Motion blur processing method for visual SLAM system based on local residual blur discrimination network

Jiahao Chen,Yehu Shen,Qixin Zhu,Quansheng Jiang,Ou Xie,Jing Miao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

In visual simultaneous localization and mapping (vSLAM) systems, motion blur often leads to insufficient number of matched features, resulting in tracking failure. Existing solutions often tackle this problem by restoring sharp images from blurry ones. However, the computational costs are high, and the restored sharp images are usually distorted. The effect of blurry image sequences to vSLAM system is analyzed, and the relationships between feature matching and motion blur are acquired to deal with the above mentioned problems. A local residual motion blur discrimination network is proposed to detect images with motion blur efficiently. Motion blur recognition results are coupled with a vSLAM system so that the feature extraction process is guided by the results from the local residual motion blur discrimination network. The performance of the vSLAM system can be effectively enhanced when it is applied to sequences with motion blur. Experimental results on the Technische Universität München dataset show that the proposed algorithm increases the average tracking length by about 200 frames compared with the original method on some image sequences with violent motions. This algorithm effectively improves the stability and accuracy of the vSLAM system.

A hybrid neutronics method with novel fission diffusion synthetic acceleration for criticality calculations

Chen Jiahao,Hou Jason,Ivanov Kostadin 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.4

A novel Fission Diffusion Synthetic Acceleration (FDSA) method is developed and implemented as a part of a hybrid neutronics method for source convergence acceleration and variance reduction in Monte Carlo (MC) criticality calculations. The acceleration of the MC calculation stems from constructing a synthetic operator and solving a low-order problem using information obtained from previous MC calculations. By applying the P1 approximation, two correction terms, one for the scalar flux and the other for the current, can be solved in the low-order problem and applied to the transport solution. A variety of one-dimensional (1-D) and two-dimensional (2-D) numerical tests are constructed to demonstrate the performance of FDSA in comparison with the standalone MC method and the coupled MC and Coarse Mesh Finite Difference (MC-CMFD) method on both intended purposes. The comparison results show that the acceleration by a factor of 3–10 can be expected for source convergence and the reduction in MC variance is comparable to CMFD in both slab and full core geometries, although the effectiveness of such hybrid methods is limited to systems with small dominance ratios.

Growth behavior and corrosion resistance of graphene oxide/MgAl Layered double hydroxide coating grown on micro-arc oxidation film of magnesium alloys

Yanning Chen,Liang Wu,Wenhui Yao,Jiahao Wu,Yuan Yuan,Bin Jiang,FuSheng Pan 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-

The MgAl Layered double hydroxides (LDHs)/graphene oxide (GO) composite film was fabricated in situon the micro-arc oxidation (MAO) film (MAO/LG) of AZ31 magnesium alloy in one step by hydrothermalchemical conversion method. The growth behavior and corrosion properties of LG films were investigated. The results show that the chemical structure, composition and morphology of the LG film willgradually change with the extension of the hydrothermal treatment time based on using the selfdissolvedcation (Mg2+ and Al3+) in the MAO film as the source of growing LDHs without introducingany external metal cations. The potentiodynamic polarization showed that the MAO/LG-12 h coating(1.28 109 A/cm2) after in situ growth for 12 h was more corrosion resistant than the MAO coating(8.49 106 A/cm2). The synergistic effect of GO and LDHs can significantly improve the corrosion protectionability of MAO coating. In addition, the transition process of the growth behavior of the LG filmlayer on the MAO coating is explained in detail.

Stability study on tenon-connected SHS and CFST columns in modular construction

Yisu Chen,Chao Hou,Jiahao Peng 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.2

Modular construction is an emerging technology to accommodate the increasing restrictions in terms of construction period, energy efficiency and environmental impacts, since each structural module is prefabricated offsite beforehand and assembled onsite using industrialized techniques. However, some innate structural drawbacks of this innovative method are also distinct, such as connection tying inaccessibility, column instability and system robustness. This study aims to explore the theoretical and numerical stability analysis of a tenon-connected square hollow section (SHS) steel column to address the tying and stability issue in modular construction. Due to the excellent performance of composite structures in fire resistance and buckling prevention, concrete-filled steel tube (CFST) columns are also taken into account in the analysis to evaluate the feasibility of adopting composite sections in modular buildings. Characteristic equations with three variables, i.e., the length ratio, the bending stiffness ratio and the rotational stiffness ratio, are generated from the fourth-order governing differential equations. The rotational stiffness ratio is recognized as the most significant factor, with interval analysis conducted for its mechanical significance and domain. Numerical analysis using ABAQUS is conducted for validation of characteristic equations. Recommendations and instructions in predicting the buckling performance of both SHS and CFST columns are then proposed.

