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.

Electrical Contact Characteristics of Ag-SnO₂ Materials with Increased SnO₂ Content

Pengyu Chen,Wei Liu,Yaping Wang 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.6

The electrical contact characteristics including temperature rise, contact resistance and arc erosion rate of the Ag-SnO₂ materials with increased SnO₂ content were investigated during the repeated make-and-break operations. The thickness of arcing melting layer reduces by half and the arc erosion rate decreases more than 70% under 10000 times operations at AC 10 A with the SnO₂ content increasing from 15 wt.% to 45 wt.%, on one hand, temperature rise and contact resistance increase obviously but could be reduced to the same order of conventional Ag-SnO₂ materials by increasing the contact force. The microstructure evolution and the effect of SnO₂ on the arc erosion, contact resistance were analyzed.

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.

Electrical Contact Characteristics of Ag-SnO₂ Materials with Increased SnO₂ Content

Chen, Pengyu,Liu, Wei,Wang, Yaping The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.6

The electrical contact characteristics including temperature rise, contact resistance and arc erosion rate of the $Ag-SnO_2$ materials with increased $SnO_2$ content were investigated during the repeated make-and-break operations. The thickness of arcing melting layer reduces by half and the arc erosion rate decreases more than 70% under 10000 times operations at AC 10 A with the $SnO_2$ content increasing from 15 wt.% to 45 wt.%, on one hand, temperature rise and contact resistance increase obviously but could be reduced to the same order of conventional $Ag-SnO_2$ materials by increasing the contact force. The microstructure evolution and the effect of $SnO_2$ on the arc erosion, contact resistance were analyzed.

Design and control of extractive distillation for the separation of methyl acetate-methanol-water

Honghai Wang,Pengyu Ji,Huibin Cao,Weiyi Su,Chunli Li 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.12

The azeotrope of methyl acetate methanol and water was isolated using extractive distillation with water as entrainer. The pressure-swing extractive distillation (PSED) process and vapor side-stream distillation column (VSDC) with the rectifier process were designed to separate the methyl acetate, methanol and water mixture. It was revealed that the VSDC with the rectifier process had a reduction in energy consumption than the PSED process. Four control schemes of the two process were investigated: Double temperature control scheme (CS1), QR/F feedforward control of reboiler duty scheme for PESD (CS2), QR/F feedback control scheme for VSDC (CS3), the feedback control scheme of sensitive plate temperature of side-drawing distillation column to dominate the compressor shaft speed (CS4). Feed flow and composition disturbance were used to evaluate the dynamic performance. As a result, CS4 is a preferable choice for separation of methyl acetate-methanol-water mixture. A control scheme combining the operating parameters of dynamic equipment with the control indicators of static equipment was proposed in this paper. It means using the sensitive plate temperature of side-drawing column to control the compressor shaft speed. This is a new control scheme for extractive distillation

Optimization of a double crystal monochromator

Jiang Zheng,Wang Eryan,Song Ruiqiang,Guo Siming,Wu Jinjie,Hou Dongjie,An Zhenghua,Zhou Pengyue 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.8

The double crystal diffraction structure based on Bragg diffraction is the core component of the monochromator that is widely used in synchrotron radiation beam lines and monochromatic X-ray radiation devices. The stability of monochromatic X-rays produced by using the T-structure double crystal monochromator at National Institute of Metrology was investigated experimentally. Due to its structural defects, the X-ray flux of the T-structured double crystal monochromator shows poor long-term stability. Inspired by the Channel-cut monochromator structure, we designed a new double crystal monochromator structure to improve the long-term stability of the X-ray flux. Experiments showed that the stability of the monochromatic X-ray flux for the new double crystal monochromator structure was better than 1.0%@1 h, and the energy region and flux rate of the monochromatic X-rays are significantly improved. This work provides a stable and reliable monochromatic X-ray source for the calibration of X/γ detectors such as satellite load detectors, which will contribute to the development of X/γ detection technology.

Effect of porosity gradient in cathode gas diffusion layer on electrochemical performance of proton exchange membrane fuel cells

Yang Guogang,Wang Hao,Su Fengmin,Li Shian,Zhang Guoling,Sun Juncai,Shen Qiuwan,Jiang Ziheng,Liao Jiadong,Chen Pengyu 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7

Proton exchange nembrane fuel cells (PEMFCs) are highly promising energy devices for future transportation and distributed power stations. The electrochemical performance of PEMFCs assembled with gas diffusion layer (GDL) of different porosity gradient distributions has been analyzed using the lattice Boltzmann method. A single-phase multi-component lattice Boltzmann model employing the active approach was developed to investigate the reactive gas flow within the GDL. Two types of GDLs with the same porosity, namely multilayer porosity gradient GDLs and linear porosity gradient GDLs, were generated to investigate the effect of the porosity gradient of the GDL on the electrochemical performance of PEMFC. The results show that the two types of porosity gradient GDL improve oxygen starvation problems and enhance water management, and that the GDLs with smaller porosity gradients can increase the mean current density. This paper develops the study of pore-scale analysis of PEMFC performance and can provide guidance for the design of GDL structures.

