| 1. |
- Wang, Yuanji, et al.
(författare)
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The diversity of microbial community and function varied in response to different agricultural residues composting
- 2020
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Ingår i: Science of the Total Environment. - : Elsevier B.V.. - 0048-9697 .- 1879-1026. ; 715
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Tidskriftsartikel (refereegranskat)abstract
- Microbial activities are the dynamic core in the soil nutrient cycle. To improve the knowledges about the responses of soil microbial community structure and potential function to long-term cover crops practice. The co-occurrence patterns of soil microbial community structure and functional genes were evaluated using 16SrRNA, ITS and metagenomic technique in 13 years cover crops of orchard grass (OG, Dactylis glomerata L.) with high C/N and white clover (WC, Trifolium repens L.) with low C/N. Conventional tillage (CT) was control. The experiment was implemented in an apple orchard located on the Loess Plateau, China, from 2006 to 2018. We also measured soil physicochemical properties and enzyme activities related to carbon and nitrogen cycling. The conclusions showed that the dominant bacterial phyla were Actinobacteria 27.68% in OG treatment and Proteobacteria 25.89% in WC treatment. Organic matter inputs stimulated growth of the phyla of Actinobacteria, Firmicutes, Chloroflexi, Ascomycota and genera of Bacillus, Blastococcus, Streptomyces and Penicillium. Interestingly, the OG and WC treatments promoted the fungal and bacterial alpha-diversity compared to CT treatment, respectively. In addition, compared to CT treatment, OG treatment was beneficial to the increase of C-cycle enzyme activity, while WC treatment tended to increase the N-cycle enzyme activity. Notably, compared to CT treatment, they both enriched carbon fixation and cycle pathways genes, while WC treatment increased the nitrogen metabolism pathway genes. Moreover, OG treatment was more conducive to the enrichment of carbohydrate enzymes genes involved in the hydrolysis of cellulose and hemicellulose compared to WC treatment. Overall, different quality of plant residues stimulated the specific expressions of soil microbial community structure and function. Long-term planted white clover was effective strategy to improve soil quality. © 2020 Elsevier B.V.
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| 2. |
- Huang, Xinyu, et al.
(författare)
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Investigation and optimization on melting performance of a triplex-tube heat storage tank by rotational mechanism
- 2023
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 205
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Tidskriftsartikel (refereegranskat)abstract
- Phase change heat storage is the backbone of energy storage technology, but its storage time is affected by the low thermal conductivity of phase change materials. Therefore, the melting performance of a triplex-tube latent heat thermal energy storage unit (T-LHTESU) in a phase change heat storage system is studied in this paper, and the rotation mechanism is applied to the unit. Firstly, a numerical model of the T-LHTESU considering the rotation mechanism is constructed, and the validity of the rotation unit is verified by comparison with experimental data. In this unit, N-eicosane is used as a phase change material for heat exchange. The effects of different rotational speeds on the liquid phase distribution, temperature distribution, flow velocity distribution, total energy storage, and energy storage efficiency of the T-LHTESU are studied. The results show that the melting time of this unit at 0.1 and 1 rpm is 46.98 and 69.35% lower than that of the stationary model, respectively. The total amount of stored heat is decreased by 0.67 and 2.17%, and the heat storage efficiency is increased by 87.34% and 219.19%, respectively. This indicates that the addition of the rotation mechanism greatly increases the heat storage efficiency of the T-LHTESU and reduces its total melting time, while the reduction of the total energy stored in the melting cycle is small. Then it is proved that rotation improves the single heat transfer mechanism of the stationary model and eliminates the thermal deposition caused by natural convection by studying the internal temperature/velocity response of the stationary model and the speed of 0.1 rpm. The related geometric structure of the model is optimized by response surface optimization design based on 0.1 rpm rotation speed. The influence of each variable on the target response is obtained, and compared with the original model, the melting time of the optimized model is reduced by 12.24%. Finally, based on the geometric optimization design, the influence of element physical factors (temperature and material of fin/tube wall) on the related melting properties is studied. This study is helpful to promote the effective use of rotation mechanism in phase change heat storage systems and has a certain guiding role in the structural design.
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| 3. |
- Huang, Xinyu, et al.
