numerica1 study of fluid flow and heat transfer in different microchannel heat sinks for electronic chip cooling

Shanglong Xu,Guangxin Hu,Jie Qin,Yue Yang 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.4

Four different microchannel heat sinks are designed to study the effects of structures in microchannel heat sinks for electronic chips cooling. Based on the theoretic analysis and numerical computation of flow and heat exchange characteristics, the electronic chip’s temperature and flow rate distributions are obtained. The correspondence between flow pressure drop and chip’s temperature in the four microchannel heat sinks is also studied and analyzed. Numerically analyzed results indicate that the topological structure in microchannel heat sink has a significant influence on electronic chips cooling. This study shows various thermal properties in the four microchannel heat sinks.

Speed Sensorless Control of Bearingless Induction Motors Based on Adaptive Flux Observer

Fang Wenxin,Yang Zebin,Sun Xiaodong,Wang Guangxin,Xu Ting 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.3

To realize the speed self-identifi cation of the suspension rotor in the low-cost operation control of a bearingless induction motor (BIM), a speed sensorless control strategy based on the adaptive fl ux observer is proposed. Firstly, the stability condition of the observer is analyzed by the small-signal linearization method, and the output errors of the observer in two stationary coordinate systems are transformed into the rotor magnetic fi eld rotating coordinate, and condition of the error feedback matrix satisfying the observer stability is obtained. Secondly, based on the construction of the full-order model of the controlled object, a feedback loop containing the measured object and its variable is designed, and a reduced-order speed observer is constructed to realize the speed self-identifi cation of the BIM. Finally, simulation and experimental verifi cation research are carried out on the BIM speed sensorless vector control system. Both simulation and experiment results show that the proposed speed self-identifi cation method can not only realize speed sensorless operation under no-load, speed change, an abrupt change of load eff ectively, but also make the motor has a good suspension performance.

Pea starch increases the dry matter flow at the distal ileum and reduces the amino acids digestibility in ileal digesta collected after 4 hours postprandial of pigs fed low-protein diets

Zhou Junyan,Wang Lu,Yang Guangxin,Yang Lijie,Zeng Xiangfang,Qiao Shiyan 아세아·태평양축산학회 2022 Animal Bioscience Vol.35 No.7

Objective: The study was aimed to investigate the rules of postprandial changes in intestine digesta dry matter (DM) flow and amino acid digestibility of growing pigs fed low-protein (LP) diets made of different starch. Methods: Eight barrows (28.8±2.1 kg) with a T-cannula at the distal ileum were randomly allotted to an 8×3 Youden square design. Treatments included: waxy corn starch LP (WLP); corn starch LP (CLP) and pea starch LP (PLP). Diets were given at 08:00 and 20:00. Digesta samples were collected in six 2-h stages from 08:00 to 20:00. Results: The Cr concentrations of ileal digesta increased and then decreased in WLP and CLP, while increased continuously in PLP as time passed after postprandial (p<0.05). Higher average Cr concentrations (0.78% and 0.84% vs 0.70%; p<0.05) and lower average DM flow (181.1 g/kg and 166.3 g/kg vs 240.3 g/kg; p<0.001) were observed in WLP and CLP, compared with PLP. The apparent ileal digestibility coefficient of most amino acids in WLP and CLP increased compared with that in PLP. No difference in lysine or methionine digestibility was observed. When digesta were collected in 2-h periods, the apparent ileal digestibility coefficient of amino acids did not change over time. When digesta was collected in 4-h periods from 16:00 to 20:00 and 6-h periods from 14:00 to 20:00 (p<0.05), WLP and CLP showed markedly higher amino acid digestibility than PLP Conclusion: High-amylose slowly digested starch can increase the DM flow at the distal ileum and reduce the apparent ileal digestibility coefficient of amino acids of pigs fed LP diets. Compared with waxy corn starch and corn starch, pea starch reduced the digestibility of amino acids in digesta collected after 4 h postprandial. Objective: The study was aimed to investigate the rules of postprandial changes in intestine digesta dry matter (DM) flow and amino acid digestibility of growing pigs fed low-protein (LP) diets made of different starch.Methods: Eight barrows (28.8±2.1 kg) with a T-cannula at the distal ileum were randomly allotted to an 8×3 Youden square design. Treatments included: waxy corn starch LP (WLP); corn starch LP (CLP) and pea starch LP (PLP). Diets were given at 08:00 and 20:00. Digesta samples were collected in six 2-h stages from 08:00 to 20:00.Results: The Cr concentrations of ileal digesta increased and then decreased in WLP and CLP, while increased continuously in PLP as time passed after postprandial (p<0.05). Higher average Cr concentrations (0.78% and 0.84% vs 0.70%; p<0.05) and lower average DM flow (181.1 g/kg and 166.3 g/kg vs 240.3 g/kg; p<0.001) were observed in WLP and CLP, compared with PLP. The apparent ileal digestibility coefficient of most amino acids in WLP and CLP increased compared with that in PLP. No difference in lysine or methionine digestibility was observed. When digesta were collected in 2-h periods, the apparent ileal digestibility coefficient of amino acids did not change over time. When digesta was collected in 4-h periods from 16:00 to 20:00 and 6-h periods from 14:00 to 20:00 (p<0.05), WLP and CLP showed markedly higher amino acid digestibility than PLPConclusion: High-amylose slowly digested starch can increase the DM flow at the distal ileum and reduce the apparent ileal digestibility coefficient of amino acids of pigs fed LP diets. Compared with waxy corn starch and corn starch, pea starch reduced the digestibility of amino acids in digesta collected after 4 h postprandial.