The complete mitochondrial genome of Damora sagana and phylogenetic analyses of the family Nymphalidae

Naiyi Liu,Na Li,Pengyu Yang,Chunqin Sun,Jie Fang,Shuyan Wang 한국유전학회 2018 Genes & Genomics Vol.40 No.1

The monotypic genus Damora (Nymphalidae, Heliconiinae) contains a single species, Damora sagana, which is widely distributed across southern China. Herein, its complete mitogenome was sequenced to further understand lepidopteran mitogenome characteristics, reconstruct the nymphalid family phylogeny, and infer the subdivision of Heliconiinae species. The circular mitogenome was 15,151 bp long, abundant in A and T, and comprised of 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and one control region with a gene arrangement typical of lepidopteran mitogenomes. ATN codons initiated all PCGs, except cytochrome c oxidase subunit 1 (COX1), which was initiated by a CGA sequence as has been observed in other lepidopterans. Three PCGs (COX1, COX2 and ND4) employed a single T termination signal, whereas others had the typical complete termination codon (TAA). All tRNA genes were folded into the typical cloverleaf structure except for tRNA-Ser (AGN). The A+T-rich region included the conserved motif ‘ATAGA’ followed by a 17 bp poly-T stretch, which was also observed in tribe Argynnini mitogenomes. A phylogenetic tree was constructed via multiple methods using the 13 PCGs data of D. sagana and other available mitogenomes of nymphalid species. All three phylogenetic trees yielded the same topology. These results were consistent with those from previous studies of most major nymphalid groups, except those regarding tribe subdivision in certain subfamilies such as Argynnini + (Acraeini + Heliconiini) for Heliconiine. Furthermore, our analyses identified that the genus Cethosia was grouped with the genus Acraea composing the tribe Acraeini with strong support.

Identification of Hub Genes in the Pathogenesis of Ischemic Stroke Based on Bioinformatics Analysis

Xitong Yang,Shanquan Yan,Pengyu Wang,Guangming Wang 대한신경외과학회 2022 Journal of Korean neurosurgical society Vol.65 No.5

Objective : The present study aimed to identify the function of ischemic stroke (IS) patients’ peripheral blood and its role in IS, explore the pathogenesis, and provide direction for clinical research progress by comprehensive bioinformatics analysis. Methods : Two datasets, including GSE58294 and GSE22255, were downloaded from Gene Expression Omnibus database. GEO2R was utilized to obtain differentially expressed genes (DEGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs were performed using the database annotation, visualization and integrated discovery database. The protein-protein interaction (PPI) network of DEGs was constructed by search tool of searching interactive gene and visualized by Cytoscape software, and then the Hub gene was identified by degree analysis. The microRNA (miRNA) and miRNA target genes closely related to the onset of stroke were obtained through the miRNA gene regulatory network. Results : In total, 36 DEGs, containing 27 up-regulated and nine down-regulated DEGs, were identified. GO functional analysis showed that these DEGs were involved in regulation of apoptotic process, cytoplasm, protein binding and other biological processes. KEGG enrichment analysis showed that these DEGs mediated signaling pathways, including human T-cell lymphotropic virus (HTLV)-I infection and microRNAs in cancer. The results of PPI network and cytohubba showed that there was a relationship between DEGs, and five hub genes related to stroke were obtained : SOCS3, KRAS, PTGS2, EGR1, and DUSP1. Combined with the visualization of DEG-miRNAs, hsa-mir-16-5p, hsa-mir-181a-5p and hsa-mir-124-3p were predicted to be the key miRNAs in stroke, and three miRNAs were related to hub gene. Conclusion : Thirty-six DEGs, five Hub genes, and three miRNA were obtained from bioinformatics analysis of IS microarray data, which might provide potential targets for diagnosis and treatment of IS.

Hydraulic and Mechanical Coupling Analysis of Rough Fracture Network under Normal Stress and Shear Stress

Tianjiao Yang,Shuhong Wang,Pengyu Wang,Ze Zhang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2

The hydraulic and mechanical coupling characteristics of fracture networks under normal stress and shear stress were studied in this paper. The hydraulic and mechanical coupling model of the fracture network comprehensively considers the normal stress, shear stress, seepage pressure and roughness characteristics. Based on the boundary conditions and reasonable assumptions, COMSOL Multiphysics software was used to develop the hydraulic and mechanical coupling finite element model of the fracture network with different intersection points under normal stress and shear stress, focusing on the study of the effect of normal stress and shear stress on the fracture permeability. The degree of permeability change caused by the normal stress and shear stress is different. The shear stress has a significant influence on the fracture permeability, and when the normal stress is low, the relationship between the fracture permeability and shear stress can be described by a linear relationship. Then, the influence of the number of intersection points in the fracture network on the average fracture width, average water pressure, average seepage velocity and seepage passage of the fractured rock mass was analyzed. The number of intersections in the fracture network has little influence on the average fracture gap width and average water pressure but has a great influence on the flow velocity. The analysis in this paper is very helpful to understand the seepage characteristics in rough fractures under normal stress and shear stress.