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Study of the Application of Fructooligosaccharides in Piglets
Chuanlai Xu,Xudong Chen,Cheng Ji,Qiugang Ma,Kai Hao 아세아·태평양축산학회 2005 Animal Bioscience Vol.18 No.7
In this study, 90 crossbred weaned pigs (Duroc횞Landrace횞Large White) weighing ~ 7.86짹0.06 kg each were randomly allotted to one of three dietary treatments. Control pigs were a fed corn-soybean meal diet with no additives. The two treatment groups were fed the basal diet supplemented either with 75 mg/kg Aureomycin or 0.4% fructooligosaccharides (FOS) in order to study the effects on performance, serological indices, and enteric morphology in addition to examining the content of volatile fatty acids in intestinal digesta. The results indicate that the diets containing FOS and antibiotics had a significant effect on feed conversion ratios (FCR) and diarrhea incidence, as well as increasing the concentrations of isobutyric and butyric acid and total VFAs in the caecum, and acetic acid, isovaleric acid, and total VFAs in feces. Supplementation with FOS also resulted in significantly longer mucosal villi height and a higher percentage of goblet cells compared with the control. No difference was found in crypt depth among the three treatments. While serum glucose levels were significantly higher following FOS supplement, differences in serum total protein, albumin, globulin, and urea nitrogen levels were not significant.
Zhang Siyan,Wang Xudong,Ma Junjie,Duan Ruizhen,Zhou Kai 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4
The dead-time setting in space vector pulse width modulation (SVPWM) causes inverter output waveform distortion and performance degradation. This paper proposes a novel dead-time segmented compensation strategy for a wide impedance angle range in a three-phase inverter with a resistance-inductance load. Since the load impedance angle ( φ ) of the threephase inverter produces diff erent dead-time eff ects, in this paper, it is divided into two intervals of [0 30°] and [30° 90°] and a corresponding dead-time segmented compensation strategy is proposed, which solves the limitation of the traditional time compensation scheme that analyzes only the resistive load. In addition, this paper uses the conversion relationship between the power factor ( λ ) and φ to determine the current polarity of each sector in the vector space, which avoids the detection error of the current zero-crossing point in the traditional compensation scheme. The simulation and experimental results demonstrate that this method eff ectively reduces the total harmonic distortion (THD) of the inverter output current signal by approximately 30% and is easy to program, which improves the inverter output performance.
Shengjie Yao,Lei Sun,Xudong Ma 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.5
This paper presents the deformation behavior and crashworthiness of electric resistance welded mild steel tubes with axial gradient microstructures in quasi-static compression. Three sets of tubes were prepared, and regions of each tube were Induction heated and directly quenched (IH-DQ). The effect of the length to diameter (L/D) ratio, and length of the IH-DQ region on crushing characteristics was investigated, and compared with untreated tubes. The compression tests revealed that improved energy absorption can be obtained in IHDQ tubes if the collapse is controlled by the formation of a concertina buckling mode. However, there was a tendency to produce mixed or Euler buckling modes as the ratio of L/D increased. Meanwhile, the results of the crush experiments and the FEM models showed that the heat-treatment process should be precisely controlled to produce the correct type of microstructure, and circumferential uniformity of microstructure distribution.
Gui-bo Nie,Chenxiao Zhang,Xudong Zhi,Kun Liu,Huihuan Ma 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.2
Q235B and Q345B are two structural steel grades widely used in China. In previous studies, more precisely in 2012, Nie defi ned a normalized constitutive model using material damage accumulation to describe damage behavior of Q235B steel in circular tubes. This paper focuses on the hysteretic damage behavior of Q345B steel in a circular steel tube under cyclic loads and describes the damage mechanism through a damage constitutive model based on experimental results. Three equations are implemented in the constitutive model, which includes a damage index to accurately describe the plastic and damage behavior of the material. Experiments were conducted in which a cyclic loading is applied in three directions on a circular steel tube. The constitutive model was implemented in the ABAQUS FEA software through a user-defi ned subroutine. Some parameters in the constitutive model were calibrated based on the experimental and numerical results. The performance behavior of a single-layer reticulated dome under seismic motion record was investigated through the increment dynamic analysis method. The results indicate that the constitutive model is suitable for analyses and quantifying seismic damage accumulation and progressive failure and it is also benefi cial for investigating the nonlinear dynamic behavior of structures under seismic loads. The eff ect of accumulated material damage can describe large-scale structural deformation and obvious reduction in the failure limit load.
An investigation into the thermo-elasto-hydrodynamic effect of notched mechanical seals
Xiangkai Meng,Yujie Qiu,Yi Ma,Xudong Peng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.6
A 3D thermo-elasto-hydrodynamic model is developed to analyze the sealing performance of a notchedmechanical seal applied in the reactor coolant pump. In the model, the generalized Reynolds equation,the energy equation coupled with notch heat balance equation, the heat conduction equations, and thedeformation equations of the sealing rings are iteratively solved by the finite element method. The filmpressure and temperature distribution are obtained, and the deformation of the sealing rings is revealedto study the mechanism of the notched mechanical seals. A parameterized study is conducted to analyzethe sealing performance under different operating conditions. As a comparison, the sealing performanceof non-notched seals is also studied. The results show that the hydrostatic effect is dominant in the loadcarrying capacity of the fluid film due to the radial mechanical and thermal deformations. The notch cancool the fluid film and influence the thermal deformation of seal rings. The sealing performance issensitive to the pressure difference, ambient temperature, and rotational speed. It is suggested to set thenotches on the softer sealing rings to acquire the greater hydrodynamic effect. Compared with the nonnotched, the notched end face holds a better lubrication performance, especially under lower rotationalspeed.