Dislocation Density-Based Constitutive Model and Processing Map for T2 Copper During Isothermal and Time-Variant Deformation

Gang Chen,Yu Jin,Jing Wang,Cheng Zhang,Qiang Chen,Hongming Zhang,Xingjian Zhao,Zhiyong Li,Changhai Xie,Zhiming Du 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9

Isothermal compression tests were carried out to study the hot deformation behavior of T2 copper under various conditions. The deformation parameters, such as temperature and strain rate, have strong influence on flow stress and microstructureevolution of the alloy. A unified dislocation density-based model considering dynamic recovery and recrystallization wasestablished. And material parameters of the developed model were optimized by genetic algorithm. Comparisons betweenthe experimental and model data demonstrates that the developed model can precisely describe the flow behavior at quitewide range of deformation conditions. Meanwhile, the designed iterative procedure allows the model to be applied in timevariantdeformation conditions. Processing map and microstructure examination were constructed to optimize the processingwindow of the studied alloy. According to the processing maps, flow instability mainly appeared at low temperatures of500–650 °C and strain rates higher than 0.1 s−1. The optimum deformation parameters of T2 copper was concluded as thetemperature range of 700–800 °C and the strain rate of 0.1–1 s−1.

Minimum Distance based Precoder Design for General MIMO Systems using Gram Matrix

Zhiyong Chen,Xiaodong Xu 한국통신학회 2015 Journal of communications and networks Vol.17 No.6

Assuming perfect channel state information (CSI) atthe transmitter and receiver, the optimization problem of maximizingthe minimum Euclidean distance between two received signalsby a linear precoder is considered for multiple-inputmultipleoutput(MIMO) systems with arbitrary dimensions and arbitraryaryquadrature amplitude modulation (QAM) input. A generalprecoding framework is first presented based on the Gram matrix,which is shown for 2-dimensional (2-D) and 3-dimensional (3-D) MIMO systems when employing the ellipse expanding method(EEM). An extended precoder for high-dimensional MIMO systemis proposed following the precoding framework, where theGram matrix for high-dimensional precoding matrix can be generatedthrough those chosen from 2-D and 3-D results in associationwith a permutation matrix. A complexity-reduced maximumlikelihood detector is also obtained according to the special structureof the proposed precoder. The analytical and numerical resultsindicate that the proposed precoder outperforms the other precodingschemes in terms of both minimum distance and bit error rate(BER).

Polyetheretherketone implants with hierarchical porous structure for boosted osseointegration

Zhiyong Chen,Yu Chen,Yang Wang,JiaJia Deng,Xin Wang,Qingqing Wang,Yuehua Liu,Jiandong Ding,Lin Yu 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Background Good osseointegration is the key to the long-term stability of bone implants. Thermoplastic polyetheretherketone (PEEK) has been widely used in orthopedics; however, its inherent biological inertia causes fibrous tissue to wrap its surface, which leads to poor osseointegration and thus greatly limits its clinical applications. Methods Herein, we developed a facile yet effective surface modification strategy. A commonly used sulfonation coupled with “cold pressing” treatment in the presence of porogenic agent formed a three-dimensional hierarchical porous structure on PEEK surface. Subsequently, the effects of porous surface on the in vitro adhesion, proliferation and differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) were evaluated. Finally, the osteoinduction and osseointegration of surface-porous PEEK implant were examined in the rat distal femoral defect model. Results In vitro results showed that the surface modification did not significantly affect the mechanical performance and cytocompatibility of PEEK substance, and the porous structure on the modified PEEK substrate provided space for cellular ingrowth and enhanced osteogenic differentiation and mineralization of BMSCs. In vivo tests demonstrated that the surface-porous PEEK implant could effectively promote new bone formation and had higher bone-implant contact rate, thereby achieving good bone integration with the surrounding host bone. In addition, this modification technique was also successfully demonstrated on a medical PEEK interbody fusion cage. Conclusion The present study indicates that topological morphology plays a pivotal role in determining implant osseointegration and this facile and effective modification strategy developed by us is expected to achieve practical applications quickly.

