| 11. |
- Zhang, Hongwei, et al.
(författare)
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Partial Equilibrium Prediction of Solidification and Carbide Precipitation in Ti-added High Cr Cast Irons
- 2014
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Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 54:2, s. 374-383
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Tidskriftsartikel (refereegranskat)abstract
- Carbide precipitation and eutectic phase transformation during solidification of Fe-C-Cr-Ti-Mn-Mo-Ni-Si Ti-added high-chromium cast irons (HCCIs) were studied numerically and experimentally by the help of Partial Equilibrium approximation, DSC thermal analyses and EDX analyses. The main carbides formed during the solidification are distinguished as MC, primary M7C3 and eutectic M7C3 from their distinguished constitution, while other researchers didn't distinguish the primary and eutectic M7C3 carbide. Through comparing the prediction of Partial Equilibrium approximation with DSC thermal analysis measurement, the precipitation sequence of the eutectic structure in HCCIs is clarified to follow the sequence of FCC prior to the eutectic M7C3, although they were usually expected to precipitate simultaneously. The hardness index of the HCCIs is evaluated quantatively by summation of the contributions of the Vickers hardness of MC, primary M7C3 and eutectic M7C3 carbides with predicted precipitation amount and composition / constitution. The effects of C, Ti and Cr contents on the precipitation sequence, the amount and the composition of carbides as well as the hardness of the HCCIs are discussed deeply. Finally, the validity of Partial Equilibrium approximation is shown in prediction of the solidification in multicomponent system with large amount of precipitated carbides.
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| 12. |
- Zhang, Qiang, et al.
(författare)
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Changes of atmospheric water vapor budget in the Pearl River basin and possible implications for hydrological cycle
- 2010
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 0177-798X .- 1434-4483. ; 102:1-2, s. 185-195
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we thoroughly analyzed abrupt behaviors, trends, and periodicity properties of water vapor flux and moisture budget entering and exiting the four edges of the Pearl River basin based on the NCAR/NCEP reanalysis dataset by using the continuous wavelet transform and the simple two-phase linear regression technique. Possible implications for hydrological cycle and water resource management of these changes are also discussed. The results indicate that: (1) the water vapor propagating through the four edges of the Pearl River basin is decreasing, and it is particularly true for the changes of the water vapor flux exiting from the north edge of the study river basin. The transition point from increase to decrease occurs in the early 1960s; (2) The wavelet transform spectra indicate that the monthly water vapor flux through the north edge decreases and this decrease is mainly reflected by intermittent distribution of the wavelet power spectra after early 1980s. The periodicity properties of the water vapor flux through the north edge imply that the northward propagation of water vapor flux decreases after the 1980s; (3) close relations between water vapor flux, precipitation and streamflow implies that the altered hydrological cycle in the Pearl River basin is mainly manifested by seasonal shifts of water vapor flux after early 1960s. One of the direct consequences of these changes of water vapor flux is the seasonal transition of wet and dry conditions across the Pearl River basin. Regional responses of hydrological cycle to climate variation/change could be different from one river basin to another. Hydrological responses of the Pearl River basin to the global warming are mainly demonstrated by seasonal shifts of precipitation changes: winter comes to be wetter and summer tends to be dryer. The finding of the seasonal transition of precipitation in the Pearl River basin is of great scientific and practical merits in basin scale water resource management in the Pearl River basin under the changing climate and global warming in particular.
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| 13. |
- Zhang, Qiang, et al.
(författare)
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Precipitation extremes in a karst region : a case study in the Guizhou province, southwest China
- 2010
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 0177-798X .- 1434-4483. ; 101:1-2, s. 53-65
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Tidskriftsartikel (refereegranskat)abstract
- We analyzed the changing properties of precipitation extremes in the Guizhou province, a region of typical karst geomorphology in China. Precipitation extremes were defined by the largest 1- and 5-day precipitation total. Trends of precipitation extremes were detected by using Mann-Kendall trend test technique. Besides, we also investigated moisture flux variations based on the National Centers for Environmental Prediction and the National Center for Atmospheric Research reanalysis dataset with the aim to further explore the possible causes behind the changes in precipitation extremes. The results of this study indicated that: (1) Although the changes in precipitation extremes at most of the stations were not significant, enhanced precipitation extremes were still detected after the early 1990s mainly in the middle and west parts of the Guizhou province; (2) In winter, east and south parts of the Guizhou province were characterized by increasing precipitation extremes; In summer, enhanced precipitation extremes were observed mainly in the middle and east parts of the Guizhou province; (3) A significant increase of moisture flux was observed after the 1990s when compared to that before the 1990s. Cumulative departure analysis results of moisture flux and precipitation extremes confirmed the influences of moisture flux on the variations of precipitation extremes in the study region. This study clarified the changes of weather extremes and their linkages with large-scale atmospheric circulation in the karst region of China, which will definitely enhance human mitigation to natural hazards in the fragile ecological environment under the influences of changing climate.