(författare)
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Optimization of melting performance of a heat storage tank under rotation conditions : Based on taguchi design and response surface method
- 2023
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Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 271
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Tidskriftsartikel (refereegranskat)abstract
- The melting performance of a rotating triplex-tube latent heat thermal energy storage unit is studied by numerical simulation method. The Taguchi design and response surface method are applied to its optimized design. Firstly, the Taguchi design method is used to quantitatively reveal the specific effects of fin distribution, fin number, and fin material on the melting performance of the unit. Compared with all-inner tube-fin or all-outer tube-fin structures, the melting time of alternating inside and outside fin structures is shortened by 52.64% and 32.42%, the average heat absorption rate is greatly increased by 105.56% and 47.26%, and the total heat is reduced by 2.64% and 2.17%, respectively. Then, the response surface method is applied to the eight alternating fins obtained by the Taguchi design, and the effects of fin length, width, and rotation angle on the melting time and average heat absorption rate of the unit are studied. Compared with the original structure, the optimal structure reduces the total melting time by 7.37% and increases the average heat absorption rate by 7.23%. The geometric parameters’ interaction with the relevant target response is studied, and the corresponding fluid-structure interaction equation is fitted. Finally, the melt growth phenomenon near the wall is found in the initial melting stage of the optimized model by mechanism analysis.
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| 4. |
- Li, Fangfei, et al.
(författare)
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Application and analysis of flip mechanism in the melting process of a triplex-tube latent heat energy storage unit
- 2023
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Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 9, s. 3989-4004
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Tidskriftsartikel (refereegranskat)abstract
- In order to improve the characteristics of uneven melting in the melting process of the horizontal latent heat energy storage system, the triplex-tube latent heat energy storage unit is taken as the research object, and the flip mechanism is applied to its melting process. Numerical simulation is used for the research, and the numerical model is verified by experimental data. The results show that under different dimensionless times, the melting performance of the unit can be significantly improved by a single flip. When the dimensionless time is 0.4576, it is found that the total melting time of the unit is reduced by 16.17 %, the average heat absorption rate is increased by 14.7 %, but the total heat energy absorption is reduced by 3.85 %. The results show that the addition of a flip can effectively shorten the melting time and increase the heat absorption rate, but it has a negative effect on the total heat absorption in one melting cycle. Moreover, through the comparison of dynamic flow rate, dynamic temperature response, and temperature interval, it is shown that the addition of flip effectively reduces the negative influence of the hard-to-melt zone on the melting performance of the unit during the melting process. The flip mechanism reduces the proportion of high-temperature phase change material in the melting process and makes the melting process more uniform.
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| 5. |
- Guo, Junfei, et al.
(författare)
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Thermal energy storage characteristics of finned tubes with different gradients of fin heights
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Ingår i: Numerical Heat Transfer; Part A: Applications. - 1040-7782.
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Tidskriftsartikel (refereegranskat)abstract
- Adding fins is considered to be a promising method to enhance heat transfer. As for the vertical latent thermal storage tube, it can be observed that the phase change materials in the upper part have much shorter charging time than in the lower part. To further enhance the heat transfer to boost the overall energy storage efficiency and reduce the apparent inhomogeneity of melting characteristics, fins with gradient height are packed. In this study, vertical shell-and-tube thermal energy storage tubes with fins of positive and negative gradient height are analyzed. After using experiments to verify the established numerical model, the phenomenological thermal characteristics are revealed and then additional analysis is used to investigate the thermal characteristics of the charging process, including melting, temperature distributions, and flow features. Results show that the negative gradient fins perform better than the positive gradient fins compared to the uniform ones. Furthermore, the complete melting time is reduced by 32.47% with a measured gradient of −0.8. A 42.11% enhancement in the time-integral average proportion of phase change materials (PCMs) in medium-temperature and a 78.74% suppression in the ratio of overheated PCMs at the final moment are achieved by the negative finned tube of −0.8 compared to a case with uniform fins. A tube with a higher bottom fin has a higher transient maximum velocity of the liquid phase transition material during melting, which also has a time-integral Grashof number (Gr) improvement of 31.46% compared to a uniform fin. The average energy storage is improved by using the negative gradient height fins of −0.8, as much as 1.34 times that of uniform height fins.
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| 6. |
- Li, Yuanji, et al.
(författare)
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Effect of pore density and filling ratio of metal foam on melting performance in a heat storage tank
- 2023
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Ingår i: Numerical Heat Transfer; Part A: Applications. - 1040-7782.
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Tidskriftsartikel (refereegranskat)abstract
- Thermal energy storage through solid–liquid phase change is an efficient method for mitigating solar energy intermittency by providing continuous energy supply for the end-users. However, the low thermal conductivity of phase change material, which serves as the heat transfer medium in the thermal energy storage systems, severely undermines the heat charging/discharging rates. Metal foam can significantly strengthen the heat storage performance via increasing the thermal conduction capability of phase change material and metal foam composite, mainly due to the large extension surface area and highly-conducting metallic ligaments of the metal foam. To squarely explore the influence of the two vital parameters (filling ratio and pore density) for the metal foam upon the phase change process, numerical models for describing the phase change process in a tank filled with phase change material and metal foam are established, and the experimental validations of the corresponding models are performed. Melting time, temperature uniformity, and heat storage capacity are selected as the targeted indexes for assessing and evaluating the impacts of filling ratio and pore density on the phase change process. The results show that the full melting time of heat storage decreases first and then increases with the decrease of filling ratio under any PPI. The smaller the PPI, the smaller the overall heat storage time. And the larger the PPI, the greater effect of the filling ratio on the heat storage time. The melting time of the PCM under the optimal filling ratio of 10 PPI and 100 PPI is shortened by 8.06% and 18.06%, and the temperature uniformity is reduced by 5.48% and 10.11%, respectively, compared with that of the complete filling.
