A Review of Technologies for Welding Magnesium Alloys to Steels

Tianhao Wang,Piyush Upadhyay,Scott Whalen 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.3

We survey various state-of-the-art methods for welding magnesium alloys and steels using different joint configurations. Microstructural characterizations indicate that four microstructures may form at the Mg/steel interface after welding: unwelded gap, metal oxides, solid solutions, or intermetallic compounds. Reaction products at the Mg/steel interface vary with different welding methods, alloying elements in base materials, interlayers or coatings applied, and preparations of base material before welding. Mechanical property characterizations, (a) lap tensile shear testing for lap-welded and spot-welded joints, (b) tensile testing for butt-welded joints and (c) fatigue properties of lap-welded and spot-welded joints are summarized and compared, separately. Reaction products at the Mg/steel interface are correlated with mechanical properties. Finally, ways to enhance Mg/steel joint strength, such as introducing interlocking features during friction stir lap and butt welding, are discussed.

Catalytic reduction of CO2 to HCO2 by nanoscale nickel-based bimetallic alloy under atmospheric pressure

Yi Zhao,Tianhao Wang,Yongbin Wang,Runlong Hao,Han Wang,Yuhong Han 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.77 No.-

Carbon dioxide (CO2) was converted into formate (HCO2) in a catalytic reduction system mainlycomposed of potassium borohydride (KBH4) and nanoscale bimetallic nickel–copper alloy (NBN–C), inwhich, the average CO2 conversion efficiency of 41.92% was obtained under the optimal experimentalconditions, with a HCO2selectivity of 53.42%. Various characterization methods were employed toinvestigate the physicochemical properties of NBN–C and the results indicated that NBN–C was a coreshellmesoporous catalyst with key active sites containing Ni0 and Cu0, at which the catalytic reduction ofCO2 took place. The reaction mechanism was proposed based on these characterizations and relevantliteratures.

Electrically Conductive Graphene-Based Biodegradable Polymer Composite Films with High Thermal Stability and Flexibility

Xuejiao Liu,Qinfeng Zou,Tianhao Wang,Liping Zhang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.3

Cellulose nanofibril (CNF) and graphene (GR) powder were added into polylactic acid (PLA)/ polypyrrole (PPy) composite films via a low-cost, eco-friendly, low-temperature, and in-situ polymerization synthesis, which obtain novel flexible and conductive polylacticacid-cellulose nanofibril-graphene/polypyrrole (PLA–CNF–GR/PPy) composite films. The CNF was embedded in the PLA matrix to enhance the mechanical properties. Remarkably, when a few GR (1%) powder was added, the tensile strength of composite films increased by 5.6%, respectively, compared with pure PLA–CNF, and increased by 17.6% compared with the PLA. The GR and CNF had a positive influence on mechanical properties of composite films. In addition, the PLA–CNF–GR/PPy composite films exhibited many unique properties when GR powder was introduced, including high thermal stability, and especially electrical conductivity. The electrical conductivity of the PLA–CNF–GR/PPy composite films increased from 0.12 to 1.06 S/cm as the content of GR powder increased from 0 to 10%. The PLA–CNF–GR-10/PPy also demonstrated excellent flexible stability, only 7.5% deviation after over 100 bending cycles. Furthermore, we designed and found that the exploration of a flexible solid-state supercapacitor assembled with PLA–CNF–GR-10/PPy composite electrodes had a capacitance of 30 F/g at a current density of 0.5 A/g. Although it was not quite as prominent as the capacitance, it provided an innovative means for preparing the conductive composite films. Based on these advantages the PLA–CNF–GR/PPy could be considered as sensors, flexible electrodes, and flexible displays. It also opens a new field of potential applications of biodegradable materials.

