Degrees of Freedom of Two-Cluster MIMO Multiway Relay Interference Channels Using Blind Interference Neutralization

( Bowei Zhang ),( Wenjiang Feng ),( Tingting Dong ),( Yina Deng ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.1

In this paper, we investigate the degrees of freedom (DoF) of a two-cluster multiple-input multiple-output (MIMO) multiway relay interference channel (mRIC), where there are two relays and two users per cluster. In this channel, users within the same cluster exchange messages among themselves with the help of two relays. We first obtain the DoF upper bound of the considered MIMO mRIC based on cut-set bound. Then, we propose a novel transmission strategy, blind interference neutralization (BIN), to approach the DoF upper bound. This new method utilizes the overheard information at two relays and focuses on the beamforming matrix designs at two relays so that the channel state information (CSI) at users is not required. Through theoretical analysis and numerical simulations, we show that the DoF upper bound can be obtained by using the BIN scheme. From simulation results, we show that the proposed BIN scheme can provide significant performance gain over the conventional time division multiple access (TDMA) scheme in terms of DoF. In addition, we show that the BIN scheme is a superior approach to the existing signal space alignment (SSA) schemes for the considered mRIC.

明淸之際書籍環流與朝鮮女性詩文

張伯偉(Zhang Bowei) 고려대학교 한자한문연구소 2015 동아한학연구 Vol.- No.10

`연행록(燕行錄)` 및 관련 문헌의 `진실성(眞實性)` 문제 초탐(初探)

장백위 ( Zhang Bowei ) 성균관대학교 대동문화연구원 2017 大東文化硏究 Vol.97 No.-

`연행록` 및 관련 문헌의 사료적 가치는 의심할 여지없이 방대하면서도 귀중한 존재 의의를 지닌다. 연행 문헌에 관한 정리와 연구는 금세기 이래 동아시아 지역에서 주요 관심사가 되어 왔다. 그러나 우리는 이 문헌이 귀중한 점을 중시함과 동시에, 이런 종류의 문헌이 지닌 모종의 특징을 파악할 필요성과 기록 내용의 `진실성`에 대한 충분한 경각심이 요구됨에도 불구하고, 그것의 결핍으로 인해 오류 생산을 초래하고 있는 실정이다. 본고는 연행 문헌의 `失實`을 전후의 표절, 관찰 태도, `문화전쟁`의 장으로 나누고 각각의 상황에서 야기되는 실례를 중심으로 논의를 전개 하였다. 연행 문헌이 지닌 특징들에 대한 충분한 인지가 선행되어야 비로소 그 의미를 오류 없이 해독할 수 있을 것이다. In term of its value as historical records, "Travel Account to Beijing" and relevant documents are a huge and precious database for East Asian studies. From the beginning of the 21st century, the editing and research of "Travel Account to Beijing" more and more become a scholarly hotspot in East Asian community. Although scholars pay much attention to its important historical values, they seem to have grasped characteristics of such kind of records correctly, so are lack of vigilance on the "authenticity" of these data, which leads to some errors. This paper argues that the "inaccuracies" of "Travel Account to Beijing" were caused by plagiarism of later envoys to former records, reading attitude, and the context of "literary contest" between Korean envoys and Chinese official-scholars. Contemporary scholars should be aware of the characteristics of "Travel Account to Beijing" fully, then they could grasp the meanings the these data correctly.

Effect of Co Content on the Microstructure and Corrosion Behavior of Al0.3CoxCrFeNi High Entropy Alloys

Zequn Zhang,Qijuan Dong,Zhibin Chen,Junsheng Wu,Jiuyang Xia,Kang Huang,Pengcheng Zuo,Wei Xue,Bowei Zhang 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.2

The influence of Co content on the microstructure and corrosion behavior of Al0.3CoxCrFeNi (x = 0.25, 0.5 and 1.0) highentropy alloys were investigated. The results indicated that the increased content of Co improve the corrosion resistanceof alloy, which can be attributed to the distinction of phase composition in alloys caused by different Co content. TheAl0.3CoxCrFeNi alloy shows a double-phase (FCC + BCC) structure for x = 0.25 and 0.5, and BCC phase consists of (Al,Ni)-rich B2 phase and (Cr, Fe, Co)-rich A2 phase. The increase of Co content induces the transformations of crystalstructuresfrom BCC to FCC, resulting in the decrease of BCC phase proportion. The Al0.3CoCrFeNi alloy exhibits thesingle FCC structure, and all elements tend to be homogeneously distributed. The difference in the potential of FCC andBCC phases indicates the BCC phase acts as anode resulting to localized corrosion, while B2 phase preferentially dissolvescompared to the A2 phase due to the lower potential. Therefore, the existence of selective corrosion is found in thealloys with double-phase, by contrast, the alloy with single FCC phase shows random pitting corrosion.

Water film covering characteristic on horizontal fuel rod under impinging cooling condition

Zhang Penghui,Wang Bowei,Chen Ronghua,Su G.H.,Tian Wenxi,Qiu Suizheng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11

Jet impinging device is designed for decay heat removal on horizontal fuel rods in a low temperature heating reactor. An experimental system with a fuel rod simulator is established and experiments are performed to evaluate water film covering capacity, within 0.0287e0.0444 kg/ms mass flow rate, 0 e164.1 kW/m2 heating flux and 13.8e91.4C feeding water temperature. An effective method to obtain the film coverage rate by infrared equipment is proposed. Water film flowing patterns are recoded and the film coverage rates at different circumference angles are measured. It is found the film coverage rate decreases with heating flux during single-phase convection, while increases after onset of nucleate boiling. Besides, film coverage rate is found affected by Marangoni effect and film accelerating effect, and surface wetting is significantly facilitated by bubble behavior. Based on the observed phenomenon and physical mechanism, dry-out depth and initial dry-out rate are proposed to evaluate film covering potential on a heating surface. A model to predict film coverage rate is proposed based on the data. The findings would have reliable guide and important implications for further evaluation and design of decay heat removal system of new reactors, and could be helpful for passive containment cooling research.

