Dilute Magnetic Semiconductor and Half-Metal Behaviors in 3 <i>d</i> Transition-Metal Doped Black and Blue Phosphorenes: A First-Principles Study

Yu, Weiyang,Zhu, Zhili,Niu, Chun-Yao,Li, Chong,Cho, Jun-Hyung,Jia, Yu Springer US 2016 NANOSCALE RESEARCH LETTERS Vol.11 No.1

<P>We present first-principles density-functional calculations for the structural, electronic, and magnetic properties of substitutional 3<I>d</I> transition metal (TM) impurities in two-dimensional black and blue phosphorenes. We find that the magnetic properties of such substitutional impurities can be understood in terms of a simple model based on the Hund’s rule. The TM-doped black phosphorenes with Ti, V, Cr, Mn, Fe, and Ni impurities show dilute magnetic semiconductor (DMS) properties while those with Sc and Co impurities show nonmagnetic properties. On the other hand, the TM-doped blue phosphorenes with V, Cr, Mn, and Fe impurities show DMS properties, with Ni impurity showing half-metal properties, whereas Sc- and Co-doped systems show nonmagnetic properties. We identify two different regimes depending on the occupation of the hybridized electronic states of TM and phosphorous atoms: (i) bonding states are completely empty or filled for Sc- and Co-doped black and blue phosphorenes, leading to nonmagnetic; (ii) non-bonding <I>d</I> states are partially occupied for Ti-, V-, Cr-, Mn-, Fe- and Ni-doped black and blue phosphorenes, giving rise to large and localized spin moments. These results provide a new route for the potential applications of dilute magnetic semiconductor and half-metal in spintronic devices by employing black and blue phosphorenes.</P><P><B>PACS numbers:</B> 73.22.-f, 75.50.Pp, 75.75. + a</P>

Anomalous doping effect in black phosphorene using first-principles calculations

Yu, Weiyang,Zhu, Zhili,Niu, Chun-Yao,Li, Chong,Cho, Jun-Hyung,Jia, Yu The Royal Society of Chemistry 2015 Physical chemistry chemical physics Vol.17 No.25

<P>Using first-principles density functional theory calculations, we investigate the geometries, electronic structures, and thermodynamic stabilities of substitutionally doped phosphorene sheets with group III, IV, V, and VI elements. We find that the electronic properties of phosphorene are drastically modified by the number of valence electrons in dopant atoms. The dopants with an even number of valence electrons enable the doped phosphorenes to have a metallic feature, while the dopants with an odd number of valence electrons retain a semiconducting feature. This even–odd oscillating behavior is attributed to the peculiar bonding characteristics of phosphorene and the strong hybridization of sp orbitals between dopants and phosphorene. Furthermore, the calculated formation energies of various substitutional dopants in phosphorene show that such doped systems can be thermodynamically stable. These results propose an intriguing route to tune the transport properties of electronic and photoelectronic devices based on phosphorene.</P> <P>Graphic Abstract</P><P>Using first-principles density functional theory calculations, we investigate the geometries, electronic structures, and thermodynamic stabilities of substitutionally doped phosphorene sheets with group III, IV, V, and VI elements. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5cp01732g'> </P>

Clustering and Recommendation for Semantic Web Service in Time Series

( Yu Lei ),( Wang Zhili ),( Meng Luoming ),( Qiu Xuesong ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.8

Promoted by cloud technology and new websites, plenty and variety of Web services are emerging in the Internet. Meanwhile some Web services become outdated even obsolete due to new versions, and a normal phenomenon is that some services work well only with other services of older versions. These laggard or improper services are lowering the performance of the composite service they involved in. In addition, using current technology to identify proper semantic services for a composite service is time-consuming and inaccurate. Thus, we proposed a clustering method and a recommendation method to deal with these problems. Clustering technology is used to classify semantic services according to their topics, functionality and other aspects from plenty of services. Recommendation technology is used to predict the possible preference of a composite service, and recommend possible component services to the composite service according to the history information of invocations and similar composite services. The experiments show that our clustering method with the help of Ontology and TF/IDF technology is more accurate than others, and our recommendation method has less average error than others in the series of missing rate.

Steganalysis of Synonym-Substitution Based Natural Language Watermarking

Zhenshan Yu,Liusheng Huang,Zhili Chen,Lingjun Li,Xinxin Zhao,Youwen Zhu 보안공학연구지원센터 2009 International Journal of Multimedia and Ubiquitous Vol.4 No.2

Natural language watermarking (NLW) is a kind of digital rights management (DRM) techniques specially designed for natural language documents. Watermarking algorithms based on synonym substitution are the most popular kind, they embeds watermark into documents in linguistic meaning-preserving ways. A lot of work has been done on embedding, but only a little on steganalysis such as detecting, destroying, and extracting the watermark. In this paper, we try to distinguish between watermarked articles and unwatermarked articles using context information. We evaluate the suitability of words for their context, and then the suitability sequence of words leads to the final judgment made by a SVM (support vector machine) classifier. IDF (inverse document frequency) is used to weight words’ suitability in order to balance common words and rare ones. This scheme is evaluated on internet instead of in a specific corpus, with the help of Google. Experimental results show that classification accuracy achieves 90.0%. And further analysis of several influencing factors affecting detection effects is also presented.