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| 14. |
- Zhang, Zhi-qiang, et al.
(författare)
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Effect of fault on tunnel stability with different distribution
- 2013
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Ingår i: Global View of Engineering Geology and the Environment. - London : CRC Press, Taylor & Francis Group. - 9781138000780 ; , s. 279-285
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Konferensbidrag (refereegranskat)abstract
- For tunnel engineering, the fault that locates near tunnel always plays an important role on the stability of the surrounding rock mass and the safety of the supporting system. To investigate the influence of the fault on the tunnel stability, systematic numerical experiments are carried out via the FINAL code. Through these numerical experiment results, the displacement and the distribution of the stress in surrounding rock mass are analyzed for these cases of the different locations and dips of fault around tunnel periphery, and the stress in the sprayed concrete layer are analyzed as well. To simulate the characteristics of the fault located in the rock mass, the COJO element, embedded in the FINAL code, is used in all numerical experiments. The quantized results reflecting the rules of the change for the displacement, stress, plastic region in the surrounding rock mass are obtained also in this paper.
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| 15. |
- Zhu, Yaobin, et al.
(författare)
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A novel, minimally invasive rat model of normothermic cardiopulmonary bypass model without blood priming.
- 2014
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Ingår i: Chinese Medical Journal. - 0366-6999. ; 127:8, s. 1541-1544
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Tidskriftsartikel (refereegranskat)abstract
- Cardiopulmonary bypass (CPB) has been shown to be associated with systemic inflammatory response leading to postoperative organ dysfunction. Elucidating the underlying mechanisms and developing protective strategies for the pathophysiological consequences of CPB have been hampered due to the absence of a satisfactory recovery animal model. The purpose of this study was to establish a novel, minimally invasive rat model of normothermic CPB model without blood priming.
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| 16. |
- Chen, David, et al.
(författare)
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Hydrologic alteration along the Middle and Upper East River (Dongjiang) basin, South China : a visually enhanced mining on the results of RVA method
- 2010
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Ingår i: Stochastic environmental research and risk assessment (Print). - : Springer Science and Business Media LLC. - 1436-3240 .- 1436-3259. ; 24, s. 9-18
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a visually enhanced evaluation of the spatio-temporal patterns of the dam-induced hydrologic alteration in the middle and upper East River, south China over 1952-2002, using the range of variability approach (RVA) and visualization package XmdvTool. The impacts of climate variability on hydrological processes have been removed for wet and dry periods, respectively, so that we focus on the impacts of human activities (i.e., dam construction). The results indicate that: (1) along the East River, dams have greatly altered the natural flow regime, range condition and spatial variability; (2) six most remarkable indicators of hydrologic alteration induced by dam-construction are rise rate (1.16), 3-day maximum (0.91), low pulse duration (0.88), January (0.80), July (0.80) and February (0.79) mean flow of the East River during 1952-2002; and (3) spatiotemporal hydrologic alterations are different among three stations along Easter River. Under the influence of dam construction in the upstream, the degree of hydrologic changes from Lingxia, Heyuan to Longchuan station increases. This study reveals that visualization techniques for high-dimensional hydrological datasets together with RVA are beneficial for detecting spatio-temporal hydrologic changes.
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| 17. |
- Chen, Xu-Guang, et al.
