Emergent Topological Hall Effect in La_0.7Sr_0.3MnO₃/SrIrO₃ Heterostructures

Li, Yao,Zhang, Lunyong,Zhang, Qinghua,Li, Chen,Yang, Tieying,Deng, Yu,Gu, Lin,Wu, Di American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.23

<P>Recently, perovskite oxide heterostructures have drawn great attention because multiple and complex coupling at the heterointerface may produce novel magnetic and electric phenomena that are not expected in homogeneous materials either in the bulk or in films. In this work, we report for the first time that an emergent giant topological Hall effect (THE), associated with a noncoplanar (NC) spin texture, can be induced in ferromagnetic (FM) La<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB> thin films in a wide temperature range of up to 200 K by constructing La<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB>/SrIrO<SUB>3</SUB> epitaxial heterostructures on (001) SrTiO<SUB>3</SUB> substrates. This THE is not observed in La<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB> single-layer films or La<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB>/SrTiO<SUB>3</SUB>/SrIrO<SUB>3</SUB> trilayer heterostructures, indicating the relevance of the La<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB>/SrIrO<SUB>3</SUB> interface, where the Dzyaloshinskii-Moriya interaction due to strong spin-orbital coupling in SrIrO<SUB>3</SUB> may play a crucial role. The fictitious field associated with THE is independent of temperature in La<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB>/SrIrO<SUB>3</SUB> heterostructures, suggesting that the NC spin texture may be magnetic skyrmions. This work demonstrates the feasibility of using SrIrO<SUB>3</SUB> to generate novel magnetic and transport characteristics by interfacing with other correlated oxides, which might be useful to novel spintronic applications.</P> [FIG OMISSION]</BR>

MIMO Precoding in 802.16e WiMAX

Li, Qinghua,Lin, Xintian Eddie,Zhang, Jianzhong (Charlie) The Korea Institute of Information and Commucation 2007 Journal of communications and networks Vol.9 No.2

Multiple-input multiple-output (MIMO) transmit pre-coding/beamforming can significantly improve system spectral efficiency. However, several obstacles prevent precoding from wide deployment in early wireless networks: The significant feedback overhead, performance degradation due to feedback delay, and the large storage requirement at the mobile devices. In this paper, we propose a precoding method that addresses these issues. In this approach, only 3 or 6 bits feedback is needed to select a precoding matrix from a codebook. There are fifteen codebooks, each corresponding to a unique combination of antenna configuration (up to 4 antennas) and codebook size. Small codebooks are prestored and large codebooks are efficiently computed from the prestored codebook, modified Hochwald method and Householder reflection. Finally, the feedback delay is compensated by channel prediction. The scheme is validated by simulations and we have observed significant gains comparing to space-time coding and antenna selection. This solution was adopted as a part of the IEEE 802.16e specification in 2005.

학습 환경과 숙달도에 따른 요청 화행 실현 양상 연구 - 중국인 한국어 학습자를 중심으로 -

LI QINGHUA 영남대학교 인문과학연구소 2016 人文硏究 Vol.- No.78

The paper reports on the request speech act realization patterns of Chinese Korean Learners focusing on the learning environment and the proficiencty. The group of informants totals 120, 80 for KSL and KFL learners, who got TOPIK intermediate and advanced level, 40 informants for KNS and CNS group. The instrument used is a discourse completion test. For environments, there is no distinguish from KSL and KFL learner in the low proficiency, but in the high proficency, the environments is relevant to the request speech act realization patterns. For proficiency, in the native language environment, there is no distinguish between intermediate group and advanced group, but in the target language environment, the language proficiency is relevant to the request speech act realization patterns. This result means the learner who has high Korean proficiency need to be revealed to the target language environment. 본 연구는 학습 환경과 숙달도에 따른 중국인 한국어 학습자의 요청 화행 실현 양상에 대한 연구이다. 연구 대상은 총 120명으로 학습 환경과 숙달도에 따라 한국에서 한국어를 학습하는 학습자(KSL)중 한국어능력시험(TOPIK) 중급과 고급 취득자 각각 20명씩 총 40명, 중국에서 한국어를 학습하는 학습자(KFL) 중 한국어능력시험(TOPIK) 중급과 고급 취득자 각각 20명씩 총 40명, 그리고 한국어 모국어 화자(KNS) 20명과 중국어 모국어 화자(CNS) 20명이다. 자료 수집은 담화완성형테스트(DCT)를 사용하였다. 요청 화행 전략 실현 양상에 있어 우선 학습 환경에 대한 영향을 구체적으로 정리해보면 다음과 같다. 숙달도가 낮을 경우, 학습 환경에 따라 요청 화행 전략 실현 양상에는 별 차이가 없으나, 숙달도가 높을 경우, 학습 환경이 영향을 미치는 것으로 나타났다. 숙달도에 따라 분석해 본 결과 모국어 환경에서는 숙달도에 따라 요청 화행 전략 양상에 별 차이가 없으나, 목표어 환경에서는 숙달도가 영향을 미치는 것으로 나타났다. 이는 숙달도가 높은 학습자일수록 목표어 환경에 노출될 필요성이 있음을 시사한다.

