Assembly mechanisms of soil bacterial communities in subalpine coniferous forests on the Loess Plateau, China

Pengyu Zhao,Jinxian Liu,Tong Jia,Zhengming Luo,Cui Li,Bao-Feng Chai 한국미생물학회 2019 The journal of microbiology Vol.57 No.6

Microbial community assembly is affected by trade-offs between deterministic and stochastic processes. However, the mechanisms underlying the relative influences of the two processes remain elusive. This knowledge gap limits our ability to understand the effects of community assembly processes on microbial community structures and functions. To better understand community assembly mechanisms, the community dynamics of bacterial ecological groups were investigated based on niche breadths in 23 soil plots from subalpine coniferous forests on the Loess Plateau in Shanxi, China. Here, the overall community was divided into the ecological groups that corresponded to habitat generalists, ‘other taxa’ and specialists. Redundancy analysis based on Bray-Curtis distances (db-RDA) and multiple regression tree (MRT) analysis indicated that soil organic carbon (SOC) was a general descriptor that encompassed the environmental gradients by which the communities responded to, because it can explain more significant variations in community diversity patterns. The three ecological groups exhibited different niche optima and degrees of specialization (i.e., niche breadths) along the SOC gradient, suggesting the presence of a gradient in tolerance for environmental heterogeneity. The inferred community assembly processes varied along the SOC gradient, wherein a transition was observed from homogenizing dispersal to variable selection that reflects increasing deterministic processes. Moreover, the ecological groups were inferred to perform different community functions that varied with community composition, structure. In conclusion, these results contribute to our understanding of the trade-offs between community assembly mechanisms and the responses of community structure and function to environmental gradients.

Effect of Initial Indentation Position on Plastic Deformation Behaviors of Polycrystalline Materials via Molecular Dynamics Simulation

Pengyue Zhao,Yongbo Guo 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.1

Polycrystalline materials can be divided into four types of microstructural components, including grain cell (GC), grain boundary (GB), triple junction (TJ) and vertex points (VP). Nanoindentation at different microstructural components on the polycrystalline materials surface can lead to different plastic deformation behaviors of the polycrystalline materials. Due to experimental limitations, the indentation-induced internal stress and defect evolution process are difficult to investigate directly, especially for the polycrystalline materials with grain size less than 100 nm. The molecular dynamics (MD) simulations were performed to unravel the initial indentation position effect on the elasticity/plastic deformation mechanism of polycrystalline copper. The results reveal that the initial indentation position governs the indentation force variation and defect distribution range due to the different dimensionalities of the microstructural components. The defect propagation as well as the internal stress transmission in the GC regions tend to transfer to the low-dimensional microstructural components of the interfaces. In addition, the atomic internal stress and potential energy accumulation/release of the microstructural component atoms during the nanoindentation process are also investigated, revealing that the atomic internal stress and potential energy in the VPs vary earliest, followed by the TJs, GBs and GCs.

Band Gap Modulation of Lead Sulfide QDs

Pengyu Zeng,Wei Li,Yun Zhao,Mengting Liu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.6

Lead sulfide quantum dots (QDs) were prepared by liquid phase method. The particle size can be controlled by changing the concentration of reactants and surfactant and the size of the QDs varies from 7 nm to 20 nm, which results in the change of the optical properties and the band gap of the particles. The optical band gap of lead sulfide QDs increased drastically with the decrease of the diameter of the sample QDs.

Metal Adsorbate-Induced Plasmon Damping in Gold Nanorods: The Difference Between Metals

Pengyu Xu,Xuxing Lu,Junwei Zhao,Yue Li,Sheng Chen,Junfei Xue,Weihui Ou,Song Han,YAPING DING,Weihai Ni 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.9

We presented a single particle study on the metal adsorbate-induced plasmon damping in Au nanorods (AuNRs) through adsorbing clusters of different metals including Pt, Au and Ag. AuNRs with different longitudinal surface plasmon resonance (LSPR) wavelength were measured and investigated individually. Linewidth broadening, plasmon shift and reduction of plasmonic resonance of single AuNRs were studied and compared between Pt, Au and Ag adsorbates. The measured linewidths perfectly match the theoretical predictions of the billiard model with increased scattering coefficients resulted from the metal adsorbates. The results indicate that the plasmon damping in case of Ag is significantly weaker than Pt and Au, which can be attributed to longer relaxation time of free electrons in Ag and therefore less loss of the oscillating plasmon electrons. In contrast to the red shift observed from Au and Pt, blue shift of the LSPR is observed in case of Ag. It suggests that plasmonic properties brought by the metal adsorbates can exert dramatic influence on the nanoparticle that is adsorbed with. We believe that our study not only provides important understanding on plasmon damping but pave the road for the fabrication of complex nanostructures with two or more metal elements.

