| 1. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3– 19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8– 144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 2. |
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| 3. |
- He, Qing, et al.
(författare)
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Co-pyrolysis Behavior and Char Structure Evolution of Raw/Torrefied Rice Straw and Coal Blends
- 2018
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Ingår i: Energy & Fuels. - Washington : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 32:12, s. 12469-12476
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Tidskriftsartikel (refereegranskat)abstract
- Combination of biomass and coal for energy production is conducive to the sustainable development of society and a clean-energy future. This study investigates co-pyrolysis behavior of raw/torrefied rice straw and coal blends. Mild torrefaction (250 degrees C) and severe torrefaction (300 degrees C) were taken into consideration. Samples of five mixing ratios were tested by thermogravimetric analyzer, and the resulting chars were characterized by Raman spectroscopy and SEM-EDS. The results show that co-pyrolysis had little effect on char yields. Decomposition rate curves showed two distinct peaks for raw/mildtorrefied rice straw and coal blends, and the reaction rate was enhanced below 380 degrees C. However, only one peak appeared for severely torrefied rice straw blended with coal. During co-pyrolysis, the secondary pyrolysis of coal around 700 degrees C was inhibited, and the graphitization degree of biomass char increased, while the crystalline structure of coal char was poorly organized. The activation energy of mixtures also changed in different pyrolysis stages.
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| 4. |
- Li, Rongrong, et al.
(författare)
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Non-standard test method for glue line shear strength
- 2017
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Ingår i: Wood research. - : Statny Drevarsky Vyskumny Ustav. - 1336-4561. ; 62:5, s. 825-830
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Tidskriftsartikel (refereegranskat)abstract
- The relevant standards for glueline shear strength testing were summarized and analyzed in this paper. Depending on these existing test standards, the resulting stress in glueline is not pure shear stress, but a combination of shear and normal stresses. In order to overcome this deficiency, a symmetrical structure was proposed for making samples. Some comparative testing was accomplished by using these symmetrical samples, the results showed that the normal stress could be avoided during testing. These results were also confirmed by finite element method (FEM), the simulation results showed that the shear stress in glueline was uniform
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| 5. |
- Li, Rongrong, et al.
(författare)
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Prediction of cutting force during gypsum fiber composite milling process using response surface methodology
- 2017
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Ingår i: Wood and Fiber Science. - : Society of Wood Science and Technology. - 0735-6161. ; 49:4, s. 453-460
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Tidskriftsartikel (refereegranskat)abstract
- Gypsum fiber composite (GFC) is a kind of building material widely used in interior decoration. Milling is the most commonly used machining process for GFC. Cutting force as an important cutting characteristic parameter has significant influence on the quality of machined surface, power consumption, and tools wear. The tangential force (Fx) and normal force (Fy) were measured and analyzed to find out the effects of milling parameters on these cutting forces. Milling parameters considered were spindle speed, feed rate, and depth of cut. The response surface methodology (RSM) was selected to develop mathematical models and optimize milling parameters. The results showed that with the increase of feed rate and depth of cut, the Fx and Fy increased. But the cutting forces decreased with the increase of spindle speed. The optimization results indicated that high spindle speed, low feed rate, and small depth of cut are preferable for milling of GFC to obtain the best result.
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| 6. |
- Mu, Liwen, et al.
(författare)
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Grafting Heteroelement-Rich Groups on Graphene Oxide : Tuning Polarity and Molecular Interaction with Bio-Ionic Liquid for Enhanced Lubrication
- 2017
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 498, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- Two different heteroelement-rich molecules have been successfully grafted on graphene oxide (GO) sheets which were then used as lubricant additives in bio-ionic liquid. The grafting was processed with reactions between GO sheets and synthesized heteroelement-rich molecules (Imidazol-1-yl phosphonic dichloride and 1H-1,2,4-triazol-1-yl phosphonic dichloride, respectively). The modified GO (m-GO) was added into [Choline][Proline] ([CH][P]) bio-ionic liquid, and has been demonstrated effective additive in promoting lubrication. Different characterization techniques have been utilized to study the reaction between GO and the two modifiers. The effect of molecular structure of the modifiers on the rheological and tribological properties of m-GO/[CH][P] lubricants was systematically investigated. Both theoretical calculation and experimental results demonstrated that the introduced heteroelement-rich groups are beneficial to increase the robustness of lubrication film by intensified hydrogen bonding and enhance the lubricant/friction surface adhesion by increased polarity of the m-GO. As a result, the interfacial lubrication could be significantly improved by these newly developed m-GO/[CH][P] lubricants.