Investigating the Characteristics of Wet Shotcrete Pipeline Transportation

Lianjun Chen,Jiahao Sun,Xiaohan Guo,Nan Guo,Yanan Huang,Guoming Liu 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.12

In order to study the resistance characteristics of wet shotcrete pipeline transportation, a small pipe type rheology and resistance test device was developed. The device is used for straight pipe resistance test, pump stop test and dyed concrete test were carried out on concrete with different characteristics. The fluidity changes of concrete with different characteristics were obtained through experiments. The results show that the slump, pressure bleeding rate, water-cement ratio were all negatively related to pipeline transportation resistance. The influence of the three factors on resistance was in order: pressure bleeding rate, water-cement ratio, slump. The dyed concrete test confirmed the principle of the plunger flow in the pipeline when concrete is pumped. The thickness of the lubricating layer increased with the increase of the water-cement ratio. The concrete pipeline transportation resistance increased with the increase of the standing time. The fitting curve was obtained through the correlation analysis between resistance and lubricating layer thickness, and the two were negatively correlated. This provides a new research idea for the study of drag reduction measures for concrete pipeline transportation.

Genome‑wide identification of GMP genes in Rosaceae and functional characterization of FaGMP4 in strawberry (Fragaria × ananassa)

Yuanxiu Lin,Jiahao Zhang,Lintai Wu,Yunting Zhang,Qing Chen,Mengyao Li,Yong Zhang,Ya Luo,Yan Wang,Xiaorong Wang,Haoru Tang 한국유전학회 2021 Genes & Genomics Vol.43 No.6

Background GDP-D-mannose pyrophosphorylase (GMP) is one of the key enzymes determining ascorbic acid (AsA) biosynthesis. However, little information about GMP genes is currently available for the Rosaceae species, especially in the AsA-riched cultivated octoploid strawberry (Fragaria × ananassa). Objective To identify the all the GMP genes in Rosaceae, as well as the predominant homologues and the role of GMP genes in strawberry AsA accumulation. Methods In the present study, we performed genome-wide identifcation and comprehensive analysis of the duplicated GMP genes in strawberry and other Rosaceae species by bioinformatics methods, the expression of the GMP genes from cultivated strawberry (Fragaria × ananassa, FaGMP) was specifcally analyzed by qPCR. Finally, the FaGMP4 was transiently overexpressed in strawberry to estimate the role of GMP in regulating AsA accumulation in strawberry. Results As results, a total of 28 GMP genes were identifed in the fve Rosaceae species. The origins of duplication events analysis suggested that most GMP duplications in Rosaceae species were generated from whole genome duplication (WGD). The Ka/Ks ratio suggested that FaGMP genes underwent a stabilization selection. qPCR based expression analysis showed diferent patterns of FaGMP paralogs during fruit ripening, while FaGMP4 expressed higher in the variety containing higher AsA. Overexpression of FaGMP4 in strawberry signifcantly enhanced AsA accumulation. Furthermore, the expression of FaGMP4 under the treatment of blue and red light was largely increased in leaves while signifcantly inhibited in fruit. These results revealed the vital role of FaGMP4 in regulating AsA in strawberry.

In-Situ Precipitated Needle Like Nanocrystalline β-Ti Reinforced Porous Titanium Alloy via Molten Salt Electrolysis

Hao Wang,Jiahao Zhao,Honglin Li,Zhifeng Huang,Yangwei Wang,Qiang Shen,Fei Chen 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1

Fabricating porous active metals through chemical dealloying poses challenges due to their reactivity and vulnerability tooxidation in aqueous solutions. The objective of this study was to create micron-sized porous Ti alloy by utilizing the Ti–Mo system as a precursor alloy for chemical dealloying. The impact of phase composition and initial microstructure of theprecursor alloys (Tix at% Mo100 − x at%, x = 60 ~ 70) on the morphology of the resulting porous Ti alloy was systematicallyinvestigated. To improve the mechanical strength and minimize oxidized phases during the dealloying process, a molten saltelectrolysis (MSE) method was employed. The strengthening mechanism of MSE on porous Ti alloys encompassed three keyaspects. Firstly, it effectively reduced the presence of oxidized phases, thereby eliminating surface defects. Secondly, MSEfacilitated grain growth and eliminated voids and cracks at the grain boundaries, leading to enhanced mechanical properties. Thirdly, the involvement of a secondary phase contributed to the overall strengthening mechanism. Following MSE treatment,the oxygen content in the porous Ti alloy decreased from over 13 to 5 at%, and needle-like nanocrystalline β-Ti precipitatesformed within the ligament structure. The accumulation and aggregation of compression-induced dislocations at the grainboundaries of the precipitated phase further improved the mechanical properties. In summary, this work presents an innovativeapproach to fabricating porous Ti alloy with low oxygen content, high strength, and adjustable microstructure. It elucidatesthe strength enhancement mechanism by MSE, providing insights for future materials development and applications.