Preparation, Characterization and Luminescence Properties of a Novel 1,10-Phenanthroline-Functionalized Polyimide and Its Europium(III) Complexes

Zhiyong Chen,Jianjun Lu,Xuping Li,Xuting Jin,Lijuan Shi,Miaoqing Liu,Zhilin Sun 한국고분자학회 2015 Macromolecular Research Vol.23 No.9

A novel 1,10-phenanthroline-functionalized polyimide (CMPI-Phen) was prepared as polymer matrix by the nucleophilic substitution reaction between chloromethylated polyimide (CMPI) and 5-amino-1,10-phenanthroline (NH2-Phen). Then, two kinds of luminescent materials of 1,10-phenanthroline-functionalized polyimide containing Eu(III) complexes, were obtained by two different methods. Their structures and properties were characterized by Fourier transform infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, inductively coupled plasma (ICP), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), luminescence spectrometry, and luminescence decay analysis. Investigations revealed that both the CMPI-Phen-Eu(III) and CMPI-Phen-Eu(TTA)3 display highly efficient red emissions, suggesting their potential application as luminescent materials. However, compared with CMPI-Phen-Eu(III), CMPI-Phen-Eu(TTA)3, where TTA stands for thenoyltrifluoroacetone, exhibits more excellent and stable fluorescence intensity and longer luminescence lifetime (134.30 μs). The weight-average molecular weights of CMPI-Phen-Eu(III) and CMPI-Phen- Eu(TTA)3 are 2.40×104 and 3.11×104, respectively. The Eu contents of CMPI-Phen-Eu(TTA)3 and CMPI-Phen-Eu(III) were measured by ICP to be 7.00% and 5.92%, respectively. TGA demonstrated that both CMPI-Phen-Eu(III) and CMPI-Phen-Eu(TTA)3 have high thermal stability and their 5% loss weight temperatures were 356 and 280 oC, respectively. Moreover, both CMPI-Phen-Eu(III) and CMPI-Phen-Eu(TTA)3 were soluble in polar solvents such as dimethylformamide (DMF), dimethylacetamide (DMAc), 1-methyl-2-pyrrolidone (NMP), and dimethylsulfoxide (DMSO) under heating conditions, and could be easily cast into tough thin films.

Optimal Allocation Method of Hybrid Active Power Filters in Active Distribution Networks Based on Differential Evolution Algorithm

Chen, Yougen,Chen, Weiwei,Yang, Renli,Li, Zhiyong The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

In this paper, an optimal allocation method of a hybrid active power filter in an active distribution network is designed based on the differential evolution algorithm to resolve the harmonic generation problem when a distributed generation system is connected to the grid. A distributed generation system model in the calculation of power flow is established. An improved back/forward sweep algorithm and a decoupling algorithm are proposed for fundamental power flow and harmonic power flow. On this basis, a multi-objective optimization allocation model of the location and capacity of a hybrid filter in an active distribution network is built, and an optimal allocation scheme of the hybrid active power filter based on the differential evolution algorithm is proposed. To verify the effect of the harmonic suppression of the designed scheme, simulation analysis in an IEEE-33 nodes model and an experimental analysis on a test platform of a microgrid are adopted.

Optimal Allocation Method of Hybrid Active Power Filters in Active Distribution Networks Based on Differential Evolution Algorithm

Yougen Chen,Weiwei Chen,Renli Yang,Zhiyong Li 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

In this paper, an optimal allocation method of a hybrid active power filter in an active distribution network is designed based on the differential evolution algorithm to resolve the harmonic generation problem when a distributed generation system is connected to the grid. A distributed generation system model in the calculation of power flow is established. An improved back/ forward sweep algorithm and a decoupling algorithm are proposed for fundamental power flow and harmonic power flow. On this basis, a multi-objective optimization allocation model of the location and capacity of a hybrid filter in an active distribution network is built, and an optimal allocation scheme of the hybrid active power filter based on the differential evolution algorithm is proposed. To verify the effect of the harmonic suppression of the designed scheme, simulation analysis in an IEEE-33 nodes model and an experimental analysis on a test platform of a microgrid are adopted.

