Novel frictional algorithm implementing angular increment for two-dimensional frictional systems

Deng Zhao,Shijing Wu,Qiaoquan Li,Xiaofeng Li,Xiaoyong Li,Xiaosun Wang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7

This study proposes a new frictional algorithm that implements angular increment. The proposed algorithm is used to solve the numerical solutions of dynamic problems in two-dimensional frictional systems. It can accurately obtain the motion responses of a lumped mass under time-varying external forces, and it can compensate for the shortcomings of the numerical frictional algorithm that implements a time step. Specifically, the proposed algorithm 1) overcomes the difficulties encountered when the angles between resultant tangential forces and slip motion are infinitely close, 2) provides accurate solutions for two-dimensional systems under fierce planar motions, and 3) calculates the responses of the mass within a reasonable period. We compare the computation accuracy, efficiency, and robustness of the proposed frictional algorithm and the previous frictional algorithm [1] through several representative scenarios. We reveal that the proposed algorithm has superior computation accuracy, efficiency, and robustness for two-dimensional frictional problems involving slip/stick transitions and sharp bending.

Improving Dielectric Properties in Novel P(VDF‑HFP)/V2AlC MAX/Montmorillonite Composite Films via Interfacial Electric‑Leakage Depressing Strategy

Xiaofeng Xia,Junquan Zhou,Huimin Ding,Qin Li,Maolin Bo,Qihuang Deng,Yefeng Feng 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.1

Dielectric constants of polymer/conductor composites are often high, owing to strong interface interaction in those composites. They can be used for dielectric energy storage, but they usually have high dielectric loss and conductivity. In order toreduce the dielectric loss and conductivity in poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP))/V2AlC MAXcomposites, in this study, we explored the novel P(VDF-HFP)/V2AlC MAX/montmorillonite (MMT) ternary composites. Compared with binary composites, the ternary composites showed the mildly reduced dielectric constant, significantlydecreased dielectric loss and conductivity. Using highly-conductive V2AlCMAX filler aimed at taking advantage of thepolymer/MAX interface polarization to increase the dielectric response of composites. Employing well-insulating MMTfiller aimed at reducing the interface electric leakage conduction. At 1 kHz, the outstanding ternary composite with 2 wt%MMT and 20 wt% MAX could exhibit a high dielectric constant of ca. 27 and low dielectric loss of ca. 0.21. This workmight offer a new research idea for the construction of high-performance composite dielectric films containing modernMAX ceramic fillers.

MiR-126-3p inhibits apoptosis and promotes proliferation by targeting phosphatidylinositol 3-kinase regulatory subunit 2 in porcine ovarian granulosa cells

Zhou, Xiaofeng,He, Yingting,Jiang, Yao,He, Bo,Deng, Xi,Zhang, Zhe,Yuan, Xiaolong,Li, Jiaqi Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.6

Objective: Numerous studies have indicated that the apoptosis and proliferation of granulosa cells (GCs) are closely related to the normal growth and development of follicles and ovaries. Previous evidence has suggested that miR-126-3p might get involved in the apoptosis and proliferation of GCs, and phosphatidylinositol 3-kinase regulatory subunit 2 (PIK3R2) gene has been predicted as one target of miR-126-3p. However, the molecular regulation of miR-126-3p on PIK3R2 and the effects of PIK3R2 on porcine GCs apoptosis and proliferation remain virtually unexplored. Methods: In this study, using porcine GCs as a cellular model, luciferase report assay, mutation and deletion were applied to verify the targeting relationship between miR-126-3p and PIK3R2. Annexin-V/PI staining and 5-ethynyl-2'-deoxyuridine assay were applied to explore the effect of PIK3R2 on GCs apoptosis and proliferation, respectively. Real-time quantitative polymerase chain reaction and Western Blot were applied to explore the regulation of miR-126-3p on PIK3R2 expression. Results: We found that miR-126-3p targeted at PIK3R2 and inhibited its mRNA and protein expression. Knockdown of PIK3R2 significantly inhibited the apoptosis and promoted the proliferation of porcine GCs, and significantly down-regulated the mRNA expression of several key genes of PI3K pathway such as insulin-like growth factor 1 receptor (IGF1R), insulin receptor (INSR), pyruvate dehydrogenase kinase 1 (PDK1), and serine/threonine kinase 1 (AKT1). Conclusion: MiR-126-3p might target and inhibit the mRNA and protein expressions of PIK3R2, thereby inhibiting GC apoptosis and promoting GC proliferation by down-regulating several key genes of the PI3K pathway, IGF1R, INSR, PDK1, and AKT1. These findings would provide great insight into further exploring the molecular regulation of miR-126-3p and PIK3R2 on the functions of GCs during the folliculogenesis in female mammals.

