http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Yu Zeqi (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
-
Yu, Zeqi,Bai, Ge,Zhang, Ke,Xu, Jin The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.5
This paper presents a novel spread spectrum (SS) method with a pseudo-natural sampling technique for filterless digital class-D audio amplifiers. This method is proposed to reduce the electromagnetic interference (EMI) emissions of amplifiers by lowering the output out-of-band spectral amplitudes around the pulse width modulator carrier frequency and its multiples. The main idea of this method is that the sampling frequency of the modulating signal and the carrier frequency are varied synchronously and randomly among three different values. Since the carrier frequency is variable, the polynomial interpolation Newton-Raphson (PI-NR) algorithm is modified to correct the harmonic distortion caused by uniform-sampling pulse width modulation (UPWM). Based on a field programmable gate array (FPGA), an experimental system is established to analyze the performances of the proposed method and other six reported SS methods. Experimental results show that the proposed method features the lowest total harmonic distortion (THD) of 0.009% with a 6.6 kHz, 0 dBFS (full scale) input, a relatively high signal-to-noise ratio (SNR) of 52.68 dB and a relatively high output out-of-band peak spectral amplitude reduction of 17.75 dB.
-
Joint Space-time Coding and Power Domain Non-orthogonal Multiple Access for Future Wireless System
( Jin Xu ),( Hanqing Ding ),( Zeqi Yu ),( Zhe Zhang ),( Weihua Liu ),( Xueyan Chen ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.1
According to information theory, non-orthogonal transmission can achieve the multiple-user channel capacity with an onion-peeling like successive interference cancellation (SIC) based detection followed by a capacity approaching channel code. However, in multiple antenna system, due to the unideal characteristic of the SIC detector, the residual interference propagated to the next detection stage will significantly degrade the detection performance of spatial data layers. To overcome this problem, we proposed a modified power-domain non-orthogonal multiple access (P-NOMA) scheme joint designed with space-time coding for multiple input multiple output (MIMO) NOMA system. First, with proper power allocation for each user, inter-user signals can be separated from each other for NOMA detection. Second, a well-designed quasi-orthogonal space-time block code (QO-STBC) was employed to facilitate the SIC-based MIMO detection of spatial data layers within each user. Last, we proposed an optimization algorithm to assign channel coding rates to balance the bit error rate (BER) performance of those spatial data layers for each user. Link-level performance simulation results demonstrate that the proposed time-space-power domain joint transmission scheme performs better than the traditional P-NOMA scheme. Furthermore, the proposed algorithm is of low complexity and easy to implement.
-
Reusable, magnetic laser-induced graphene for efficient removal of organic pollutants from water
Jiang Ye,Wan Sijie,Zhao Weiwei,Yu Wenjie,Wang Shuaipeng,Yu Zeqi,Yang Qiu,Zhou Weihua,Liu Xiaoqing 한국탄소학회 2022 Carbon Letters Vol.32 No.4
The hybridization of graphene with magnetic nanoparticles has endowed graphene with increasing interest as the adsorbent for wastewater treatment. However, its fabrication often involves a multi-stepped chemical synthesis process. In this work, we demonstrate a facile, one-step, and solvent-free approach to fabricate Fe3O4 nanoparticle-anchored Laser-Induced Graphene (Fe3O4@LIG) as an efficient adsorbent by direct laser irradiation on a ferric acetylacetonate containing polybenzoxazine film. Raman and X-ray diffraction analysis confirm the graphene component in the adsorbent, and the morphology characterizations show that Fe3O4 nanoparticles are distributed uniformly on LIG with hierarchical meso- and macro-porous structures. Adsorption experiments indicate that Fe3O4@LIG can adsorb methylene blue (MB) from aqueous solutions in a fast and effective manner, with a maximum adsorption capacity up to 350.9 mg/g. The adsorption kinetics and isotherms are also investigated, which are well-described by the pseudo-second-order model and Langmuir model, respectively. Additionally, Fe3O4@LIG is also demonstrated with the efficient removal of a variety of organic solvents from water. The favorable adsorption behavior of Fe3O4@LIG is attributed to its unique porous structure and the molecular interactions with adsorbates. On the other hand, Fe3O4@LIG has high magnetic property, and therefore, it could be easily recovered from water and well regenerated for repeated use. With the efficient adsorption of organic pollutants, magnetic separability, and good recyclability, it is believed that the easy-fabricated Fe3O4@LIG has great potential applications in wastewater treatment.
KISS연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