Common edible insects and their utilization in China

Xiaoming CHEN,Ying FENG,Zhiyong CHEN 한국곤충학회 2009 Entomological Research Vol.39 No.5

This paper reviews the common edible insects and their use in China. One-hundred and seventy-eight insect species from 96 genera, 53 families and 11 orders are commonly eaten in China. Preparation of edible insects includes frying, braising, stewing, stewing after frying, boiling and roasting. The insect forms eaten range from eggs to adults; however, in restaurants most are larvae and pupae. More than 50 species have been analyzed for their nutritive elements and nutritional value and these data are reviewed here. Insect health foods sold in the Chinese market are also briefly discussed.

On the mechanism of vertical stabilizer plates for improving aerodynamic stability of bridges

Chen, Airong,Zhou, Zhiyong,Xiang, Haifan Techno-Press 2006 Wind and Structures, An International Journal (WAS Vol.9 No.1

Vertical stabilizer plates have been found to be an effective aerodynamic measure to improve the aerodynamic stability of bridges either with an open cross section or with a streamlined box cross section in wind tunnel testings and have been adopted in some long span bridges. By taking an open deck II-shaped section and a closed box section as examples, the mechanism of vertical stabilizer plates for improving aerodynamic stability are investigated by using numerical simulation based on Random Vortex Method. It is found that vertical stabilizer plates can increase the amplitude of the heaving motion, and decrease that of the rotational motion of the bridge decks.

Antidiabetic Effect of Flavones from Cirsium japonicum DC in Diabetic Rats

Zhiyong Liao,Xiaoli Chen,Mingjiang Wu 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.3

Cirsium japonicum DC is a traditional Chinese herb used along with other herbs to treat hypertension, traumatic hemorrhage, inflammation, and renal cellular injury. Here, we isolated two flavones from Cirsium japonicum DC, pectolinarin and 5,7-dihydroxy-6,4’-dimethoxy flavone (DDMF), and investigated their antidiabetic effect in diabetic rats established by intravenous injection with streptozotocin followed by feeding with high-carbohydrate/high-fat diet. Both pectolinarin and DDMF showed antidiabetic effect in diabetic rats. However, FECJ, a mixture of pectolinarin and DDMF, is more effective than pectolinarin and DDMF in improving the plasma glucose, cholesterol and triglycerides levels in diabetic rats. The altered activities of glucose metabolism-related enzymes in diabetic rats were well reversed after flavone treatment. The plasma adiponectin level was greatly increased in diabetic rats treated with FECJ, while no obvious effect of the flavones on the dysregulated plasma insulin level and expressions of leptin and glucose transporter 4 (GLUT4) was observed. Our data indicated that the flavones improved adiponectin expression, accompanied by restoring of the dysregulated activities of the glucose metabolism-related enzymes, ultimately resulting in well improved glucose and lipid homeostasis. Thus, an antidiabetic effect of Cirsium japonicum DC was revealed in diabetic rats, suggesting the potential benefit of the Cirsium japonicum DC as an alternative in treating diabetes mellitus.

Three birds with one stone: Nitrilotriacetic acid interface anchoring helps prepare efficient and stable perovskite solar cells

Chen Ting,Liu Pengfei,Liu Tianxiao,Li Xueyuan,Wang Huihui,He Tingwei,Liu Zhiyong 한국물리학회 2024 Current Applied Physics Vol.58 No.-

Electron transport layer (ETL) plays an important role in perovskite solar cells (PSCs). In this paper, a stable and cheap metal chelating agent, subnitrotriacetic acid (NTA), was used to modify SnO2 ETL in two ways:1) By incorporating NTA into SnO2 colloidal dispersion, the oxygen vacancy causing charge recombination was greatly reduced, and the recombination of psc was reduced by reducing the introduction of surface Ovs, 2) Spin-coating NTA at the SnO2/perovskite interface not only manages a large number of oxygen vacancies generated by high-temperature annealing, but also interacts with the unpaired Pb2+ in the perovskite absorption layer by interface modification of the C=O bond in NTA, passivates the surface of the perovskite layer, inhibits ion migration, stabilize the perovskite structure, and avoid its collapse, while significantly reducing the defect state density. By inhibiting the shallow interface trap and reducing the non-radiative recombination, efficient and stable perovskite solar cells were prepared. Under the condition of relative humidity greater than 40 % (RH), the efficiency of perovskite solar cells prepared by interface-anchored NTA was increased to 22.6 %, and the stability was significantly enhanced.