The Investigation of Function of Mineral Mud for the Skin

Yijie Du,Xiaofeng Deng,Li Li,Yinmao Dong 한국피부과학연구원 2016 아시안뷰티화장품학술지 Vol.14 No.1

목적: 본 연구는 미네랄머드가 류머티스성 질환, 건선 등 질병에 민간적 응용과 임상적 응용으로 많이 사용됨에 따 라 미네랄머드의 피부 임상응용을 목적으로 연구를 진행하였다. 방법: 미네랄머드의 소염, 항산화 작용을 요약하고, 미네랄머드를 화장품에 응용함에 있어서 존재하는 문제를 발 견하고 화장품영역에서의 발전방향을 제시하였다. 결과: 류머티스성 질환, 건선 등 난치 성 피부병의 치료는 미네랄머드의 소염, 항산화작용에 의한 것으로 보인다. 결론: 미네랄머드가 화장품 소재로서의 희망적인 가능성을 가지고 있지만 화장품 완제품으로 개발하기 위해서는 아직도 해결해야 할 여러 문제점들이 있다고 사료된다. Purpose: The treatment of mineral mud in rheumatic disease, psoriasis and other disease has been widely recognized in clinic application. We aim to explore the effect of mineral mud on the skin through it clinic application. Methods: We summarize the function of mineral mud in anti-inflammation, anti-oxidation, et al and point out the existing in the application of mineral mud in cosmetics and its development status. Results: Mineral mud have positive effects on rheumatic diseases through its properties of anti-inflammatory and anti-oxidation. Conclusion: The results demonstrate that mineral mud had a good prospect in cosmetics, but there are still many problems to be solved.

Impedance Interaction Modeling and Analysis for Bidirectional Cascaded Converters

Yanjun Tian,Fujin Deng,Zhe Chen,Xiaofeng Sun,Yanting Hu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

For the cascaded converter system, the output impedance of source converter interacts with the input impedance of load converter, and the interaction may cause the system instability. In bidirectional applications, when the power flow is reversed, the impedance interaction also varies, which brings more uncertainty to the system stability. An investigation is performed here for showing that the forward and reverse interactions are prominently different in terms of dynamics and stability even though the cascaded converter control remains unchanged. An important guideline has been drawn for the control of the cascaded converter. That is when voltage mode converter working as the load converter; the constant power mode converter as the source converter, the system is more stable. The concluded findings have been verified by simulation and experimental results.

Impedance Coordinative Control for Cascaded Converter in Bidirectional Application

Yanjun Tian,Fujin Deng,Zhe Chen,Xiaofeng Sun,Yanting Hu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Two stage cascaded converters are widely used in bidirectional applications, but the negative impedance may cause system instability. Actually the impedance interaction is much different between forward power flow and reversed power flow, which will introduce more uncertainty to the system stability. This paper proposes a control method for the constant power controlled converter in cascaded system, and consequently it can change the negative impedance of constant power converter into resistive impedance, which will improve the cascaded system stability, as well as merge the impedance difference between forward and reversed power flow. This paper addresses the analysis with the topology of cascaded dualactive - bridge converter (DAB) with inverter, and the proposed control method can also be implemented in unidirectional applications and other general cascaded converter system. The effectiveness has been validated by both simulation and experimental results.

Realizing Rationally-Balanced Dielectric Properties in Fluoropolymer/Cr2AlC MAX Composites Modified by 2D-BN

Qin Li,Junquan Zhou,Yanhui Chen,Xiaofeng Xia,Maolin Bo,Qihuang Deng,Yefeng Feng 한국고분자학회 2020 Macromolecular Research Vol.28 No.13

Polymer/conductor composite dielectric materials have a high dielectric constant. In recent years, composite dielectrics have become a study hotspot in highdensity energy storage capacitors. However, high dielectric loss and high electrical conductivity make the application of the composite materials very limited. In order to obtain composite materials with high dielectric constant, low dielectric loss and low conductivity, we added the insulating boron nitride (BN) filler into polymer/Cr2AlC composites. As a conductive filler, Cr2AlC ternary-layered-compound (MAX) ceramic has an interface polarization with the polymer matrix, thereby increasing the dielectric constant of the composites. The insulating BN has a very low electrical conductivity, which can effectively reduce the electrical conductivity and dielectric loss of the composites. Compared with the binary polymer/Cr2AlC composite materials, the ternary polymer/Cr2AlC/BN composite materials can achieve the low dielectric loss and low conductivity as well as properly-lowered dielectric constant. The ternary composite material filled with 10 wt% Cr2AlC and 2 wt% BN has a dielectric constant of about 30, a dielectric loss of about 0.7 and a conductivity of about 4.6×10- 7 S m-1 at 100 Hz. In this work, high-performance composite dielectrics were prepared through good cooperation between conductive and insulating ceramic fillers, which might provide an idea for design of promising energy storage capacitors.