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EXPERIMENTAL STUDY ON A NOVEL DEFROST CYCLE FOR AIR SOURCE HEAT PUMP
Guo, Xian-Min,Wang, Ya-Jing,Fu, Wen-Cheng,Tao, Xiang-Cheng The Society of Air-Conditioning and Refrigerating 2010 International Journal Of Air-Conditioning and Refr Vol.18 No.1
On the basis of the hot-gas bypass defrost cycle, a new defrost method for air source heat pump is proposed. In the new defrost cycle, the outdoor heat exchanger is divided into two parts which are connected by a capillary tube. The front and rear parts of the heat exchanger are used as the evaporator and condenser respectively during defrosting, and can be defrosted orderly by using the four-way valve. The defrosting performance of the new cycle is investigated experimentally and the results are compared with that of the reverse-cycle defrost system. The experimental results indicate that the energy is used more efficiently in the new defrost cycle, therefore, the defrosting duration and losses are less than those of the reverse-cycle defrost system. Moreover, it does not extract heat from the indoor space during defrosting in terms of the new defrost cycle. Compared with the reverse-cycle defrost system, it is found that the switching times of the four-way valve in the new defrost system are the same, and the fluctuation of the discharge and suction pressures during the defrosting is much less than that in the reverse-cycle defrosting, hence, the mechanical impact on the system is much less.
Comparative Proteomic Analysis of Yak Follicular Fluid during Estrus
Guo, Xian,Pei, Jie,Ding, Xuezhi,Chu, Min,Bao, Pengjia,Wu, Xiaoyun,Liang, Chunnian,Yan, Ping Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.9
The breeding of yaks is highly seasonal, there are many crucial proteins involved in the reproduction control program, especially in follicular development. In order to isolate differential proteins between mature and immature follicular fluid (FF) of yak, the FF from yak follicles with different sizes were sampled respectively, and two-dimensional gel electrophoresis (2-DE) of the proteins was carried out. After silver staining, the Image Master 2D platinum software was used for protein analysis and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) was performed for differential protein identification. The expression level of transferrin and enolase superfamily member 1 (ENOSF1) was determined by Western blotting for verification analysis. The results showed that 2-DE obtained an electrophoresis map of proteins from mature and immature yak FF with high resolution and repeatability. A comparison of protein profiles identified 12 differently expressed proteins, out of which 10 of them were upregulated while 2 were downregulated. Western blotting showed that the expression of transferrin and ENOSF1 was enhanced with follicular development. Both the obtained protein profiles and the differently expressed proteins identified in this study provided experimental data related to follicular development during yak breeding seasons. This study also laid the foundation for understanding the microenvironment during oocyte development.
Guo Xian,Jeong mok Oh(오정목),Junghoon Lee(이정훈),Sangmyung Cho(조상명),Jongtak Yeom(엄종탁),Yoonsuk Choi(최윤석),Namhyun Kang(강남현) 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
Wire arc additive manufacturing (WAAM) is a process that combines an electric arc as a heat source and a wire as feedstock to build a component layer by layer. In arc welding, heat input is an important characteristic because it influences the cooling rate, which could affect the mechanical properties and microstructure of the deposition part. We investigated the effect of heat input on the microstructure and mechanical property of the additive layer manufactured for Ti64 alloys. High-heat input (H; 1 kJ/mm) produced a columnar grain exhibiting a large anisotropic property of tensile strength. Low-heat input (L; 0.5 kJ/mm) transformed the columnar grains to the equiaxed ones, and its reason was associated with the solidification cooling rates accelerated. However, the H specimens exhibited a larger tensile strength and hardness than the L specimens, which can be explained by volume fraction of the hardened phase (α’ martensite and secondary α). The microstructure in H and L specimens were further identified by SEM-EDX and TEM. The thermal history in the WAAM deposits was also simulated using finite element method. At the certain temperature gradient, the faster cooling rates produced the more fraction of the equiaxed grains. Furthermore, the H specimens exhibited more thermal cycles calculated to verify the condition that can produce more α’ martensite and secondary α. Therefore, the L specimen changed the grain structure to equiaxed one and reduced the anisotropy of tensile strength significantly.
Guo Xian,Jeong mok Oh(오정목),Junghoon Lee(이정훈),Sangmyung Cho(조상명),Jongtak Yeom(엄종탁),Yoonsuk Choi(최윤석),Namhyun Kang(강남현) 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
Wire arc additive manufacturing (WAAM) is a process that combines an electric arc as a heat source and a wire as feedstock to build a component layer by layer. In arc welding, heat input is an important characteristic because it influences the cooling rate, which could affect the mechanical properties and microstructure of the deposition part. We investigated the effect of heat input on the microstructure and mechanical property of the additive layer manufactured for Ti64 alloys. High-heat input (H; 1 kJ/mm) produced a columnar grain exhibiting a large anisotropic property of tensile strength. Low-heat input (L; 0.5 kJ/mm) transformed the columnar grains to the equiaxed ones, and its reason was associated with the solidification cooling rates accelerated. However, the H specimens exhibited a larger tensile strength and hardness than the L specimens, which can be explained by volume fraction of the hardened phase (α’ martensite and secondary α). The microstructure in H and L specimens were further identified by SEM-EDX and TEM. The thermal history in the WAAM deposits was also simulated using finite element method. At the certain temperature gradient, the faster cooling rates produced the more fraction of the equiaxed grains. Furthermore, the H specimens exhibited more thermal cycles calculated to verify the condition that can produce more α’ martensite and secondary α. Therefore, the L specimen changed the grain structure to equiaxed one and reduced the anisotropy of tensile strength significantly.