Effect of specific functional groups on oil adhesion from mica substrate: Implications for low salinity effect

Jiazhong Wu,Fanghui Liu,Hui Yang,Shijing Xu,Quan Xie,Minghui Zhang,TING CHEN,Guangxin Hu,Jinben Wang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.56 No.-

Low salinity effect has been in the center of attention as a cost-effective and environmentally friendlytechnique. Wettability alteration of the oil/brine/mica system appears to be the identified mechanism(s)to trigger the low salinity effect. While the effect of water chemistry and minerology on the wettability ofthe system has been extensively investigated, few studies have investigated the effect of specific functiongroups from crude oil on the system wettability, limiting the understanding of how specific functionalgroup contributes to the wettability. We thus experimentally measured the adhesion forces betweenmica surfaces and functional groups (e.g., C6H5–, CH3–, COOH–, and NH2–) in the presence of differentaqueous ionic solutions using chemical force microscopy (CFM). Moreover, to understand thecontribution of the structural force, the traditional Derjaguin–Landau–Verwey–Overbeek (DLVO) theorywas extended (denoted as EDLVO) tofit the force profiles using a Gauss model. Our results showed thatthe adhesion force between mica and functional groups in a decreasing order was –NH2> –COOH> –CH3> –C6H5. We also found that while DLVO forces strongly affected the tip-surface contact due to theinteractions among oil/brine/mica interfaces, the structural forces also played an important role in adistance of 1–20 nm due to the presence of H-bonds between COOH-terminated or NH2-terminated tipand mica surface. We therefore conclude that the structural force largely contributes to the adhesionforce due to the hydrophilicity or polarity of functional groups, and nucleophilic property (such as phenylgroup). Our results suggest that the polarity of the crude oil needs to be considered to screen a candidatereservoir for low salinity waterflooding projects.

Isolation and characterization of a novel piezotolerant bacterium Lysinibacillus yapensis sp. nov., from deep-sea sediment of the Yap Trench, Pacific Ocean

Libo Yu,Xixiang Tang,Shiping Wei,Yinkun Qiu,Xiashutong Xu,Guangxin Xu,Qilin Wang,Qian Yang 한국미생물학회 2019 The journal of microbiology Vol.57 No.7

A Gram-positive, aerobic, rod-shaped, spore-forming bacterium, designated YLB-03T, with peritrichous flagella was isolated from deep-sea sediment of the Yap Trench at a depth of 4435 m. The bacterium was found to be catalase-positive but oxidase-negative. Growth of this bacterium was observed at 15–50°C (optimum 37°C), pH 5–10.5 (optimum 7), 0–5% NaCl (optimum 1%, w/v) and 0.1–50 MPa (optimum 0.1 MPa). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YLB-03T was a member of the genus Lysinibacillus. Strain YLB-03T was closely related to Lysinibacillus sinduriensis BLB-1T and Lysinibacillus chungkukjangi 2RL3-2T (98.4%), Lysinibacillus halotolerans LAM- 612T (98.0%), Lysinibacillus telephonicus KT735049T (97.5%), Lysinibacillus endophyticus C9T (97.5%), Lysinibacillus composti NCCP-36T and Lysinibacillus massiliensis 4400831T (97.3%). The ANI and the GGDC DNA-DNA hybridization estimate values between strain YLB-03T and closely related type strains were 73.7–76.3% and 34.7–38.7%, respectively. The principal fatty acids were anteiso-C15:0 and iso-C15:0. The G+C content of the chromosomal DNA was 39.6 mol%. The respiratory quinone was determined to be MK-7. The diagnostic amino acids in the cell wall peptidoglycan contained Lys-Asp (type A4α) and the cell-wall sugars were glucose and xylose. The polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and an unidentified phospholipid. The combined genotypic and phenotypic data showed that strain YLB-03T represents a novel species within the genus Lysinibacillus, for which the name Lysinibacillus yapensis sp. nov. is proposed, with the type strain YLB-03T (= MCCC 1A12698T = JCM 32871T).