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, Volume 17 Issue 2 Previous Issue    Next Issue
Articles
Pressure drop in a packed bed with sintered ore particles as applied to sinter coolers with a novel vertically arranged design for waste heat recovery
Fu-you Tian, Lian-feng Huang, Li-wu Fan, Hong-liang Qian, Jia-xi Gu, Zi-tao Yu, Ya-cai Hu, Jian Ge, Ke-fa Cen
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2016, 17(2): 89-100.   https://doi.org/10.1631/jzus.A1500088
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The pressure drop over a packed bed with sintered ore particles was studied experimentally. The sintered ore particles were characterized to determine their equivalent particle diameter, bed voidage, and sphericity. The pressure drop experiments were performed on unsorted and sieved particles with various size distributions for a superficial velocity up to 2.4 m/s, covering flow regimes from laminar to turbulent. It was shown that the Ergun equation underestimates the pressure drop for such highly irregular-shaped particles by about 40%. The measured modified friction factor was well correlated to a scaled Ergun equation, which was verified to be valid for the modified particle Reynolds number up to 12 000 toward design and optimization of vertically arranged sinter coolers for waste heat recovery.
A hybrid short-term load forecasting method based on improved ensemble empirical mode decomposition and back propagation neural network
Yun-luo Yu, Wei Li, De-ren Sheng, Jian-hong Chen
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2016, 17(2): 101-114.   https://doi.org/10.1631/jzus.A1500156
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Short-term load forecasting (STLF) plays a very important role in improving the economy and security of electricity system operations. In this paper, a hybrid STLF method is proposed based on the improved ensemble empirical mode decomposition (IEEMD) and back propagation neural network (BPNN). To alleviate the mode mixing and end-effect problems in traditional empirical mode decomposition (EMD), an IEEMD is presented based on the degree of wave similarity. By applying the IEEMD method, the nonlinear and nonstationary original load series is decomposed into a finite number of stationary intrinsic mode functions (IMFs) and a residual. Among these components, the high frequency (namely IMF1) is always so small that it has little contribution to model fitting, while it sometimes has a great disturbance for the STLF. Therefore, the IMF1 is removed in the proposed hybrid method for denoising. The remaining IMFs and residual are forecast by BPNN, and then the forecasting results of each component are combined with BPNN to obtain the final predicted load series. Three groups of studies were done to evaluate the effectiveness of the proposed hybrid method. The results show that the proposed hybrid method outperforms other methods both mentioned in this paper and previous studies in terms of all the three standard statistical indicators considered in this study.
A hybrid EMD-AR model for nonlinear and non-stationary wave forecasting
Wen-yang Duan, Li-min Huang, Yang Han, De-tai Huang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2016, 17(2): 115-129.   https://doi.org/10.1631/jzus.A1500164
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Accurate wave forecasting with a couple of hours of warning time offers improvements in safety for maritime operation-related activities. Autoregressive (AR) model is an efficient and highly adaptive approach for wave forecasting. However, it is based on linear and stationary theory and hence has limitations in forecasting nonlinear and non-stationary waves. Inspired by the capability of empirical mode decomposition (EMD) technique in handling nonlinear and non-stationary signals, this paper describes the development of a hybrid EMD-AR model for nonlinear and non-stationary wave forecasting. The EMD-AR model was developed by coupling an AR model with the EMD technique. Nonlinearity and non-stationarity were overcome by decomposing the wave time series into several simple components for which the AR model is suitable. The EMD-AR model was implemented using measured significant wave height data from the National Data Buoy Center, USA. Prediction results from various locations consistently show that the hybrid EMD-AR model is superior to the AR model. This demonstrates that the EMD technique is effective in processing nonlinear and non-stationary waves.
A meshless method based on moving least squares for the simulation of free surface flows
Yu Lu, An-kang Hu, Ya-chong Liu, Chao-shuai Han
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2016, 17(2): 130-143.   https://doi.org/10.1631/jzus.A1500053
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In this paper, a meshless method based on moving least squares (MLS) is presented to simulate free surface flows. It is a Lagrangian particle scheme wherein the fluid domain is discretized by a finite number of particles or pointset; therefore, this meshless technique is also called the finite pointset method (FPM). FPM is a numerical approach to solving the incompressible Navier–Stokes equations by applying the projection method. The spatial derivatives appearing in the governing equations of fluid flow are obtained using MLS approximants. The pressure Poisson equation with Neumann boundary condition is handled by an iterative scheme known as the stabilized bi-conjugate gradient method. Three types of benchmark numerical tests, namely, dam-breaking flows, solitary wave propagation, and liquid sloshing of tanks, are adopted to test the accuracy and performance of the proposed meshless approach. The results show that the FPM based on MLS is able to simulate complex free surface flows more efficiently and accurately.