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| 7. |
- Wei, Hong, et al.
(författare)
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Analysis of Cutting Performance in High Density Fiberboard Milling by Ceramic Cutting Tools
- 2018
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Ingår i: Wood research. - : Slovak Forest Products Research. - 1336-4561. ; 63:3, s. 455-466
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Tidskriftsartikel (refereegranskat)abstract
- In order to study the cutting performance of TiC reinforced Al2O3 ceramic cutting tools in milling high density fiberboard, the effects of cutting parameter on the cutting forces, tool wear and cutting quality were investigated. Under the condition of same average chip thickness, feed per tooth and geometry angles, firstly, the change rate of maximum cutting forces were higher than that of average cutting forces at two different cutting speeds, and the cutting forces at high speed cutting was less than that at low speed cutting. Secondly, the flank wear at high speed cutting was more pronounced than that at low speed cutting, whose abnormal wear were pull-out of grain, cracking, chipping and flanking. Thirdly, the machining quality at high speed cutting was better than that at low speed cutting. Fourthly, the tendencies of cutting forces, tool wear and surface roughness relative to cutting length were similar, but the change rates were different, especially at the initial stage. Finally, high speed cuttingare plausible to use in HDF processing, which not only improves machining quality, but also promotes production efficiency.
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| 8. |
- Wei, Juntao, et al.
(författare)
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A mechanism investigation of synergy behaviour variations during blended char co-gasification of biomass and different rank coals
- 2018
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Ingår i: Renewable energy. - : Elsevier. - 0960-1481 .- 1879-0682. ; 131, s. 597-605
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Tidskriftsartikel (refereegranskat)abstract
- Co-gasification reactivity of rice straw and bituminous coal/anthracite blended chars under CO2 atmosphere was evaluated using thermogravimetric analysis, and the influences of coal type and gasification temperature on synergy behaviour variations on co-gasification reactivity as carbon conversions increased were quantitatively studied. Furthermore, the chemical forms and concentrations of AAEM species at different co-gasification conversions were quantitatively analyzed for revealing co-gasification synergy mechanism. The results demonstrate that as conversions increased, synergy behaviour on co-gasification reactivity of rice straw-bituminous coal blends was shown as the weakened inhibition effect firstly and then the enhanced synergistic effect. Moreover, the inhibition effect on co-gasification reactivity of rice straw-bituminous coal blends was sustained up to higher conversion with the increment of gasification temperature. Differing from rice straw-bituminous coal blends, synergistic effect on co-gasification reactivity of rice straw-anthracite blends was obviously enhanced at early stage of co-gasification and started to slowly weaken after reaching the most significant synergistic effect at middle stage of co-gasification. Additionally, it was revealed that synergy behaviour variations on co-gasification reactivity of rice straw-bituminous coal blends were mainly attributed to the combination effects of active K and Ca transformation during co-gasification, while those of rice straw-anthracite blends indicated a good correlation with active K transformation during co-gasification.
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| 9. |
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| 10. |
- Yu, Jun-Qin, et al.
(författare)
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Effect of biomass ash addition on gasification characteristics of anthracite char
- 2018
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Ingår i: Ranliao Huaxue Xuebao/Journal of Fuel Chemistry and Technology. - : Science Press. - 2097-213X .- 1872-5813. ; 46:10, s. 1161-1167
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Tidskriftsartikel (refereegranskat)abstract
- Zunyi anthracite was used as the raw material of gasification and rice straw ash and cotton stalk ash were optioned as biomass ash additives. Char-CO2 isothermal gasification experiments were conducted using TGA to investigate the effect of biomass ash addition on coal char gasification characteristics. Furthermore, the relationship between char structure evolution during gasification and char gasification reactivity was investigated. The results indicate that the biomass ash addition has a promotion effect on coal char gasification, which is well related to the increase in active AAEM content and the decrease in the order degree of carbon structure of chars by the addition of biomass ash. However, the promotion effect of biomass ash additives on coal char gasification is weakened with increasing gasification temperature, mainly due to that the positive effect of biomass ash additive on the increase of active AAEM content in char and the inhibition effect of biomass ash additive on carbon structure order degree of coal char become weaker at higher gasification temperature. Additionally, it is found that cotton stalk ash has a more significant positive effect on coal char gasification than rice straw ash because cotton stalk ash has a more obvious effect on the increase in active AAEM content and the decrease in the carbon structure graphitization degree of coal char.
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