Polydopamine/β-cyclodextrin/coal fly ash composite for the highly efficient extraction of uranium from water environment

Yan Wang,Yong Zhang,Xiaolin Liu,Sen Sun,Shiyi Qin,Jiaqi Huang,Bowei Chen 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

To obtain a green, low-cost and efficient adsorbent, polydopamine (PDA) and b-cyclodextrin (b-CD) wereadopted to modify coal fly ash (CFA) to prepare polydopamine/b-cyclodextrin/coal fly ash composite(PDA/b-CD/CFA). The successful introduction of PDA and b-CD was proved by FT-IR, XRD and XPS. Theuranium extraction efficiency on PDA/b-CD/CFA reached 95.6% (pH = 5.0, T = 298 K, C0 = 10 mg/L andm/V = 0.2 g/L) and the whole adsorption process was perfectly fitted by the Pseudo-second-order model(R2 = 0.999), illustrating that uranium was extracted via chemisorption. The correlation coefficient R2 ofLangmuir model was 0.999, which was higher than other models, meaning that uranium extractionbehavior on PDA/b-CD/CFA was uniform monolayer adsorption. The maximum extraction capacity of uraniumon PDA/b-CD/CFA calculated by Langmuir model was 537.6 mg/g, which was larger than most ofreported adsorbents, indicating that PDA/b-CD/CFA was a potential candidate for uranium extractionfrom water environment. Moreover, PDA/b-CD/CFA performed excellent uranium extraction propertieswith the existence of coexisting ions and the desorption efficiency of uranium by PDA/b-CD/CFA washigher to 95.8% at the fifth cycles, fully suggesting that PDA/b-CD/CFA possessed good selectivity andcycle stability. Characterization results demonstrated that uranium was immobilized on PDA/b-CD/CFAthrough chelation, complexing action, electrostatic interaction and hydrogen bonding.

Performance Analysis of Full-Duplex Relay Networks with Residual Self-Interference and Crosstalk

( Guoling Liu ),( Wenjiang Feng ),( Bowei Zhang ),( Tengda Ying ),( Luran Lu ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.10

This paper investigates the error performance of the amplify-and-forward (AF) relaying systems in the context of full-duplex (FD) communication. In addition to the inherent self-interference (SI) due to simultaneous transmission and reception, coexistent FD terminals may cause crosstalk. In this paper, we utilize the information exchange via the crosstalk channel to construct a particular distributed space-time code (DSTC). The residual SI is also considered. Closed-form pairwise error probability (PEP) is first derived. Then we obtain the upper bound of PEP in high transmit power region to provide more insights of diversity and coding gain. The proposed DSTC scheme can attain full cooperative diversity if the variance of SI is not a function of the transmit power. The coding gain can be improved by lengthening the frame and proper power control. Feasibility and efficiency of the proposed DSTC are verified in numerical simulations.

Degrees of Freedom of Multi-Cell MIMO Interference Broadcast Channels With Distributed Base Stations

( Hongbing Huang ),( Junyi Liu ),( Yi Zhang ),( Qing Cai ),( Bowei Zhang ),( Fengwen Jiang ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.2

In this paper, we investigate the degrees of freedom (DoF) of a multi-cell multi-user multiple-input multiple-output (MIMO) interference broadcast channel (IBC) with non-cooperation distributed base stations (BS), where each BS serves users of its corresponding cell. When all BSs simultaneously transmit their own signals over the same frequency band in the MIMO IBC, the edge users in each cell will suffer the inter-cell interference (ICI) and inter-user interference (IUI) signals. In order to eliminate the ICI and IUI signals, a distributed space time interference alignment (DSTIA) approach is proposed where each BS has only limited access to distributed moderately-delay channel state information at the transmitter (CSIT). It is shown that the DSTIA scheme can obtain the appreciate DoF gains. In addition, the DoF upper bound is asymptotically achievable as the number of antenna at each BS increases. It is shown that the DSTIA method can get DoF gains over other interference alignment schemes with delayed CSIT in literature. Moreover, the DSTIA method can attain higher DoFs than the IA schemes with global CSIT for certain antenna configurations.

Molecular design of a wide-band-gap conjugated polymer for efficient fullerene-free polymer solar cells

Liu, Delong,Yang, Bei,Jang, Bomee,Xu, Bowei,Zhang, Shaoqing,He, Chang,Woo, Han Young,Hou, Jianhui The Royal Society of Chemistry 2017 ENERGY AND ENVIRONMENTAL SCIENCE Vol.10 No.2

<P>Two p-type conjugated polymers with disparate optical and electronic properties, PB3T and PB2T, were developed and applied in fullerene-free polymer solar cells (PSCs). The photovoltaic performance of the PB3T-based PSC device processed by anisole achieved a high power conversion efficiency of 11.9% with a <I>J</I>sc of 18.8 mA cm<SUP>−2</SUP> and <I>V</I>oc of 1.00 V.</P>