Improved Multi-objective Genetic Algorithm Based on Parallel Hybrid Evolutionary Theory

Zou Yingyong,Zhang Yongde,Li Qinghua,Jiang Jingang,Yu Guangbin 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.1

Based on the analysis on the basic principles and characteristics of the existing multi-objective genetic algorithm (MOGA), an improved multi-objective GA with elites maintain is put forward based on non-dominated sorting genetic algorithm (NSGA). NSGA-II algorithm theory and parallel hybrid evolutionary theory is described in detail. The design principle, process and detailed implementations of the improved MOGA are given. IMNSGA-II algorithm and NSGA-II algorithm are applied to test the performance of the two algorithms for different test function, experiments of example are preformed. Experimental results show that the improved MOGA achieved the optimal between the convergence and diversity.

Synthesis and characterization of a novel polymer based on anthracene moiety for organic thin film transistor

Li, Yinam,Kim, Tae-Hoon,Zhao, Qinghua,Kim, Euh-Kyung,Han, Seung-Hon,Kim, Yun-Hi,Jang, Jin,Kwon, Soon-Ki Wiley Subscription Services, Inc., A Wiley Company 2008 Journal of polymer science Part A, Polymer chemist Vol.46 No.15

<P>We have designed and synthesized a new polymer, which could be used in the organic thin film transistor (OTFT). Poly[2,6-bis(3′-dodecythiophene-2′-yl)anthracene] (PDTAn), which is composed with anthracene moiety and dodecyl alkyl thiophene, was synthesized by oxidative polymerization using iron (III) chloride. The mole ratio of FeCl<SUB>3</SUB> and monomer (4.2:1), keeping low temperature during the initiation reaction, amount of solvent, and dropping order were very important for oxidative polymerization without crosslinking. The molecular weight of the polymer (M<SUB>w</SUB>) was measured to be 40,000 with 2.85 of polydispersity index by GPC. The physical and optical properties of the polymer were characterized by differential scanning calorimetry (DSC), cyclic voltammetry (CV), and optical absorption and photoluminescence (PL) spectroscopy. A field-effect mobility of 1.1 × 10<SUP>−4</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> S<SUP>−1</SUP>, a current on/off ratio of 10<SUP>5</SUP>, and the V<SUB>th</SUB> at −15.2 V had been obtained for OTFTs using this polymer semiconductor by solution coating. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5115–5122, 2008</P> <B>Graphic Abstract</B> <P>We designed poly[2,6-bis(3′-dodecylthiophene-2′-yl)anthracene](PDTAn) which is composed with anthracene moiety and dodecyl alkyl thiophene unit for solution processable OTFT. The polymer was synthesized by oxidative polymerization using iron (III) chloride. A field-effect mobility of 1.1 × 10<SUP>−4</SUP> cm<SUP>2</SUP> V<SUP>–1</SUP> S<SUP>–1</SUP>, a current on/off ratio of 10<SUP>5</SUP> and the V<SUB>th</SUB> at −15.2 V had been obtained for OTFTs using this polymer semiconductor by solution coating. <img src='wiley_img/0887624X-2008-46-15-POLA22839-gra001.gif' alt='wiley_img/0887624X-2008-46-15-POLA22839-gra001'> </P>

Static push-out test on steel and recycled tire rubber-filled concrete composite beams

Qinghua Han,Ying Xing,Jie Xu,Zi-Lin Li 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.19 No.4