Potato tillage method is associated with soil microbial communities, soil chemical properties, and potato yield

Ma Haiyan,Xie Chen,Zheng Shunlin,Li Peihua,Cheema Hafsa Nazir,Gong Jing,Xiang Zhuqing,Liu Juanjuan,Qin Jiahao 한국미생물학회 2022 The journal of microbiology Vol.60 No.2

Intensive potato continuous cropping (IPCC) results in low potato yields compared with non-intensive potato continuous cropping (PCC) and potato-maize rotation (PMRC). However, it is still unclear whether the degree of potato continuous cropping obstacle is related to the soil environment formed by the previous crop. To investigate the effect of planting potatoes and planting maize after harvesting the spring potatoes on soil chemical properties and soil microbial community structure, an experiment was carried out in the same origin soil environment over a period of seven years: (a) PCC, i.e., spring planting; (b) IPCC, i.e., autumn and spring planting (IPCC); (c) PMRC, i.e., spring potatoes and summer maize (PMRC), and (d) fallow (CK). We confirmed that the potato yield under PMRC was significantly higher than that under PCC and IPCC. Under IPCC, soil total phosphorus content was significantly higher than other treatments, whereas ammonium nitrogen content was the lowest. Compared with PCC and IPCC, PMRC had a higher ammonium nitrogen content and lower total phosphorus content. The significantly different fungal taxa in IPCC (Glomerellales, Plectosphaerella, Thelebolales) may threaten the health of the plant and positive correlated with soil total phosphorus, while other microbial taxa in PMRC (Bacillales, Polythrincium, Helotiales) can mainly promotes plant nitrogen uptake and protects plants against diseases. The PMRC-promoting taxa were positively correlated with the ammonium nitrogen content and negative correlated with soil total phosphorus content. In summary, the cropping systems might have affected potato yields by changed soil microorganism community structures – especially fungal community structures – and by the chemical properties of the soils that also depends on microbes.

Sensorless control for five‑phase PMSMs under normal and open‑circuit fault conditions using super‑twisting sliding mode observers

Guohai Liu,Abdallah Farahat,Qian Chen,Jiahao Zhang,Xu Wang 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.7

To enhance system position estimation reliability when a single-phase open-circuit fault occurs, this study provides a sensorless control strategy based on a medium and high-speed super-twisting sliding mode observer (ST-SMO) for a five-phase permanent magnet synchronous motor, in which the space vector pulse width modulation (SVPWM) control strategy is adopted. In this method, a super-twisting sliding mode observer is developed to achieve any two-healthy phase back electromotive force (EMFs) estimation, during normal and open-circuit fault operations, irrespective of parameter variations and external disturbances. Then a phase-locked loop (PLL) is presented to extract the position and the speed of the rotor directly from the estimated two phase back-EMFs. The proposed ST-SMO algorithm achieves strong robustness to various external variations, suppresses system chattering, and enhances the estimation accuracy in the medium and high-speed range. Simulation and experimental results are provided to verify the effectiveness of the proposed method under different load conditions over medium to high-speed ranges.

Ozone infusiblization and curing mechanism of polysilazane ceramic precursor fibers

Li Xiaohong,Luo Xiaoyu,Li Jing,Li Jinxia,Yang Jiahao,Ahmad Zahoor,Bao Zhihao,Zhang Xiao,Chen Jianjun 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.5

An appropriate infusible method plays a vital role as one of the key processes of the fabrication of polymer-derived ceramic fibers. In this work, ozone curing, a novel room temperature controllable curing strategy was used to prepare SiCN ceramic fibers. Some circular pores were observed on the surface of the obtained SiCN ceramic fibers. The tensile strength of the fibers was also investigated. To reveal the ozone-curing mechanisms of the PSZ fibers and the formation process of the circular pores, the FT-IR, SEM, OM, XRD and TG were characterized. The results showed that the Si–H bonds and Si-CH3 groups in the PSZ molecule were oxidized gradually to form oxygen-containing groups such as Si–OH, Si–O-Si and C = O in the ozone curing process, which contributed to the curing and weight gain of the PSZ fibers. Moreover, a hydrolysis reaction between Si-NH-Si and H2O might further accelerate the curing of the PSZ fibers. An unexpected result of the hydrolysis reaction is the formation of some circular pores on the surface layer of the PSZ fibers. This strategy provides a method to design, adjust and control the microstructure and composition of silicon-based ceramic fibers, and the obtained SiCN fibers may be used as catalyst support, bacterial culture and other fields.