Multivalency-Driven Formation of Te-Based Monolayer Materials: A Combined First-Principles and Experimental study

Zhu, Zhili,Cai, Xiaolin,Yi, Seho,Chen, Jinglei,Dai, Yawei,Niu, Chunyao,Guo, Zhengxiao,Xie, Maohai,Liu, Feng,Cho, Jun-Hyung,Jia, Yu,Zhang, Zhenyu American Physical Society 2017 Physical Review Letters Vol.119 No.10

<P>Contemporary science is witnessing a rapid expansion of the two-dimensional (2D) materials family, each member possessing intriguing emergent properties of fundamental and practical importance. Using the particle-swarm optimization method in combination with first-principles density functional theory calculations, here we predict a new category of 2D monolayers named tellurene, composed of the metalloid element Te, with stable 1T-MoS2-like (alpha-Te), and metastable tetragonal (beta-Te) and 2H-MoS2-like (gamma-Te) structures. The underlying formation mechanism is inherently rooted in the multivalent nature of Te, with the central-layer Te behaving more metal-like (e.g., Mo), and the two outer layers more semiconductorlike (e.g., S). We also show that the alpha-Te phase can be spontaneously obtained from the magic thicknesses divisible by three layers truncated along the [ 001] direction of the trigonal structure of bulk Te, and both the alpha- and alpha-Te phases possess electron and hole mobilities much higher than MoS2. Furthermore, we present preliminary but convincing experimental evidence for the layering behavior of Te on HOPG substrates, and predict the importance of multivalency in the layering behavior of Se. These findings effectively extend the realm of 2D materials to group-VI elements.</P>

A novel reliability analysis method based on Gaussian process classification for structures with discontinuous response

Yibo Zhang,Zhili Sun,Yutao Yan,Zhenliang Yu,Jian Wang 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.6

Reliability analysis techniques combining with various surrogate models have attracted increasing attention because of their accuracy and great efficiency. However, they primarily focus on the structures with continuous response, while very rare researches on the reliability analysis for structures with discontinuous response are carried out. Furthermore, existing adaptive reliability analysis methods based on importance sampling (IS) still have some intractable defects when dealing with small failure probability, and there is no related research on reliability analysis for structures involving discontinuous response and small failure probability. Therefore, this paper proposes a novel reliability analysis method called AGPC-IS for such structures, which combines adaptive Gaussian process classification (GPC) and adaptive-kernel-density-estimation-based IS. In AGPC-IS, an efficient adaptive strategy for design of experiments (DoE), taking into consideration the classification uncertainty, the sampling uniformity and the regional classification accuracy improvement, is developed with the purpose of improving the accuracy of Gaussian process classifier. The adaptive kernel density estimation is introduced for constructing the quasi-optimal density function of IS. In addition, a novel and more precise stopping criterion is also developed from the perspective of the stability of failure probability estimation. The efficiency, superiority and practicability of AGPC-IS are verified by three examples.

Fuzzy Adaptive Sliding Mode Control for the Precision Position of Piezo-Actuated Nano Positioning Stage

Jiwen Fang,Lufan Zhang,Zhili Long,Michael Yu Wang 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.10

This paper concerns hysteresis and creep of a piezo-actuated nano positioning stage. The hysteresis and creep, considered as bounded disturbance or uncertainty, are suppressed without a nonlinear model. An improved Fuzzy Adaptive Sliding Mode Control (FASMC) with a Proportional-Integral-Derivative sliding surface is designed to cancel both hysteresis and creep. However, the constant slopes of the sliding function may increase oscillations. Some variable gains with adaptive rules are introduced to overcome this drawback by changing the sliding function values online. Fuzzy control is applied to tune the switching control part to improve performance. Furthermore, an adaptation law is used to approximate the optimal value of the switching control. The stability of the sliding mode control law is proved in the sense of Lyapunov stability theorem. To eliminate chattering and obtain a smooth signal, the switching control is modified and a smooth function is introduced to substitute the signum function. An anti-saturation control is introduced to keep the input voltage within safety scope. Experimental results show that FASMC can achieve faster response for step input and sinusoid signal. Both hysteresis and creep of the piezoelectric actuator are suppressed by the proposed FASMC. Therefore, the FASMC can reduce the tracking errors of the piezo-actuated stage.

