High Step-Up, High Power Density Boost Converter Integrated with Switched Capacitor-Diode Cell

Yafei Hu,Adrian Ioinovici 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

A large dc conversion ratio non-isolated hybrid converter is obtained by integrating a capacitor-diode cell into a boost circuit. A larger conversion ratio comparing with the conventional boost converter is obtained. And the cost for this larger dc gain is just one additional cell formed by a diode and a capacitor. The new structure presents a minimum of components, positioned in such a way as to decrease the size of the capacitors. A high power density is obtained due to the use of smaller size capacitors. The single active switch is placed with the source referenced to the ground, rendering simplicity in its driving. The theory, simulation and experimental results showed a reduced voltage stress on the switches and a high efficiency.

Investigation of the strength of concrete-like material with waste rock and aeolian sand as aggregate by machine learning

Hu Yafei,Li Keqing,Zhang Bo,Han Bin 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.5

Solid waste filling is an important development direction for filling mining technology. This paper proposes to use waste rock and aeolian sand as aggregates to fill the underground extraction area in order to reduce the environmental damage of related waste solid. The experiments are optimized by response surface methodology and multivariate nonlinear response models are constructed to investigate the effects of different factors on uniaxial compressive strength (UCS) of concrete-like material (CLM). The performance of different swarm intelligence optimization algorithms is analyzed and combined with support vector regression model (SVR) to construct an intelligent prediction model for UCS. The results show that the packing density has a maximum value of 0.74 when the proportion of waste rock is around 0.6. The response model constructed in this paper has a P-value < 0.01 and R2 > 0.8, which indicates its high significance and goodness of fit. The UCS of CLM increases with the increase of cement content and slurry mass fraction, while it also increases and then decreases with the increase of proportion of waste rock. The ratio of waste rock and aeolian sand will affect the compactness of cemented structure. The better the ratio, the higher the average grey value of the cemented structure, the more compactness the cemented structure. The whale optimization algorithm-SVR model constructed in this paper has a prediction accuracy of more than 99% for UCS of CLM, which achieves high accuracy and fast prediction of UCS under multifactor conditions.

Efficient removal of methylene blue in aqueous solution by freeze-dried calcium alginate beads

Yafei Zhao,Hongsong Zhang,Guangxue Liu,Zonggao Hu,Rouwen Guan,Bing Zhang 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.11

Novel porous calcium alginate beads were prepared via crosslinking of calcium followed by freeze drying for investigating the adsorption performance for methylene blue. These beads possessed reduced shrinkage, highly porous lamellar structure and high specific surface area, and exhibited enhanced adsorption capacity and much faster adsorption rate compared to the non-porous beads obtained with conventional oven drying method. Methylene blue adsorption capacity increased with increasing of initial concentration and pH, while decreased with increasing of temperature. The adsorption process fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm. The maximum adsorption capacity was 961.5mg g−1 at 298.15 K. After eight successive adsorption-desorption cycles, the adsorption capacity had negligible decrease. Owing to the high adsorption capability, rapid adsorption rate, easy recovery and reusability, the freeze-dried beads imply a prospective, biodegradable and attractive adsorbent for removing contaminants from wastewater.

Asymmetry of Cloud Vertical Structures and Associated Radiative Effects in Typhoon over the Northwest Pacific Based on CloudSat Tropical Cyclone Dataset

Yan Yafei,Tan Jianguo,Cui Linli,Yu Wei,Hu Yan 한국기상학회 2020 Asia-Pacific Journal of Atmospheric Sciences Vol.56 No.4