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| 7. |
- Li, Yuanji, et al.
(författare)
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Experimental and numerical investigations on tilt filling design of metal foam in a heat storage tank
- 2023
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Ingår i: Renewable energy. - 0960-1481 .- 1879-0682. ; 217
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Tidskriftsartikel (refereegranskat)abstract
- The use of metal foam as a filler in heat storage tanks proves advantageous in compensating for the low thermal conductivity of phase change materials. However, the filling of metal foam can impede natural convection within the tank. Partially filled metal foam enables both strong natural convection in the upper pure phase change material region and enhanced thermal conductivity of the metal foam. This paper proposes inclining the upper surface of the metal foam to further strengthen natural convection in the upper region. Following experimental verification, a series of heat storage tanks with different metal foam inclination forms for latent heat storage were numerically simulated and compared. The results indicate that complete melting time was shortest for the case 5 (ab-type model with a = 0, b = 91.8), at 5320s, which represents an 18.8% reduction compared to benchmark case 9. Furthermore, comparison of the cases with inclined upper surfaces indicated that the clockwise inclination pattern resulted in greater time savings than the counterclockwise pattern. The results of this study offer valuable insights for the design of partially filled heat storage tanks.
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| 8. |
- Wang, Sen, et al.
(författare)
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ATAC-seq reveals the roles of chromatin accessibility in the chondrocytes of Kashin-Beck disease compared with primary osteoarthritis
- 2023
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Ingår i: Frontiers in Genetics. - : Frontiers Media S.A.. - 1664-8021. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study aimed to investigate the roles of accessible chromatin in understanding the different pathogeneses between Kashin-Beck disease (KBD) and primary osteoarthritis (OA).Methods: Articular cartilages of KBD and OA patients were collected, and after tissue digestion, primary chondrocytes were cultured in vitro. Assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) was performed to compare the accessible chromatin differences of chondrocytes between KBD and OA groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were executed for the promoter genes. Then, the IntAct online database was used to generate networks of significant genes. Finally, we overlapped the analysis of differentially accessible region (DAR)-associated genes and differentially expressed genes (DEGs) obtained from whole-genomic microarray.Results: We obtained 2,751 total DARs, which contained 1,985 loss and 856 gain DARs and belonged to 11 location distributions. We obtained 218 motifs associated with loss DARs, 71 motifs associated with gain DARs, 30 motif enrichments of loss DARs, and 30 motif enrichments of gain DARs. In total, 1,749 genes are associated with loss DARs, and 826 genes are associated with gain DARs. Among them, 210 promoter genes are associated with loss DARs, and 112 promoter genes are associated with gain DARs. We obtained 15 terms of GO enrichment and 5 terms of KEGG pathway enrichment from loss DAR promoter genes, and 15 terms of GO enrichment and 3 terms of KEGG pathway enrichment from gain DAR promoter genes. We obtained CAPN6 and other 2 overlap genes from loss DARs-vs-down DEGs, AMOTL1 from gain DARs-vs-down DEGs, EBF3 and other 12 overlap genes from loss DARs-vs-up DEGs, and ADARB1 and other 10 overlap genes from 101 gain DARs-vs-up DEGs. These overlap genes were built into 4 gene interaction networks.Conclusion: FGF7, GPD1L, NFIB, RUNX2, and VCAM1 were the overlapped genes from the DAR-associated genes and DEGs. These genes were associated with the abnormal chondrocyte function, which may play crucial roles in different processes between KBD and OA in the way of accessible chromatin.
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| 9. |
- Yang, Xiuxiang, et al.
(författare)
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Global Stability Analysis on the Dynamics of an SIQ Model with Nonlinear Incidence Rate
- 2012
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Ingår i: Advances in Future Computer and Control Systems;2. - Berlin, Heidelberg : Springer. - 9783642293894 - 9783642293900 ; , s. 561-566
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Konferensbidrag (refereegranskat)abstract
- An SIQ epidemic model with isolation and nonlinear incidence rate is studied. We have obtained a threshold value R and shown that there is only a disease free equilibrium point when R < 1, and there is also an endemic equilibrium point if R > 1. With the help of Liapunov function, we have shown that disease free- and endemic equilibrium point is globally stable.
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