Software Pipeline–Based Partitioning Method with Trade-Off between Workload Balance and Communication Optimization

Kai Huang,Min Yu,Xiaomeng Zhang,Rongjie Yan,Xiaolang Yan,Zhili Liu,Siwen Xiu 한국전자통신연구원 2015 ETRI Journal Vol.37 No.3

For a multiprocessor System-on-Chip (MPSoC) to achieve high performance via parallelism, we must consider how to partition a given application into different components and map the components onto multiple processors. In this paper, we propose a software pipeline–based partitioning method with cyclic dependent task management and communication optimization. During task partitioning, simultaneously considering computation load balance and communication optimization can cause interference, which leads to performance loss. To address this issue, we formulate their constraints and apply an integer linear programming approach to find an optimal partitioning result — one that requires a trade-off between these two factors. Experimental results on a reconfigurable MPSoC platform demonstrate the effectiveness of the proposed method, with 20% to 40% performance improvements compared to a traditional software pipeline–based partitioning method.

Effect of Lonicera edulis polysaccharide on reducing oral dyeing of lonicera edulis juice

Wang Xin,Luo Yu,Ma Rui,Wang Zhili,Yu Shiyou,Li Chenchen,Han Chunran 한국응용생명화학회 2022 Applied Biological Chemistry (Appl Biol Chem) Vol.65 No.3

Fluorescence spectroscopy, particle size determination, and potential analysis were exploited to elucidate the effect of Lonicera edulis polysaccharide on polyphenol protein. The results revealed that Lonicera edulis polysaccharides mediated the binding of polyphenols and proteins through competition and formation of ternary complexes and were also able to enhance the stability of the polyphenol-protein complex solution system. A certain electrostatic effect was also present in the process simultaneously. As confirmed by the dyeing test, to improve oral dyeing, the optimum conditions of adding polysaccharide, pectin, and casein were as follows: the dosage of the polysaccharide group was 1.2 mg/mL, coloring time was 100 min, pH value was 4.0. Pectin group added 0.8 mg/mL with coloring time 80 min, pH 5.0. The addition of casein was 1.2 mg/mL; the coloring time was 100 min with pH 5.0. The sample juice substantiated a significant improvement in the dyeing of porcine tongue mucosa. Under the optimal conditions, microscopic observation validates that the mucosal color of the porcine tongue epidermis was closer to that of unstained porcine tongue epidermis, which significantly improved astringency and oral staining. Fluorescence spectroscopy, particle size determination, and potential analysis were exploited to elucidate the effect of Lonicera edulis polysaccharide on polyphenol protein. The results revealed that Lonicera edulis polysaccharides mediated the binding of polyphenols and proteins through competition and formation of ternary complexes and were also able to enhance the stability of the polyphenol-protein complex solution system. A certain electrostatic effect was also present in the process simultaneously. As confirmed by the dyeing test, to improve oral dyeing, the optimum conditions of adding polysaccharide, pectin, and casein were as follows: the dosage of the polysaccharide group was 1.2 mg/mL, coloring time was 100 min, pH value was 4.0. Pectin group added 0.8 mg/mL with coloring time 80 min, pH 5.0. The addition of casein was 1.2 mg/mL; the coloring time was 100 min with pH 5.0. The sample juice substantiated a significant improvement in the dyeing of porcine tongue mucosa. Under the optimal conditions, microscopic observation validates that the mucosal color of the porcine tongue epidermis was closer to that of unstained porcine tongue epidermis, which significantly improved astringency and oral staining.

The Nature of Bonding in Bulk Tellurium Composed of One-Dimensional Helical Chains

Yi, Seho,Zhu, Zhili,Cai, Xiaolin,Jia, Yu,Cho, Jun-Hyung American Chemical Society 2018 Inorganic Chemistry Vol.57 No.9

<P>Bulk tellurium (Te) is composed of one-dimensional (1D) helical chains which have been considered to be coupled by van der Waals (vdW) interactions. However, on the basis of first-principles density functional theory calculations, we here propose a different bonding nature between neighboring chains: i.e., helical chains made of normal covalent bonds are connected together by coordinate covalent bonds. It is revealed that the lone pairs of electrons of Te atoms participate in forming coordinate covalent bonds between neighboring chains, where each Te atom behaves as both an electron donor to neighboring chains and an electron acceptor from neighboring chains. This ligand-metal-like bonding nature in bulk Te results in the same order of bulk moduli along the directions parallel and perpendicular to the chains, contrasting with the large anisotropy of bulk moduli in vdW crystals. We further find that the electron effective masses parallel and perpendicular to the chains are almost the same as each other, consistent with the observed nearly isotropic electrical resistivity. It is thus demonstrated that the normal/coordinate covalent bonds parallel/perpendicular to the chains in bulk Te lead to a minor anisotropy in structural and transport properties.</P><P>Bulk tellurium (Te) is composed of one-dimensional (1D) helical chains which have been considered to be coupled by van der Waals (vdW) interactions. However, on the basis of first-principles density functional theory calculations, we here propose a different bonding nature between neighboring chains: i.e., helical chains made of normal covalent bonds are connected together by coordinate covalent bonds.</P> [FIG OMISSION]</BR>