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Simulation of Non-Spherical Rice Seed Motion in Pneumatic Conveying with Bend by CFD-DEM
Jun Du,Yifan Heng,Junfang Xia,Mengjie Hu,Gang Zou 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.3
The rice flow characteristics in pneumatic conveying determined the performance of pneumatic metering device for rice seed. The non-spherical rice seed motion in pneumatic conveying with bend was investigated by CFD-DEM simulation. The rice seed particle model was established by multi-sphere method, and a typical pneumatic conveying horizontal-vertical pipe with bend was selected. The applicability of three drag force models on non-spherical particle was compared. The particle flow characteristics in different pipes including the vertical-horizontal pipe and the horizontal-horizontal pipe were investigated. The non-spherical particle formed a particle rope at the outlet of bend, and the particle rope dispersed at downstream of the vertical pipe. The effect of particle shape on gas-solid flow characteristics was obtained. The gas velocity value in the bend for non-spherical rice particle was higher than that for spherical particle. The non-spherical rice particle rope dispersed more slowly than the spherical particle rope. The particle velocity profile of non-spherical and spherical particles was similar. The differences of the gas-solid flow predicted by Free stream model, Ergun and Wen & Yu model, and De Filice model were limited. The particle rope can also be formed in vertical-horizontal pipe and horizontal-horizontal pipe, but its dispersion represented different features. The results showed that particle shape and structure of pipe can influence the gas-solid flow characteristics, and a suitable particle model was important for the gas-solid flow simulation by CFD-DEM.
Potential Methane Production on Anaerobic Co-digestion of Swine Manure and Food Waste
Shin, Joung-Du,Park, Sang-Won,Kim, Sang-Hyoun,Duangmanee, Jack,Lee, Po-Heng,Sung, Shi-Hwu,Lee, Bong-Hoon The Korean Society of Environmental Agriculture 2008 한국환경농학회지 Vol.27 No.2
Anaerobic co-digestion of swine manure and food waste for biogas production was performed in serum bottles at various volatile solids(VS) contents and mixing ratios of two substrates(swine manure:food waste=$100:0{\sim}0:100$). Through kinetic mode of surface methodology, the methane production was fitted to a Gompertz equation. The ultimate methane production potential of swine manure alone was lower than that of food waste regardless of VS contents. However, it was appeared that maximum methane production potentials in 80 : 20 of the mixing rate at VS 3% was enhanced at 144.7%, compared to its only swine manure. The potential increased up to 815.71 ml/g VS fed as VS concentration and food composition increased up to 3.0% and 20%, respectively. The ultimate amount of methane produced had significantly a positive relationship with that of methane yield rate. Overall, it would be strongly recommended that feeding stocks use 20% of mixing ratio of food waste based on VS 3% contents when operating the anaerobic reactor on site at $35^{\circ}C$ if not have treatment of its anaerobic waste water.
Xuelong Li,Heng Du,Jia Li,Xianliang Li,Qingchun Gao,Xiangyan Chen 대한신경과학회 2023 Journal of Clinical Neurology Vol.19 No.4
Background and Purpose By measuring a newly defined parameter, the carotid–cerebral pulse wave velocity (ccPWV), this study aimed to determine the association of intracranial artery calcification (IAC) with arterial stiffness as reflected by the pulse wave velocity between the carotid and middle cerebral arteries using transcranial Doppler sonography in patients with acute stroke. Methods We recruited 146 patients with ischemic stroke from our stroke center. Computed tomography of the head was used to assess the presence and severity of IAC. Arterial stiffness was evaluated using ccPWV. Data are presented as quartiles of ccPWV. A multivariable logistic regression model was used to assess the independent relationship between ccPWV and IAC. Results The IAC prevalence increased with the ccPWV quartile, being 54%, 76%, 83%, and 89% for quartiles 1, 2, 3, and 4, respectively (p<0.001) as did IAC scores, with median [interquartile range] values of 0 [0–2], 3 [2–4], 4 [2–5], and 5 [4–6], respectively (p<0.001). After additionally adjusting for age and hypertension, a significant correlation was only found between quartiles 3 and 4 of ccPWV and IAC scores. The odds ratio (95% confidence interval) for the IAC scores was 1.78 (1.28–2.50) (p=0.001) in quartile 4 of ccPWV and 1.45 (1.07–1.95) (p=0.015) in quartile 3 compared with quartile 1. Conclusions We found that in patients with acute ischemic stroke, ccPWV was positively related to the degree of IAC. Future longitudinal cohort studies may help to identify the potential role of IAC in the progression of cerebral arterial stiffness.
Wang, Guoning,Du, Xiong,Shi, Ying,Tai, Heng-Ming,Ji, Yongliang The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
Frequency coupling in the phase domain is a recently reported phenomenon for phase locked loop (PLL) based three-phase grid-inverter systems. This paper investigates the mechanism and stabilization method for the frequency coupling to the stability of grid-inverter systems. Self and accompanying admittance models are employed to represent the frequency coupling characteristics of the inverter, and a small signal equivalent circuit of a grid-inverter system is set up to reveal the mechanism of the frequency coupling to the system stability. The analysis reveals that the equivalent inverter admittance is changed due to the frequency coupling of the inverter, and the system stability is affected. In the end, retuning the bandwidth of the phase locked loop is presented to stabilize the three-phase grid-inverter system. Experimental results are given to verify the analysis and the stabilization scheme.