Effect of freezing on electrical properties and quality of thawed chicken breast meat

Ran Wei,Peng Wang,Minyi Han,Tianhao Chen,Xinglian Xu,Guanghong Zhou 아세아·태평양축산학회 2017 Animal Bioscience Vol.30 No.4

Objective: The objective of this research was to study the electrical properties and quality of frozen-thawed chicken breast meat and to investigate the relationship between these parameters at different times of frozen storage. Methods: Thawed samples of chicken breast muscles were evaluated after being kept in frozen storage at –18°C for different periods of time (1, 2, 3, 4, 5, 6, 7, and 8 months). Results: The results showed that water-holding capacity (WHC) and protein solubility decreased while thiobarbituric acid-reactive substances content increased with increasing storage time. The impedance module of samples decreased during 8-month frozen storage. Pearson correlation coefficients showed that the impedance change ratio (Q value) was significantly (p<0.05) related to pH, color, WHC, lipid oxidation and protein solubility, indicating a good relationship between the electrical properties and qualities of frozen-thawed chicken breast meat. Conclusion: Impedance measurement has a potential to assess the quality of frozen chicken meat combining with quality indices.

Dynamic Multi-objective Construction Site Layout Planning Based on BIM

Guowu Tao,Haibo Feng,Jingchun Feng,Tianhao Wang 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.4

The planning effectiveness of construction site layout greatly influences construction efficiency. Many previous studies assumed that all the facilities exist on the construction sites for the whole duration of the projects. Some researchers found the shortcomings and developed models to improve it. But these models also have different limitations, such as ignoring the future impact of the layout decision in early construction phases on the later layout quality, only considering transportation costs when optimize the layouts, etc. To address these issues, this study proposes a building information modeling (BIM)-based model that dynamically optimizes the multi-objective construction site layout. In this model, BIM and construction schedules provide the updated construction project information. This model introduces the construction phase impact on layout. The layout of each construction phase is optimized in order of corresponding phase impact. Considering the sustainable development for construction industry, the noise pollution level is chosen to be the optimization objective together with the total transportation cost. In order to balance the noise pollution level and total transportation cost, the multi-objective particle swarm optimization (MOPSO) is applied to obtain trade-off solutions. A case study is presented to demonstrate the capability of the proposed model. The results indicate that the proposed dynamic construction site layout plan (CSLP) reduces transportation cost by 43.45% and 11.46% compared with the original and static construction site layout. This study breaks the traditional site layout plan order and locates the facilities in order of their phase impact, which can greatly reduce the transportation cost on the site. It also incorporates the noise pollution reduction into CSLP to enhance on-site sustainability.

Adaptive virtual impedance control based on second-order generalized integral for circulating current suppression

Zhang, Baifu,Han, Xiaoqing,Meng, Runquan,Ren, Chunguang,Wang, Lei,Song, Tianhao,Liu, Yizhao The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

The redundant design of multi-paralleled bidirectional power converters (BPCs) provides technical support for hybrid microgrid systems to consume more distributed generations (DGs) and DC loads. However, the multi-BPCs also provide paths for circulating current. In addition, the AC sub-grid may operate under unbalanced conditions due to the consumption of single-phase loads and power electronic devices. In addition, unbalanced three-phase voltage deteriorates the generation of circulating current. In this paper, an adaptive virtual impedance control method based on second-order generalized integration (SOGI) is proposed to suppress circulating current on the basic analysis of circulating current generation mechanism, the equivalent model establishment, and the suppression principle. The virtual impedance is dynamically adjusted in real-time based on the power oscillation caused by unbalanced voltage. Moreover, an integral term is added to the reactive power droop control to realize the tracking of voltage without static error. Finally, the effectiveness and feasibility of the proposed control algorithm are verified by experiments. The research results show that the proposed control method can optimize the damping characteristics, reduce the voltage difference between the BPCs, and improve the current sharing effect.

Model predictive current control of asymmetrical hybrid cascaded multilevel inverter

Jingang Han,Pinxuan Zhao,Gang Yao,Hao Chen,Yide Wang,Mohamed Benbouzid,Tianhao Tang 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.4

Asymmetrical hybrid cascaded (AHC) multilevel inverters (MLIs) adapt in medium- and high-power applications due to their good output voltage performance and numerous voltage levels. Research on reliable control schemes for AHC MLIs is necessary due to complicated practical conditions. This study presents a finite control set–model predictive control (FCSMPC) algorithm for a three-phase AHC MLI. The topology has few switching component requirements and generates many voltage levels through changes in the DC power supply ratio. FCS-MPC is designed for AHC MLIs to achieve stable and reliable control. Delay compensation and computational burden relief are also realized. Simulation and experiment results confirm the good performance of the proposed algorithm for AHC MLIs under steady-state and dynamic processes.