(författare)
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Analogical model test and theoretical analysis on zonal disintegration based on filed monitoring in deep tunnel
- 2013
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Ingår i: European Journal of Environmental and Civil Engineering. - : Informa UK Limited. - 1964-8189 .- 2116-7214. ; 17:Suppl. 1, s. 33-52
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Tidskriftsartikel (refereegranskat)abstract
- Field monitoring carried out in a deep tunnel of the Dingji coal mine in China confirmed the zonal disintegration phenomenon by using the borehole TV. Based on field monitoring, an analogical model test was conducted to research the fracture shape and forming conditions of the rock mass in the Dingji mine. To perform the model test, an analogical material and optical sensor were developed independently. Through the test, the occurrence of zonal disintegration was confirmed and the forming process was monitored. The fracture pattern of zonal disintegration was determined, and the radii of the fractured zones were found to fulfil the relationship of geometric progression. The displacement laws of surrounding rocks during zonal disintegration were obtained and found to be non-monotonic. The test results are in agreement with the field-monitoring results. Through a theory analysis based on fracture mechanics, the mechanism of zonal disintegration was revealed. The fracture zones occur as circles concentric to the cavern periphery, which is the “false face”. Each fracture zone ruptures at the elastic–plastic boundary of surrounding rocks and then coalesces into a circle. The geometric progression ratio was determined; it is related to the mechanical parameters and ground stress of the surrounding rocks and calculated as follows: And the mechanism of the non-monotonic displacement law is revealed; the continuous formation of the “false face” causes the geostress redistribution and crack opening.
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| 18. |
- Duan, Chen, et al.
(författare)
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Comparative analysis of gene expression profiles between primary knee osteoarthritis and an osteoarthritis endemic to Northwestern China, Kashin-Beck disease.
- 2010
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Ingår i: Arthritis and Rheumatism. - : John Wiley & Sons. - 0004-3591 .- 1529-0131. ; 62:3, s. 771-780
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the differences in gene expression profiles of adult articular cartilage from patients with Kashin-Beck disease (KBD) versus those with primary knee osteoarthritis (OA).METHODS: The messenger RNA expression profiles of articular cartilage from patients with KBD, diagnosed according to the clinical criteria for KBD in China, were compared with those of cartilage from patients with OA, diagnosed according to the Western Ontario and McMaster Universities OA Index. Total RNA was isolated separately from 4 pairs of the KBD and OA cartilage samples, and the expression profiles were evaluated by Agilent 4x44k Whole Human Genome density oligonucleotide microarray analysis. The microarray data for selected transcripts were confirmed by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) amplification.RESULTS: For 1.2 x 10(4) transcripts, corresponding to 58.4% of the expressed transcripts, 2-fold changes in differential expression were revealed. Expression levels higher in KBD than in OA samples were observed in a mean + or - SD 6,439 + or - 1,041 (14.6 + or - 2.4%) of the transcripts, and expression levels were lower in KBD than in OA samples in 6,147 + or - 1,222 (14.2 + or - 2.8%) of the transcripts. After application of the selection criteria, 1.85% of the differentially expressed genes (P < 0.001 between groups) were detected. These included 233 genes, of which 195 (0.4%) were expressed at higher levels and 38 (0.08%) were expressed at lower levels in KBD than in OA cartilage. Comparisons of the quantitative RT-PCR data supported the validity of our microarray data.CONCLUSION: Differences between KBD and OA cartilage exhibited a similar pattern among all 4 of the pairs examined, indicating the presence of disease mechanisms, mainly chondrocyte matrix metabolism, cartilage degeneration, and apoptosis induction pathways, which contribute to cartilage destruction in KBD.
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| 19. |
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| 20. |
- Feng, Yi, et al.
(författare)
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Flexible UHF resistive humidity sensors based on carbon nanotubes
- 2012
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 12:9, s. 2844-2850
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the investigation of the resistive humidity-sensing properties of multi-walled carbon nanotubes (MWCNTs). MWCNTs functionalized by acid treatment (f-MWCNTs) exhibit rather high sensitivity in resistance toward humidity, owing to the presence of carboxylic groups on the nanotube surface. By integrating the f-MWCNTs resistor into a wireless sensor platform, flexible humidity sensors for ultra-high frequency applications are investigated. The operating frequency range of the sensor is dramatically increased from 600 MHz to 2 GHz by adjusting the resistor-electrodes' configuration. This enhancement is predominately attributed to the variation in parasitic capacitance between the resistor-electrodes.
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