The clouds’ macro-, microphysical vertical structures and radiative effects in 4 shear-relative quadrants of typhoon over the northwest Pacific during development, maturity and extinction stages are studied based on CloudSat Tropical Cyclone dataset and China Meteorological Administration tropical cyclone dataset from 2nd June 2006 to 31th December 2015. The typhoon cloud is in an asymmetric “mushroom” shape, with the downshear quadrants (in particular of the downshear left quadrant (DL)) have denser clouds than the upshear quadrants. Cloud ice water content mainly distributes near typhoon center with wide vertical range (6–17 km). A large number of ice particles with small sizes are gathering in high levels, while small amount of ice particles with large sizes are gathering in low levels. As typhoon matures, the number concentration and size of cloud ice particles in inner ring increases, especially in the DL quadrant; while in the upshear left (UL) quadrant, a larger amount of ice particles with bigger sizes are transport to high levels (above 16 km) by deeper convection near storm center. The shortwave (longwave) cloud radiative effects (CRE) is mainly heating (cooling) upper layer atmosphere between 10 km and 17 km (between 14 km and 17 km), and the net CRE on atmosphere is heating almost at any levels in typhoon. The strongest heating of shortwave CRE and net CRE, as well as the strongest cooling of longwave CRE are in the DL quadrant at development stage and in the UL quadrant at maturity stage in inner core of storms. The existences of typhoon clouds mainly decrease solar radiation penetrating to the earth surface and increase longwave radiation absorbed by the whole atmosphere in typhoon’s inner core, and they are generally stronger in downshear (especially in DL) quadrants, except the maturity stage when the UL quadrant performs the strongest shortwave CRE on the surface and longwave CRE on the atmosphere in typhoon’s inner core.

Image Fusion and Evaluation by using Mapping Satellite-1 Data

Huang, He,Hu, Yafei,Feng, Yi,Zhang, Meng,Song, DongSeob Korean Society of Surveying 2013 한국측량학회지 Vol.31 No.6

China's Mapping Satellite-1, developed by the China Aerospace Science and Technology Corporation (CASC), was launched in three years ago. The data from Mapping Satellite-1 are able to use for efficient surveying and geometric mapping application field. In this paper, we fuse the panchromatic and multispectral images of Changchun area, which are obtained from the Mapping Satellite-1, the one that is the Chinese first transmission-type three-dimensional mapping satellite. The four traditional image fusion methods, which are HPF, Mod.IHS, Panshar and wavelet transform, were used to approach for effectively fusing Mapping Satellite-1 remote sensing data. Subsequently we assess the results with some commonly used methods, which are known a subjective qualitative evaluation and quantitative statistical analysis approach. Consequently, we found that the wavelet transform remote sensing image fusion is the optimal in the degree of distortion, the ability of performance of details and image information availability among four methods. To further understand the optimal methods to fuse Mapping Satellite-1 images, an additional study is necessary.

Image Fusion and Evaluation by using Mapping Satellite-1 Data

He Huang,Yafei Hu,Yi Feng,Meng Zhang,DongSeob Song 한국측량학회 2013 한국측량학회지 Vol.31 No.6-2

Image Fusion and Evaluation by using Mapping Satellite-1 Data

He Huang,Yafei Hu,Yi Feng,Meng Zhang,송동섭 한국측량학회 2013 한국측량학회지 Vol.31 No.6

China’s Mapping Satellite-1, developed by the China Aerospace Science and Technology Corporation (CASC),was launched in three years ago. The data from Mapping Satellite-1 are able to use for efficient surveyingand geometric mapping application field. In this paper, we fuse the panchromatic and multispectral images ofChangchun area, which are obtained from the Mapping Satellite-1, the one that is the Chinese first transmissiontypethree-dimensional mapping satellite. The four traditional image fusion methods, which are HPF, Mod.IHS,Panshar and wavelet transform, were used to approach for effectively fusing Mapping Satellite-1 remote sensingdata. Subsequently we assess the results with some commonly used methods, which are known a subjectivequalitative evaluation and quantitative statistical analysis approach. Consequently, we found that the wavelettransform remote sensing image fusion is the optimal in the degree of distortion, the ability of performance ofdetails and image information availability among four methods. To further understand the optimal methods tofuse Mapping Satellite-1 images, an additional study is necessary.

