Type synthesis of 3T2R decoupled hybrid mechanisms with large bearing capacity

Sen Wang,Shihua Li,Haoran Li,Yajie Zhou,Yongjie Wang,Xinyu Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

This paper proposes a new synthesis method of three translational and two rotational (3T2R) decoupled hybrid mechanism with large bearing capacity, based on the screw theory and the atlas method. According to the degree of freedom and decoupled characteristics of the 3T and 2R mechanisms, the decoupled conditions for the 3T and 2R parallel mechanisms are proposed. The optimal conditions for the motion/force transmission performance of the 3T decoupled parallel mechanisms with redundant actuation is presented. A redundant actuated limb construction method is proposed to improve the load capacity of the hybrid mechanism. Following the design steps of the fully decoupled hybrid mechanism, 3T2R hybrid mechanisms with large load capacity are obtained. Kinematics and statics analysis verify the correctness of the proposed synthesis method. The mechanism synthesized by this method has a good application prospect in large load occasion.

Partial Discharge Detection Method Based on DD-DT CWT and Singular Value Decomposition

Wu Chao,Gao Yiran,Wang Ruoyan,Wang Kai,Liu Siyang,Nie Yongjie,Wang Ping 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4

Partial discharge (PD) detection is signifi cant for insulation condition evaluation of electrical equipment. However, it often happens that the PD signals are submerged by interferences, which will cause the inaccurate detection results. In this paper, we propose a PD detection method based on double-density dual-tree complex wavelet transform (DD-DT CWT) and singular value decomposition (SVD) to solve this problem. The denoising method based on DD-DT CWT has better performance in both removing interferences and retaining features of PD signals. The inner product of the singular value matrix obtained by applying SVD to denoised high-frequency wavelet coeffi cient matrix can concisely represent the complexity of the tested signal, which can be used as a basis to judge the existence of the PD signal. Besides, Otsu algorithm is introduced to calculate the threshold to locate the appearance time of the PD signal. Experimental results show that the proposed method can detect the PD signal with the accuracy rate of 77.8% when PD signals are submerged by noises, while the traditional method cannot detect the existence of the PD signal. In addition, only the method proposed in this paper can detect the appearance time of the PD signal with the accuracy rate of 97.2%.

Separation of valuable metals from mixed cathode materials of spent lithium-ion batteries by single-stage extraction

Yongjie Li,Qiang Fu,Hongyun Qin,Kun Yang,Junnan Lv,Qicheng Zhang,Zhang Hui,Feng Liu,Xia Chen,Ming Wang 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.10

With the intensity of resource scarcities and environmental problems, the disposal and recovery of spent lithium-ion batteries, especially recovery of valuable metals, becomes vital. In this work, a method of co-extracting nickel, cobalt, manganese and being separated from lithium by single-stage solvent extraction is proposed. The extraction and separation process of D2EHPA was studied. The effects of extractant concentration, saponification percentage, extraction time and O:A on the extraction efficiency of D2EHPA were systematically studied. Nearly 100% manganese, 94% cobalt and about 90% nickel were co-extracted and separated from lithium using D2EHPA in kerosene by single-stage extraction. The maximum value of separation factors (Ni/Li, Co/Li and Mn/Li) was 13.03, 23.42 and 1904.24. The mathematical model of extraction of four ions was developed by combination of Levenberg-Marquardt method and Universal Global Optimization method. The proposed extraction model accurately fits the experimental data and helps to predict the extraction efficiency of each metal under the corresponding conditions.

The multifunctional RNA-binding protein hnRNPK is critical for the proliferation and differentiation of myoblasts

( Yongjie Xu ),( Rui Li ),( Kaili Zhang ),( Wei Wu ),( Suying Wang ),( Pengpeng Zhang ),( Haixia Xu ) 생화학분자생물학회(구 한국생화학분자생물학회) 2018 BMB Reports Vol.51 No.7

HnRNPK is a multifunctional protein that participates in chromatin remodeling, transcription, RNA splicing, mRNA stability and translation. Here, we uncovered the function of hnRNPK in regulating the proliferation and differentiation of myoblasts. hnRNPK was mutated in the C2C12 myoblast cell line using the CRISPR/Cas9 system. A decreased proliferation rate was observed in hnRNPK-mutated cells, suggesting an impaired proliferation phenotype. Furthermore, increased G2/M phase, decreased S phase and increased sub-G1 phase cells were detected in the hnRNPK-mutated cell lines. The expression analysis of key cell cycle regulators indicated mRNA of Cyclin A2 was significantly increased in the mutant myoblasts compared to the control cells, while Cyclin B1, Cdc25b and Cdc25c were decreased sharply. In addition to the myoblast proliferation defect, the mutant cells exhibited defect in myotube formation. The myotube formation marker, myosin heavy chain (MHC), was decreased sharply in hnRNPK-mutated cells compared to control myoblasts during differentiation. The deficiency in hnRNPK also resulted in the repression of Myog expression, a key myogenic regulator during differentiation. Together, our data demonstrate that hnRNPK is required for myoblast proliferation and differentiation and may be an essential regulator of myoblast function. [BMB Reports 2018; 51(7): 350-355]

