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A Deep Investigation of the Thermal Decomposition Process of Supported Silver Catalysts
Jiang, Jun,Xu, Tianhao,Li, Yaping,Lei, Xiaodong,Zhang, Hui,Evans, D.G.,Sun, Xiaoming,Duan, Xue Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.6
A deep understanding of the metallic silver catalysts formation process on oxide support and the formation mechanism is of great scientific and practical meaning for exploring better catalyst preparing procedures. Herein the thermal decomposition process of supported silver catalyst with silver oxalate as the silver precursor in the presence of ethylenediamine and ethanolamine is carefully investigated by employing a variety of characterization techniques including thermal analysis, in situ diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation mechanism of supported silver particles was revealed. Results showed that formation of metallic silver begins at about $100^{\circ}C$ and activation process is essentially complete below $145^{\circ}C$. Formation of silver was accompanied by decomposition of oxalate group and removal of organic amines. Catalytic performance tests using the epoxidation of ethylene as a probe reaction showed that rapid activation (for 5 minutes) at a relatively low temperature ($170^{\circ}C$) afforded materials with optimum catalytic performance, since higher activation temperatures and/or longer activation times resulted in sintering of the silver particles.
Duan Suling,Jiang Shanlin,Dai Huan,Wang Luping,He Zhenan 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.3
Combinatorial optimization problems have very important applications in information technology, transportation, economics, management, network communication, and other fields. Since the problem size in real-scenario application is in large-scale, the demand for real-time and efficient solving approaches increases rapidly. The traditional exact methods guarantee the optimality of the final solution, but these methods can hardly solve the problem in acceptable time due to extremely high computational costs. Heuristic approaches can find feasible solutions in a limited time, while these approaches cannot meet the demand of solution quality. In recent years, hybrid algorithms based on exact methods and heuristic algorithms show outstanding performance in solving large-scale combinatorial optimization problems. The hybridization not only overcomes the shortcomings from single algorithm but also fully utilizes the search ability for population-based approaches as well as the interpretability in exact methods, which promotes the application of combinatorial optimization in real-world problems. This paper reviews existing studies on hybrid algorithms combining exact method and evolutionary computation, summarizes the characteristics of the existing algorithms, and directs the future research.
Duan Yafei,Tang Yapeng,Huang Jianhua,Zhang Jiasong,Lin Heizhao,Jiang Shigui,Wang Ruixuan,Wang Guofu 한국미생물학회 2020 The journal of microbiology Vol.58 No.9
Microbial communities greatly affect rearing water quality and the larvae health during shrimp hatchery periods. In this study, we investigated the microbial communities of rearing water and larvae of Litopenaeus vannamei after treating hatchery water with different kinds of chemical disinfectants: no disinfectants (Con), chlorine dioxide (ClO2), formaldehyde solution (HCHO), bleach powder (CaClO), and iodine (I2). The water and larval samples were collected from nauplius 6 (N6), zoea 1 (Z1), mysis 1 (M1), and postlarvae 1 (P1) shrimp growth periods. 16S rDNA high-throughput sequencing revealed that the bacterial composition of the rearing water was more complex than that of the larvae, and the bacterial community of the rearing water and the larvae fluctuated significantly at the P1 and Z1 periods, respectively. Disinfectants altered the bacterial diversity and composition of the rearing water and larvae. Specifically, in the rearing water of the P1 period, Proteobacteria abundance was increased in the HCHO group; while Bacteroidetes abundance was decreased in the ClO2, HCHO, and I2 groups but increased in the CaClO group. In the larvae of the Z1 period, Firmicutes (especially Bacillus class) abundance was increased in the CaClO group, but decreased in the ClO2, HCHO, and I2 groups. Network analyses revealed that the genera Donghicola, Roseibacterium, Candidatus-Cquiluna, and Nautella were enriched in the rearing water, while Halomonas, Vibrio, and Flavirhabdus had high abundance in the larvae. The survival of shrimp was influenced by disinfectants that were inconsistent with the bacterial community changes. These results will be helpful for using microbial characteristics to facilitate healthy shrimp nursery.
Duan, Wei,Wen, Miaowen,Jiang, Xueqin,Yan, Yier,Ho Lee, Moon SpringerOpen 2016 Eurasip Journal on Wireless Communications and Net Vol.2016 No.-
<P>In this paper, we investigate the robust relay beamforming design for a multi-input multi-output (MIMO) two-way relay networks (TWRN) by considering imperfect and reciprocal channel state informations (CSIs). In order to maximize the sum-rate (SR) subject to the individual relay power constraint, we first equivalently convert the objective problem into a sum of the inverse of the signal-to-residual-interference-plus-noise ratio (SI-SRINR) problem. The SI-SRINR problem can be reformulated as a biconvex semi-definite programming (SDP) which employs bounded channel uncertainties as the worst-case model. Then, we convert residual-interference-plus-noise (RIN) and relay power constraints into linear matrix inequalities (LMIs). By this way, the objective problem can be tackled by the proposed efficient iterative algorithm. The analysis demonstrates the procedures of the proposed SI-SRINR robust design.</P>
Enhanced beamforming design and sum-rate maximization for two-way multi-relay networks
Duan, Wei,Yan, Yier,Hai, Han,Jiang, Xueqin,Yu, Haiyang,Lee, Moon Ho SpringerOpen 2016 Eurasip Journal on Wireless Communications and Net Vol.2016 No.-
<P>In this paper, we investigate an enhanced relay beamforming design for two-way relay networks (TWRN). In order to reduce the computational complexity, we derive a sum of the inverse of the signal-to-noise ratio (SI-SNR) problem equivalent to the objective sum-rate (SR) problem. The SI-SNR problem can be reformulated as a simple optimization problem by using the Cholesky decomposition and Cauchy-Schwarz inequality, and solved by the interior-point method. The numerical results show that the proposed SI-SNR method can not only reduce the computational complexity but also have the same SR performance as that of the conventional works.</P>
Shougang Duan,Yufeng Yang,Yong Dong,Yu Wang,Beibei Jiang,Chuanqiang Li,Zhengrong Zhang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.6
Ultra-fine grain AlCrFe2Ni2Wx(x = 0.1, 0.2, 0.3, 0.4) alloys were designed and prepared by vacuum arc melting, and correspondingmicrostructural evolution and mechanical properties were investigated. All of the alloys show a mixed structurewith FCC + BCC (B2) + TCP phases. The addition of W element has a significant effect on the formation mechanism of themorphology, which promotes the transition from FCC phase to μ phase and inhibits the spinodal decomposition of BCCphase. With the increase of W content, more μ phase precipitates from the FCC phase and grain boundaries. After the dissolutionof W element into matrix, the formed oversaturated solid solution and precipitated μ phase have the effect of solidsolution strengthening and second phase strengthening, respectively. The yield strength and Vickers hardness increasesfrom 765 to 1319.6 MPa and HV 332.2 to HV 461.8, respectively. The addition of W element enhances the strength of thealloys but reduced ductility. The AlCrFe2Ni2W0.1alloy exhibits outstanding comprehensive mechanical properties, with itsfracture strength reaching 2726.5 MPa and a considerable compressive strain of 43.3%, which implies promising potentialengineering application.