Shear Behavior of Corroded Post-Tensioned Prestressed Concrete Beams with Full/Insufficient Grouting

Lei Wang,Zhuo Hu,Ju Yi,Lizhao Dai,Yafei Ma,Xuhui Zhang 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.6

This paper experimentally studied the shear behavior of corroded post-tensioned prestressed concrete beams with full grouting. The effects of insufficient grouting in shear span on the shear behavior were also investigated. Eight beams were fabricated and divided into two groups: four beams with full grouting and four beams with insufficient grouting. Three beams in each group were subjected to accelerated corrosion. All beams were tested to failure in four-point loading. Experimental data on shear cracking, load-deflection response, shear strength and failure modes were presented. Results showed that strand corrosion accelerated the formation and propagation of diagonal crack. Insufficient grouting decreased the number of diagonal cracks. Strand corrosion degraded the post-cracking stiffness and shear strength. Insufficient grouting aggravated the propagation of diagonal crack and the degradation of post-cracking stiffness. The shear strength of corroded beam with 31.7% corrosion loss decreased by 15.44% as compared to that of the uncorroded beam. Strand corrosion loss less than 31.7% did not change the shear compression failure mode in fully grouted beams. The failure modes of locally ungrouted beams changed from shear compression failure to rupture of wires as the corrosion loss exceeded 39.6%.

Mechanical Properties of (Ce + Yb) Modified in situ TiB2/Al-Si Matrix Composites Enhanced via Thermal Deformation Combined with Heat Treatment

Mingkun Qiu,Wenru Hu,Hao Liu,Yafei Pang,Xiaodong Du 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10

In the current work, the microstructure evolution and mechanical properties of (Ce + Yb) modified in situ TiB2/Al-Si matrix composite were systematically investigated by thermal deformation at strain rates of 0.0005–0.0125 s− 1 and temperatures of 250–450 °C. The enhanced strength and plasticity of the composite have a good correlation with the microstructure evolution under different thermal deformation parameters. The obtained results indicated that under the hot deformation parameters of strain rate of 0.0025 s− 1 and deformation temperature of 250 °C, the defects of micropores can be reduced or even eliminated and improved the density of the composite. The coarse α-Al grains, eutectic Si and Fe-rich phases and undissolved primary (Ce + Yb)-containing intermetallics were significantly refined under high shear stress. At the same time, the distribution of in-situ synthesized submicron TiB2 particles in the Al matrix tends to be more uniform. The substructures such as high density dislocations and low angle grain boundaries were introduced under the thermal deformation of 250 °C/0.0025 s− 1, which provided the necessary conditions for the formation of recrystallized grains that are less likely to overgrow and further promoted the aging precipitation of nano-strengthening precipitates. Finally, the UTS, YS and elongation of the composite reached the maximum values of 385 MPa, 316 MPa and 9.6% respectively, which were 60.4%, 85.9% and 45.5% higher than the as-cast and undeformed composite.

Quantitative trait locus mapping and genomic selection of tobacco (Nicotiana tabacum L.) based on high-density genetic map

Tong Zhijun,Xiu Zhihui,Ming Yao,Fang Dunhuang,Chen Xuejun,Hu Yafei,Zhou Juhong,He Weiming,Jiao Fangchan,Zhang Chi,Zhao Shancen,Jin Han,Jian Jianbo,Xiao Bingguang 한국식물생명공학회 2021 Plant biotechnology reports Vol.15 No.6

Tobacco ( Nicotiana tabacum L.) is an economic crop and a model organism for studies of plant biology and genetics. As an allotetraploid plant generated from interspecific hybridization, tobacco has a massive genome (4.5 Gb). Recently, a genetic map with 45,081 single nucleotide polymorphism (SNP) markers was constructed using whole-genome sequencing data for a tobacco population including 274 individuals. This provides a basis for quantitative trait locus (QTL) mapping and genomic selection, which have been widely applied to other crops but have not been feasible in tobacco. Based on this high-density genetic map, we identified QTLs associated with important agronomic traits, chemical compounds in dry leaves, and hazardous substances in processed cigarettes. The LOD values for major QTLs were highest for agronomic traits, followed by chemical compounds and hazardous substances. In addition to the identification of molecular markers, we evaluated genomic selection models and found that BayesB had the highest prediction accuracy for the recombinant inbred line population. Our results offer new insights into the genetic mechanism underlying important traits, such as agronomic traits and quality-related chemical compounds in tobacco, and will be able to support the application of molecular breeding to tobacco.