Ensemble learning-based hierarchical retrieval of similar cases for site planning

Wang Pengyue,Guo Maozu,Han Yunsong,Zhao Lingling,Zhou Xiaoping,Zhang Dayu 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.6

Site planning not only involves the arrangement of a large number of elements but also considers the complexity of urban systems; hence, the design process involves large workloads and is time consuming. Retrieving similar existing cases helps architects optimize or accelerate the design process. This paper proposes a computational approach that provides valuable references by retrieving similar cases. Three types of attributes are extracted to represent a given parcel: land-use attributes, geometric attributes (area, orientation, etc.), and environmental attributes (greening rate, surrounding facilities, etc.). The complete hierarchical retrieval process is divided into three phases. The first phase selects cases whose land-use attributes are consistent with the target parcel. Then, the similarity distances between the given target parcel and the selected cases are calculated using geometric attributes. The eXtreme Gradient Boosting (XGBoost) classifier is adopted to determine which case is similar to the target parcel. Finally, similarity scores of the retrieved cases are calculated based on the environmental attributes to provide more options during the actual design. In total, 1189 cases with different land-use types in Beijing were collected for the case base. The comparative experimental results confirmed that the proposed ensemble learning-based hierarchical retrieval of similar cases approach improves the accuracy of retrieval results. Furthermore, we use a real-world target parcel to demonstrate the superiority and flexibility of the retrieval process.

Design of miniaturized and lightweight coupling inductors for interleaved parallel DC/DC converters

Wang, Yifeng,Cheng, Pengyu,Ma, Xiaoyong,Tao, Long,Zhao, Danfeng The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.10

At present, coupled inductance is an effective method for the development of the interleaved parallel converters in terms of high efficiency, miniaturization, and light weight. In view of the difficulty in designing coupling inductors in multiphase interleaved parallel converters, a general coupling inductor design criterion is proposed in this paper. First, the equivalent steady-state inductance and equivalent transient inductance expressions of a converter are obtained according to the modal transformation law of a two-phase interleaved parallel buck converter circuit. In addition, the volume modeling and weight modeling of the core are established, and expressions of the self-inductance and coupling coefficient are obtained. Then, the self-inductance and coupling coefficients are derived with the constraints of the steady-state current ripple and transient response speed as well as the objective function of the volume modeling and weight modeling. It is ensured that the designed coupled inductor successfully achieves its purposes of reducing the volume, weight, and inductor current ripple of the converter while improving the system response speed. Finally, the correctness of the theoretical analysis and the accuracy of the design method were verified on a 40 kW experimental platform based on a SiC MOSFET.

Design and Implementation of Inter-core Communication of Embedded Multiprocessor Based on Shared Memory

Yang Nie,Lili Jing,Pengyu Zhao 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.12

In this paper, two Cortex-A9 processors and microblaze processor are used to build a multiprocessor embedded system. The whole system is connected AXI Interconnect, and the shared memory is used as a communication mechanism. Embedded multiprocessor system is mapped into FPGA, and the feasibility and practicability of the system are verified. Simulation result Indicate that shared memory provides very high performance and low latency access from both processors compared with the DDR memory.

The Circuit Design of Audio Adaptive Filter via Model-Based Design

Hua Ge,Yang Nie,Lili Jing,Pengyu Zhao 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.11

In this paper, model-based design is used to complete the design of an adaptive filter by Least Mean Square (LMS) algorithm, which implements the recovery process of audio signal disturbed by noise. We can quickly build a system simulation model by model-based design approach, and accomplish efficiently the system test, simulation and implementation. Theoretical analysis and experimental results show that the method of model-based design is not only valuable to the design and implementation of DSP system, but also can significantly improve the design efficiency of the DSP system.

Preparation and properties of CNTs-Cu hybrids/epoxy superhydrophobic and anticorrosive coatings

Zhongbo Zhu,Shumei Kang,Hua Chen,Qingping Zhao,Zhaokang Huo,Pengyu Li,Qidong Cao,Chenshuo Lu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.119 No.-

In this work, hydrophobized copper powders combined siloxane-modified carbon nanotubes(SHMWCNTs) to obtain intertwined hybrids of carbon nanotubes and copper (CNTs-Cu hybrids), andsuperhydrophobic CNTs-Cu hybrids/epoxy coatings were prepared on the surface of AH36 carbon steelby drop coating. The surface morphology and wettability of coatings were changed by adjusting the ratiosof SHMWCNTs to hydrophobized copper powders. The obtained coating can show a water contact angleof 167.2, a water sliding angle of 2.9, a plant oil contact angle of 134.3, and self-cleaning properties. Thecoating maintains superhydrophobicity after 300 tape-peeling times, exhibiting excellent mechanicaldurability. The fouled area percentages of chlorella on the coating and a pure epoxy resin were 0.23(±0.07)% and 12.18(±1.22)%, respectively, displaying anti-biofouling resistances. The coating has excellentcorrosion resistance, and its corrosion current density reached 9.55 10-8 A/cm2.