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排序方式: 共有9890条查询结果,搜索用时 15 毫秒
1.
L.J. Espinoza-Pérez S. Esquivel-Medina E. López-Honorato 《Ceramics International》2021,47(11):15527-15532
The influence of the microstructure on the corrosion rate of three monolithic SiC samples in FLiNaK salt at 900 °C for 250 h was studied. The SiC samples, labeled as SiC-1, SiC-2, and SiC-3, had corrosion rates of 0.137, 0.020, and 0.043 mg/cm2h, respectively. Compared with grain size and the presence of special grain boundaries (i.e., Σ3), the content of high-angle grain boundaries (HAGBs) appeared to have the strongest influence on the corrosion rate of SiC in FLiNaK salt, since the corrosion rate increased six times as the concentration of high-angle grain boundaries increased from 19 to 32% for SiC-2 and SiC-1, respectively. These results stress the importance of controlling the content of HAGBs during the production process of SiC. 相似文献
2.
Job rotation is defined as workers rotating between tasks with different exposure levels and occupational demands. The aim of the present study was to analyze the risk factors for the development of upper-limb work-related musculoskeletal disorders (UL-WMSDs) in poultry slaughterhouse workers as well as compare the score of the OCRA Checklist in different organizational working conditions. In this cross-sectional study, 118 workers were involved, 68 women (32.3 ± 10.7 years) and 50 men (29.5 ± 10.5 years). Three organizational configurations (“without job rotation”, “with job rotation – tasks >1h” and “with job rotation - tasks <1h”) were evaluated using the OCRA Checklist method, totaling 36 tasks and 28 job rotation schemes composed of 2–3 tasks. The OCRA score of the right upper limbs (17.8 ± 3.2) was significantly higher (p = 0.046) relative to the left upper limbs (16.4 ± 3.6). The median score was significantly lower in the “with job rotation - tasks <1h” condition (18.6) when compared to the “job rotation – tasks >1h” (19.4) (p < 0.001) and the “without job rotation” (19.0) (p = 0.038) conditions. However, there was no significant difference between the condition “with job rotation - tasks >1h” and “without job rotation” (p = 0.155). Thus, job rotations with intervals <1h reduced the risk of developing UL-WMSDs. Job rotations with <1 h intervals in poultry slaughterhouses are recommended along with further studies to verify the effectiveness of rotations with more than two tasks, involving mild or non-repetitive tasks. 相似文献
3.
Specialized varieties of sugar beets (Beta vulgaris L.) may be an eligible feedstock for advanced biofuel designation under the USA Energy Independence and Security Act of 2007. These non-food industrial beets could double ethanol production per hectare compared to alternative feedstocks. A mixed-integer mathematical programming model was constructed to determine the breakeven price of ethanol produced from industrial beets, and to determine the optimal size and biorefinery location. The model, based on limited field data, evaluates Southern Plains beet production in a 3-year crop rotation, and beet harvest, transportation, and processing. The optimal strategy depends critically on several assumptions including a just-in-time harvest and delivery system that remains to be tested in field trials. Based on a wet beet to ethanol conversion rate of 110 dm3 Mg−1 and capital cost of 128 M$ for a 152 dam3 y−1 biorefinery, the estimated breakeven ethanol price was 507 $ m−3. The average breakeven production cost of corn (Zea mays L.) grain ethanol ranged from 430 to 552 $ m−3 based on average net corn feedstock cost of 254 and 396 $ m−3 in 2014 and 2013, respectively. The estimated net beet ethanol delivered cost of 207 $ m−3 was lower than the average net corn feedstock cost of 254–396$ m−3 in 2013 and 2014. If for a mature industry, the cost to process beets was equal to the cost to process corn, the beet breakeven ethanol price would be $387 m-3 (587 $ m−3 gasoline equivalent). 相似文献
4.
《Journal of the European Ceramic Society》2022,42(1):112-118
Improving piezoelectric performance is always favorable to further enhance the sensitivity and accuracy of piezoelectric devices. Here, a complex piezoelectric system of Pb(Ni1/3Nb2/3)O3-Pb(Yb1/2Nb1/2)O3-Pb(Hf0.1Ti0.9)O3 is designed and investigated in detail. Optimized piezoelectric response of ~ 880 pC/N is achieved at the composition of 0.51PNN-0.09PYN-0.40PHT. The characterization of TEM and In-situ high-energy synchrotron diffraction indicate that nanodomain growth and microdomain switching occurs in succession at around coercive electric field. Most interestingly, the coexisted tetragonal and rhombohedral-like phase transforms into multiple monoclinic-like phases with polarization vectors aligned as close to the electric field direction as possible under the strong electric field. The enhanced polarization instability in this complex morphotropic phase boundary sample should be ascribed to the strong local heterogeneity. The novel polarization rotation behavior found in this work would be important guidance for designing high-performance piezoceramics. 相似文献
5.
A novel dual-rotation bobbin tool friction stir welding (DBT-FSW) was developed, in which the upper shoulder (US) and lower shoulder (LS) have different rotational speeds. This process was tried to weld 3.2 mm thick aluminum-lithium alloy sheets. The metallographic analysis and torque measurement were carried out to characterize the weld formability. Experimental results show that compared to conventional bobbin tool friction stir welding, the DBT-FSW has an excellent process stability, and can produce the defect-free joints in a wider range of welding parameters. These can be attributed to the significant improvement of material flow caused by the formation of a staggered layer structure and the unbalanced force between the US and LS during the DBT-FSW process. 相似文献
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该文针对当前电子白板系统对个性化支持的不足,引入手写笔作为输入设备,充分利用其功能参数,设计开发了具有模拟毛笔、钢笔、铅笔等真实笔特征的多笔型功能的电子白板系统。 相似文献
9.
聚硅烷的电子特性及非线性光学材料 总被引:3,自引:0,他引:3
综述了聚硅烷的电子结构、光吸收特性。重点介绍了聚硅烷在非线性光学材料中的研究与应用。 相似文献
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