Synthesis of ferrocene- and azobenzene-based compounds for anion recognition
Xiao-ting Zhai, Hao-jie Yu, Li Wang, Zheng Deng, Zain-ul Abdin, Yong-sheng Chen
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2016, 17(2): 144-154.   https://doi.org/10.1631/jzus.A1500183
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A series of ferrocene- and azobenzene-based compounds with acyl amine groups attached were designed and synthesized to explore their potential application in anion recognition. Their electro- and photo-properties, and the effect of nitro and amine substituents of the benzene ring on anion recognition were studied by UV-vis absorption spectroscopy (UV) and cyclic voltammetry (CV). The results showed that a nitro group substituent has a positive effect on the binding affinity and sensitivity, which might be due to the strong hydrogen bonding interaction between the receptor and the guest, while an amino group substituent has a negative effect on the sensitivity. Furthermore, the shift in the UV-vis absorption spectra was observed as a color change, which can be used for the naked-eye detection of F and H2PO4.
A novel organosilicon-based ionic plastic crystal as solid-state electrolyte for lithium-ion batteries
Xin-yue Zhao, Jing-lun Wang, Hao Luo, Hu-rong Yao, Chu-ying Ouyang, Ling-zhi Zhang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2016, 17(2): 155-162.   https://doi.org/10.1631/jzus.A1500099
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A novel organosilicon-based ionic plastic crystal, N,N,N,-diethylmethyl-N-[(trimethylsilyl)methyl]ammonium bistrifluoromethane sulfonimide ([DTMA][TFSI]) was designed and synthesized as solid-state electrolyte for lithium-ion batteries. The chemical structure and the physical and electrochemical properties were characterized in detail. The ionic conductivity of [DTMA][TFSI] was improved significantly by doping with lithium oxalyldifluoroborate (LiODFB) and propylene carbonate (PC). An optimized plastic crystal composite ([DTMA][TFSI]:LiODFB:PC=8:1: molar ratio) as a solid-state electrolyte exhibited a decent cycling stability in LiFePO4/Li half-cell, with a specific discharge capacity of 144 mA·h/g and capacity retention of 94% after 50 cycles at C/20.
Asymmetric synthesis of N-protected 3-methylpiperidin-2-one and its diastereoisomer
Xiao-zhong Wang, Xia Wang, Ying-qi Chen, Li-yan Dai, Xing-cong Li
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2016, 17(2): 163-170.   https://doi.org/10.1631/jzus.A1500008
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This paper reports the asymmetric synthesis of an important pharmaceutical intermediate (3S)-1-[(1R)-2-hydroxy-1-phenylethyl]-3-methylpiperidin-2-one (compound 1) from commercially available D-plenylglycinol and delta-valerolactone. During the alkylation process, the hydroxyl group can be protected or unprotected, resulting in a different consumption of s-BuLi, and leading to a different diastereomeric excess (de) of compound 1. When 1-[(1R)-2-hydroxy-1-phenylethyl]-piperidin-2-one (compound 2) was alkylated with 2.5 eq. of s-BuLi, compound 1 was obtained as a single isomer detected by chiral high performance liquid chromatography (HPLC) columns with an overall yield of 91%. With the hydroxyl group protected, (R)-1-(2-[(tert-butyldimethylsil) oxy]-1-phenylethyl) piperidine-2-one (compound 6) could be alkylated with 1.5 eq. of s-BuLi, giving compound 1 and its diastereoisomer 8 in a ratio of 1:2.5 and a yield of methylation of 90%. Compounds 1 and 8 could be separated completely and easily by flash chromatography. The absolute configuration of compound 8 was determined by single-crystal X-ray analysis. The mechanism of the alkylation process is discussed based on experimental results.
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