Huang, Xiaoyong,Li, Bin,Du, Peng,Guo, Heng,Cao, Renping,Yu, Jae Su,Wang, Kai,Sun, Xiao Wei Elsevier 2018 Dyes and pigments Vol.151 No.-
<P><B>Abstract</B></P> <P>In this paper, we reported on multicolor emission tuning in Tb<SUP>3+</SUP> and Eu<SUP>3+</SUP> co-doped CaGd<SUB>2</SUB>(WO<SUB>4</SUB>)<SUB>4</SUB> phosphors prepared by a traditional high-temperature solid-state reaction. Upon 380 nm ultraviolet excitation, the emission color of CaGd<SUB>2</SUB>(WO<SUB>4</SUB>)<SUB>4</SUB>:Tb<SUP>3+</SUP>,Eu<SUP>3+</SUP> phosphors can be readily tuned from green to yellow, orange and finally to pure red through varying the concentration ratio of Eu<SUP>3+</SUP> and Tb<SUP>3+</SUP> ions. The energy transfer mechanism from Tb<SUP>3+</SUP> to Eu<SUP>3+</SUP> was systematically investigated by photoluminescence spectra, luminescence decay times, and time-resolved spectra. The internal quantum efficiencies of these phosphors were measured, and their thermal stability was also studied. A prototype white light-emitting diode (LED) device was fabricated by using an ultraviolet chip combined with a blend of blue-emitting BaMgAl<SUB>10</SUB>O<SUB>l7</SUB>:Eu<SUP>2+</SUP> phosphors, green-emitting BaSrSiO<SUB>4</SUB>:Eu<SUP>2+</SUP> phosphors, and red-emitting CaGd<SUB>2</SUB>(WO<SUB>4</SUB>)<SUB>4</SUB>:50%Tb<SUP>3+</SUP>,50%Eu<SUP>3+</SUP> phosphors. All the results indicate that the CaGd<SUB>2</SUB>(WO<SUB>4</SUB>)<SUB>4</SUB>:Tb<SUP>3+</SUP>,Eu<SUP>3+</SUP> has great potential application in lighting and displays.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CaGd<SUB>2</SUB>(WO<SUB>4</SUB>)<SUB>4</SUB>:Tb<SUP>3+</SUP>,Eu<SUP>3+</SUP> showed efficient energy-transfer from Tb<SUP>3+</SUP> to Eu<SUP>3+</SUP>. </LI> <LI> CaGd<SUB>2</SUB>(WO<SUB>4</SUB>)<SUB>4</SUB>:Tb<SUP>3+</SUP>,Eu<SUP>3+</SUP> exhibited tunable color emission under 380 nm excitation. </LI> <LI> The energy-transfer mechanism was studied in detail. </LI> <LI> Quantum efficiency and thermal stability were investigated. </LI> <LI> The proof-of-concept LED lamps were fabricated by employing phosphors and UV LEDs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Guoning Wang,Xiong Du,Ying Shi,Heng-Ming Tai,Yongliang Ji 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
Frequency coupling in the phase domain is a recently reported phenomenon for phase locked loop (PLL) based three-phase grid-inverter systems. This paper investigates the mechanism and stabilization method for the frequency coupling to the stability of grid-inverter systems. Self and accompanying admittance models are employed to represent the frequency coupling characteristics of the inverter, and a small signal equivalent circuit of a grid-inverter system is set up to reveal the mechanism of the frequency coupling to the system stability. The analysis reveals that the equivalent inverter admittance is changed due to the frequency coupling of the inverter, and the system stability is affected. In the end, retuning the bandwidth of the phase locked loop is presented to stabilize the three-phase grid-inverter system. Experimental results are given to verify the analysis and the stabilization scheme.
Empirical likelihood for the class of single index hazard regression models
Jianbo Li,Minglong Guo,Changxin Du,Riquan Zhang,Heng Lian 한국통계학회 2015 Journal of the Korean Statistical Society Vol.44 No.4
Based on the B spline approximation technique and right censored data, we consider the empirical likelihood inference for the index parameters and its partial components in a class of single index hazard regression models. Under some regular conditions, we show that our proposed empirical likelihood ratio statistics follow the standard χ2 distribution. Some numerical studies are given to illustrate our proposed methodology.
Study on the Fracture Properties of the PMMA Structure for the JUNO Central Detector
Zongyi Wang,Yuanqing Wang,Xinxi Du,Tianxiong Zhang,Yuekun Heng 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6
Polymethyl methacrylate (PMMA) is increasingly used in building structures nowadays. PMMA materials utilized in structures have different fracture property compared with those used in aircrafts or biomedical equipment. Single-edge-notch bending (SENB) tests were firstly carried out at various temperatures (-40°C, -20°C, 0°C, 20°C, and 40°C) to determine the KIC values of base PMMA materials and connected areas. The crack-resisting capacity of PMMA plate is subsequently studied. The fracture property of the PMMA joint for the Jiangmen Underground Neutrino Observatory (JUNO) central detector is investigated. The results show that base PMMA material has higher KIC values than connected area. The KIC of base PMMA material is lowest at 20°C and highest at -20°C, while that of connected area is lowest at 40°C and highest at -40°C. For the PMMA joint of the JUNO detector, the cracks perpendicular to the X axis are more disadvantageous than those perpendicular to the Z axis. The stress intensity factors (SIFs) at the crack front of the embedded crack decrease with the increase of embedded depth. Due to the presence of two parallel surface or embedded cracks, the SIFs at the crack front decrease.