Guo Xian,Jeong mok Oh(오정목),Junghoon Lee(이정훈),Sangmyung Cho(조상명),Jongtak Yeom(엄종탁),Yoonsuk Choi(최윤석),Namhyun Kang(강남현) 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
Wire arc additive manufacturing (WAAM) is a process that combines an electric arc as a heat source and a wire as feedstock to build a component layer by layer. In arc welding, heat input is an important characteristic because it influences the cooling rate, which could affect the mechanical properties and microstructure of the deposition part. We investigated the effect of heat input on the microstructure and mechanical property of the additive layer manufactured for Ti64 alloys. High-heat input (H; 1 kJ/mm) produced a columnar grain exhibiting a large anisotropic property of tensile strength. Low-heat input (L; 0.5 kJ/mm) transformed the columnar grains to the equiaxed ones, and its reason was associated with the solidification cooling rates accelerated. However, the H specimens exhibited a larger tensile strength and hardness than the L specimens, which can be explained by volume fraction of the hardened phase (α’ martensite and secondary α). The microstructure in H and L specimens were further identified by SEM-EDX and TEM. The thermal history in the WAAM deposits was also simulated using finite element method. At the certain temperature gradient, the faster cooling rates produced the more fraction of the equiaxed grains. Furthermore, the H specimens exhibited more thermal cycles calculated to verify the condition that can produce more α’ martensite and secondary α. Therefore, the L specimen changed the grain structure to equiaxed one and reduced the anisotropy of tensile strength significantly.
EXPERIMENTAL STUDY ON A NOVEL DEFROST CYCLE FOR AIR SOURCE HEAT PUMP
XIAN-MIN GUO,YA-JING WANG,WEN-CHENG FU,XIANG-CHENG TAO 대한설비공학회 2010 International Journal Of Air-Conditioning and Refr Vol.18 No.1
On the basis of the hot-gas bypass defrost cycle, a new defrost method for air source heat pump is proposed. In the new defrost cycle, the outdoor heat exchanger is divided into two parts which are connected by a capillary tube. The front and rear parts of the heat exchanger are used as the evaporator and condenser respectively during defrosting, and can be defrosted orderly by using the four-way valve. The defrosting performance of the new cycle is investigated experimentally and the results are compared with that of the reverse-cycle defrost system. The experimental results indicate that the energy is used more e±ciently in the new defrost cycle, therefore, the defrosting duration and losses are less than those of the reverse-cycle defrost system. Moreover, it does not extract heat from the indoor space during defrosting in terms of the new defrost cycle. Compared with the reverse-cycle defrost system, it is found that the switching times of the fourway valve in the new defrost system are the same, and the fluctuation of the discharge and suction pressures during the defrosting is much less than that in the reverse-cycle defrosting, hence, the mechanical impact on the system is much less.
Xian-guo Cheng,Guo-hong Yu,Sheng-cai Huang,Rui He,Ying-Zhang Li 한국식물학회 2018 Journal of Plant Biology Vol.61 No.6
Mitochondrial phosphate transporter plays animportant regulatory role in promoting the uptake andtransport of phosphate in plants. In this study, the SlMPT3;1gene, a member of mitochondrial phosphate transporterfamily in tomato, was isolated and transformed into the riceOryza sativa L. ssp. japonica cultivar Kitaake. The SlMPT3;1 islocalized to the mitochondrial membrane and functions incompensating the phosphate uptake in yeast MB192 mutantthat is defective in phosphate transport under Pi deficiency. RT-qPCR showed that the SlMPT3;1 is expressed in all oftomato tissues, but highly accumulated in the young leavesand stems under Pi deficiency. The data demonstrated that atleast two copies of the SlMPT3;1 gene are inserted into therice genome, and the transcripts of the SlMPT3;1 mRNA arehighly accumulated in the roots of the transgenic rice. Theoverexpression of the SlMPT3;1 gene not only promotesphosphate uptake by the roots, but also increases thetranslocation of phosphate from the roots to the shoots in thetransgenic rice. The transgenic rice accumulated morechlorophyll and soluble sugar in the shoots than the wildtype under Pi deficiency. Microassay sequencing showedthat the differentially expressed genes in the transgenic riceare mainly involved in the regulations of biological processand molecular function under Pi deficiency. Further RTqPCRanalyses revealed that the differentially expressedgenes, which are involved in the regulations of the biologicalprocess, cell component, and molecular function, are upregulatedunder Pi deficiency, and exhibit similar expressiontrends to the relative expression folds of these partial differentiallyexpressed genes in the transcriptomic analyses. This studysuggests that the overexpression of the SlMPT3;1 gene promotedthe uptake and transport of phosphate in rice, thus leading to anenhanced increase in tiller number and effective panicle of perplant, and increasing grain yield under Pi deficiency.
Guo Xian,Muralimohan Cheepu,Jieun Yu,Sang Myung Cho,Jong‑Taek Yeom,Yoon Suk Choi,Namhyun Kang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.2
The cooling time of cryogenic vaporised Ar shielding/cooling of Ti-6Al-4 V deposits was ~ 10 times faster than that ofnormal Ar gas shielding/cooling. The columnar β grains in rapid cooling condition were observed to be in the longitudinaldirection of the deposits same as that in natural cooling condition. Under the rapid cooling, a narrow heat-affected zone band(~ 70 μm) and a wide vanadium-segregation band was observed, along with a reduced aspect ratio of the α plate, which ledto improved isotropic-tensile properties along the deposition and building directions. Rapid cooling condition also retaineda significant amount of O and N, which enhanced its hardness and tensile strength. Thus, cryogenic vaporised Ar shielding/cooling can produce Ti-6Al-4 V wire-arc additive manufacturing deposits with better tensile properties compared to normalAr gas shielding.