Upregulation of miR-223 in the rat liver inhibits proliferation of hepatocytes under simulated microgravity

Yongjie Chen,Ji Xu,Chao Yang,Hongyu Zhang,Feng Wu,Jian Chen,Kai Li,Hailong Wang,Yu Li,Yinghui Li,Zhongquan Dai 생화학분자생물학회 2017 Experimental and molecular medicine Vol.49 No.-

Long-term spaceflight affects numerous organ systems in the body, including metabolic dysfunction. Recently, ample evidence has demonstrated that the liver is a vulnerable organ during spaceflight. However, the changes in hepatocyte proliferation and cell cycle control under microgravity remain largely unexplored. In the present study, we first confirmed that the serum levels of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase, biochemical markers of liver function, were altered in rats under tail suspension (TS) conditions to simulate microgravity, as shown in previous reports. Next, we demonstrated that the cell proliferation activity, determined by Ki67, PCNA and PH3, was significantly decreased at the different TS time points (TS for 14, 28 and 42 days) compared with that in the control group. Consistently, the positive cell cycle regulators Ccna2, Ccnd1, Cdk1, Cdk2 and cyclin D3 were also significantly decreased in the TS groups as shown by quantitative real-time PCR and western blotting analysis. Subsequent analysis revealed that the aberrant hepatocyte proliferation inhibition under simulated microgravity was associated with the upregulation of miR-223 in the liver. We further found that miR-223 inhibited the proliferation of Hepa1-6 cells and identified CDK2 and CUL1 as its direct targets. In addition, the decreased expression of CDK2 and CUL1 was negatively correlated with the level of p27 in vitro and in vivo, which may have been responsible for retarding hepatocyte proliferation. Collectively, these data indicate that upregulation of miR-223 was associated with the inhibition of liver cell growth and reveal the role of miR-223 in rat hepatocyte proliferation disorders and the pathophysiological process under simulated microgravity.

Very long life fatigue behaviors of 16Mn steel and welded joint

Yongjie Liu,Chao He,Chongxiang Huang,Muhammad K. Khan,Qingyuan Wang 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.5

Very long life fatigue tests were carried out on 16Mn steel base metal and its welded joint byusing the ultrasonic fatigue testing technique. Specimen shapes (round and plate) were considered for both the base metal and welded joint. The results show that the specimens present different S-N curve characteristics in the region of 105-109 cycles. The round specimens showed continuously decreasingtendency while plate specimens showed a steep decreasing step and an asymptotic horizontal one. The fatigue strength of round specimen was found higher than plate specimen. The fatigue strength of as-welded joint was 45.0% of the base material for butt joint and 40% for cruciform as-welded joint. It was found that fracture can still occur in butt joint beyond 5×106 cycles. The cruciform joint has a fatigue limit in the very long life fatigue regime (107-109 cycles). Fatigue strength of butt as-welded joint was much higher as compared to cruciform as-welded joint. Improvement in fatigue strength of welded joint was found due to UPT. The observation of fracture surface showed crack mainly initiated from welded toe at fusion areas or geometric discontinuity sites at the surface in butt joint and from welded toe in cruciform joint.

Intelligent Matching Assembly: System Design Based on Reuse of Ultra-Difference Parts

Yongjie Zhang,Kang Cao,Zhiqiang Cai,Xinwen Wang,Wei Jin 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.7

As the industrial digitalization has been recently leaping forward, high-efficiency production processes emerge, and assembly integration technologies are being progressively developed. For high-tech industries (e.g., aerospace manufacturing), however, unprecedented challenges are imposed on the conventional assembly manufacturing process technology. To be specific, the shallow digitizing and intelligent technologies fail to satisfy the rising requirements for efficiency, pass rates and cost; in particular, the way to down-regulate the unqualified rate and assembly cost of parts production remains unclear. In the present study, an intelligent matching assembly system was designed for reapplying out-of-tolerance parts. In addition, the concept of the mating base is proposed. Next, the fi t relation between parts is quantified by employing the functional expression of dimension data, and such a relation is characterized as a function constraint with a variable of dimension. Moreover, the designed intelligent matching system was introduced into the existing assembly process to reemploy a number of unqualified parts and determine the matching parts most suitable for the original unqualified parts. On that basis, the most suitable parts are enabled to be involved in the assembly activities, as an attempt to satisfy the design requirements. To efficiently find the optimal matching scheme in the database of the unqualified parts and most effectively employ the unqualified parts, a set of optimal matching algorithms are proposed, thereby significantly down-regulating the production cost. Lastly, Monte Carlo method was adopted to simulate the actual production data, and the optimal matching scheme determined by the intelligent matching system was analyzed and assessed, which verified the effectiveness and practicability of the system.