Recycled tire rubber-filled concrete (RRFC) is employed into the steel-concrete composite structures due to its good ductility and crack resistance. Push-out tests were conducted to investigate the static behavior of steel and rubber-filled concrete composite beam with different rubber mixed concrete and studs. The results of the experimental investigations show that large studs lead a higher ultimate strength but worse ductility in normal concrete. Rubber particles in RRFC were shown to have little effect on shear strength when the compressive strength was equal to that of normal concrete, but can have a better ductility for studs in rubber-filled concrete. This improvement is more obvious for the composite beam with large stud to make good use of the high strength. Besides that the uplift of concrete slabs can be increased and the quantity and width of cracks can be reduced by RRFC efficiently. Based on the test result, a modified empirical equation of ultimate slip was proposed to take not only the compressive strength, but also the ductility of the concrete into consideration.

Manipulating Root-Soil Zone Processes by Localized Nutrient Supply to Improve Nutrient Use Efficiency and Grain Yield in Maize Cropping Systems

Qinghua Ma,Hongbo Li,Jianbo Shen 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

A Joint Allocation Algorithm of Computing and Communication Resources Based on Reinforcement Learning in MEC System

( Qinghua Liu ),( Qingping Li ) 한국정보처리학회 2021 Journal of information processing systems Vol.17 No.4

For the mobile edge computing (MEC) system supporting dense network, a joint allocation algorithm of computing and communication resources based on reinforcement learning is proposed. The energy consumption of task execution is defined as the maximum energy consumption of each user's task execution in the system. Considering the constraints of task unloading, power allocation, transmission rate and calculation resource allocation, the problem of joint task unloading and resource allocation is modeled as a problem of maximum task execution energy consumption minimization. As a mixed integer nonlinear programming problem, it is difficult to be directly solve by traditional optimization methods. This paper uses reinforcement learning algorithm to solve this problem. Then, the Markov decision-making process and the theoretical basis of reinforcement learning are introduced to provide a theoretical basis for the algorithm simulation experiment. Based on the algorithm of reinforcement learning and joint allocation of communication resources, the joint optimization of data task unloading and power control strategy is carried out for each terminal device, and the local computing model and task unloading model are built. The simulation results show that the total task computation cost of the proposed algorithm is 5%-10% less than that of the two comparison algorithms under the same task input. At the same time, the total task computation cost of the proposed algorithm is more than 5% less than that of the two new comparison algorithms.

Lactobacillus delbrueckii ssp. lactis R4 Prevents Salmonella typhimurium SL1344-Induced Damage to Tight Junctions and Adherens Junctions

Qinghua Yu,Liqi Zhu,Zhisheng Wang,Pengcheng Li,Qian Yang 한국미생물학회 2012 The journal of microbiology Vol.50 No.4

Cell junctions are the gatekeepers of the paracellular route and defend the mucosal barrier. Several enteropathogenic bacteria can invade intestinal epithelial cells by targeting and damaging cell junctions. It is not well understood how Salmonella typhimurium is able to overcome the intestinal barrier and gain access to the circulation, nor is it understood how Lactobacillus prevents the invasion of S. typhimurium. Therefore, we sought to determine whether infection with S. typhimurium SL1344 could regulate the molecular composition of cell junctions and whether Lactobacillus delbrueckii ssp. lactis R4 could affect this modification. Our data demonstrated that infection of Caco-2 cells with S. typhimurium over 2 h resulted in a redistribution of claudin-1, ZO-1, occluding,and E-cadherin. Western blot analysis of epithelial cell lysates demonstrated that S. typhimurium could decrease the expression of cell junction proteins. However, L. delbrueckii ssp. lactis R4 ameliorated this destruction and induced increased expression of ZO-1, occludin, and E-cadherin relative to the levels in the control group. The results of these experiments implied that S. typhimurium may facilitate its uptake and distribution within the host by regulating the molecular composition of cell junctions. Furthermore,Lactobacillus may prevent the adhesion and invasion of pathogenic bacteria by maintaining cell junctions and the mucosal barrier.

PRODUCTS OF DIFFERENTIATION AND COMPOSITION OPERATORS FROM THE BLOCH SPACE AND WEIGHTED DIRICHLET SPACES TO MORREY TYPE SPACES

Qinghua Hu,Songxiao Li 대한수학회 2017 대한수학회지 Vol.54 No.2

In this paper, we characterize the boundedness, compactness and essential norm of products of differentiation and composition operators from the Bloch space and weighted Dirichlet spaces to analytic Morrey type spaces.