. At the same time, the engineering stress–strain curve was obtained by a quasi-static compression experiment on a universal testing machine. The results show that the interface of epoxy and 316L metallic lattice is well bonded, and there are a few bubbles in the epoxy. The epoxy/316L metallic lattice composites have high damping characteristics with damping ratio over 10%. The energy absorption of epoxy/316L metallic lattice composites is as high as 68.32 MJ/m3, showing high energy absorption characteristics