Very long life fatigue behaviors of 16Mn steel and welded joint

Liu, Yongjie,He, Chao,Huang, Chongxiang,Khan, Muhammad K.,Wang, Qingyuan Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.5

Very long life fatigue tests were carried out on 16Mn steel base metal and its welded joint by using the ultrasonic fatigue testing technique. Specimen shapes (round and plate) were considered for both the base metal and welded joint. The results show that the specimens present different S-N curve characteristics in the region of $10^5-10^9$ cycles. The round specimens showed continuously decreasing tendency while plate specimens showed a steep decreasing step and an asymptotic horizontal one. The fatigue strength of round specimen was found higher than plate specimen. The fatigue strength of as-welded joint was 45.0% of the base material for butt joint and 40% for cruciform as-welded joint. It was found that fracture can still occur in butt joint beyond $5{\times}10^6$ cycles. The cruciform joint has a fatigue limit in the very long life fatigue regime ($10^7-10^9$ cycles). Fatigue strength of butt as-welded joint was much higher as compared to cruciform as-welded joint. Improvement in fatigue strength of welded joint was found due to UPT. The observation of fracture surface showed crack mainly initiated from welded toe at fusion areas or geometric discontinuity sites at the surface in butt joint and from welded toe in cruciform joint.

Characteristics analysis of micro‑source half‑bridge converter series Y‑connection based microgrid systems

Xinggui Wang,Yingjie Ding,Jinjian Li,Yongji Guo 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.10

Due to the problems of serious circulation current, large switching loss, high harmonic content, unstable voltage, and high engineering cost in existing microgrid structures, a micro-source half-bridge converter series Y-connection-based microgrid (HCSY-MG) is proposed in this paper. On the basis of the equivalent circuit in the system islanding state, the output characteristics of the system and the corresponding influencing factors under both square wave modulation and phase-shifted pulse width modulation (PS-PWM) are analyzed. Under single-cycle square wave modulation, since the DC-side capacitors of some micro-source half-bridge converters are affected by reactive power, which can result in system output voltage fluctuations or even an in-phase imbalanced state, a multi-period cycle modulation strategy is applied to solve this problem. Under the PS-PWM strategy, if the modulation degree and capacitance of the micro-source half-bridge converters are reasonably set, the output voltage of the system can be guaranteed to be in an in-phase equilibrium state. A simulation model and an experimental platform are built to verify the feasibility of the system and the effectiveness of the proposed strategy.

Endophytes from Natural Festuca spp. in Southwest China and Their Compatibility with Tall Fescue Cultivars

Yaoyao Wang,Yongji Du,Liebao Han,Deying Li 한국잔디학회 2009 Weed & Turfgrass Science Vol.23 No.1

Investigating endophyte distribution, naturally occurring in native grasses, is important for understanding endophyte-grass associations and using the beneficial effects of endophytes in cultivated plants. The goal of this study was to investigate endophytes from natural Festuca spp. in Yunnan, Guizhou, and Sichuan Provinces of China, and to study the compatibility between the endophytes and turf type tall fescue (Festuca arundinacea) which is widely used for lawn and athletic fields in that region. Of 628 accessions in F. ovina, 421 had endophytes identified in leaf sheath from on-site microscopic examination. From Festuca spp, three isolates were obtained from the seeds and ninety isolates were obtained from seedlings established from the collected seeds. The isolates from F. ovina and F. stapfii were tentatively identified as Neotyphodium typhinum and Neotyphodiumstarii, respectively. We tested compatibility of the two fungal species with seven tall fescue cultivars, Little Hero, Sub Boy, Eldorado, Arid III, Millennium, Crossfire, and Fawn. N. typhinum or N. starii did not infect ‘Fawn’with either seed injection or seed soaking method. The highest infection rate byboth N. typhinum and N. starii was in ‘Sun Boy’ and ‘Eldorado’. There were significant interaction effects between tall fescue cultivar and type of endophyte on infection. Investigating endophyte distribution, naturally occurring in native grasses, is important for understanding endophyte-grass associations and using the beneficial effects of endophytes in cultivated plants. The goal of this study was to investigate endophytes from natural Festuca spp. in Yunnan, Guizhou, and Sichuan Provinces of China, and to study the compatibility between the endophytes and turf type tall fescue (Festuca arundinacea) which is widely used for lawn and athletic fields in that region. Of 628 accessions in F. ovina, 421 had endophytes identified in leaf sheath from on-site microscopic examination. From Festuca spp, three isolates were obtained from the seeds and ninety isolates were obtained from seedlings established from the collected seeds. The isolates from F. ovina and F. stapfii were tentatively identified as Neotyphodium typhinum and Neotyphodiumstarii, respectively. We tested compatibility of the two fungal species with seven tall fescue cultivars, Little Hero, Sub Boy, Eldorado, Arid III, Millennium, Crossfire, and Fawn. N. typhinum or N. starii did not infect ‘Fawn’with either seed injection or seed soaking method. The highest infection rate byboth N. typhinum and N. starii was in ‘Sun Boy’ and ‘Eldorado’. There were significant interaction effects between tall fescue cultivar and type of endophyte on infection.