PRECIPITATION IN A Cu-BASED SMA

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Amine Coordinated Electron-Rich Palladium Nanoparticles for Electrochemical Hydrogenation of Benzaldehyde

Electrocatalytic hydrogenation (ECH) is a burgeoning strategy for the sustainable utilization of hydrogen. However, how to effectively suppress the competitive hydrogen evolution reaction (HER) is a big challenge to ECH catalysis. In this study, amine (NH₂ R)-coordinated Pd nanoparticles loaded on carbon felt (Pd@CF) as a catalyst is successfully synthesized by a one-step solvothermal reduction method using oleylamine as the reducing agent. An exceptional ECH reactivity on benzaldehyde is achieved on the optimal Pd@CF catalyst in terms of a high conversion (89.7%) and selectivity toward benzyl alcohol (89.8%) at −0.4 V in 60 min. Notably, the Faradaic efficiency for producing benzyl alcohol is up to 90.2%, much higher than that catalyzed by Pd@CF-without N-group (41.1%) and thecommercial Pd/C (20.9%). The excellent ECH performance of Pd@CF can be attributed to the enriched electrons on Pd surface resulted from the introduction of NH₂ R groups, which strengthens both the adsorption of benzaldehyde and the adsorbed hydrogen (H_ads) on Pd, preventing the combination of H_ads to form H₂, that is, inhibiting the HER. This study gives a new insight into design principles of highly efficient electrocatalysts for the hydrogenation of unsaturated aldehydes molecules.     

Opportunistic channel selection approach under collision probability constraint in cognitive radio systems

In this work, we consider a cognitive radio system with multiple primary channels and one secondary user, and then we introduce a channel-usage pattern model and some basic concepts in this system. Based on this system model and the basic concepts, we propose two opportunistic channel selection algorithms to optimize the throughput of the secondary user: minimum collision rate channel selection algorithm and minimum handoff rate channel selection algorithm. According to the two algorithms, we, respectively, present the channel selection scheme based on minimum collision rate algorithm (CSS-MCRA) and the channel selection scheme based on minimum handoff rate algorithm (CSS-MHRA) under the constraint that the collision probability is bounded below collision tolerable level. Theoretical analysis and simulation results both show that, on one hand, both CSS-MCRA scheme and CSS-MHRA can follow the constraint of collision tolerable level; on the other hand, the performance of CSS-MCRA scheme is better than that of CSS-MHRA scheme if handoff latency is zero or very low, while the performance of CSS-MHRA scheme is better than that of CSS-MCRA scheme if handoff latency is long enough.     

发展超超临界发电机组若干技术问题探讨

总结国外超临界和超超临界机组的发展现状及趋势，探讨超超临界机组技术选型的若干问题，提出了我国发展超超临界机组的发展思路。     

金川龙首混合矿选矿降镁工艺研究与实践

对金川镍矿龙首矿混合矿石进行了降镁工艺小型试验和验证试验。对选矿车间２＃ 、１＃ 系统进行了流程改造。工业试验及生产实践结果表明：精矿中氧化镁从１０％ 左右降至７％ 以下。     

果胶超滤纯化过程传质模型和动力学分析

研究了果胶提取液超滤膜分离处理过程传质特征,建立了渗透通量、膜面浓度与压差的传质模型,并对膜阻力和浓差极化阻力进行了定量描述;同时对超滤过程的动力学进行了分析.     

音素关联的多文种语音融合编码方法

依据异类文种之间、同类文种不同语音之间存在音素数据关联的特性,提出多文种语音数据融合编码方法。将不同文种存在的相同音素数据段块按段块模板截取语音样本序列,小波变换,提取特征矢量,生成共享模板集;任意字音或语句音串均按共享模板集提供的元素进行编码与解码;以模板音素串构成的语音记录库按（音节、音素）索引。实验结果表明,单字语音数据压缩比、语音数据存储量、语音还原分段信噪比、主观评价得分等参数均明显优于已有方法,语音还原质量良好。     

600MW超临界汽轮机高压加热器泄漏原因分析及处理

某电厂2号600MW超临界机组在商业运行2年后,3号高压加热器出现了管系泄漏.分析了造成3号高压加热器漏泄的各种因素,指出了管系的高温腐蚀和热冲击是造成高压加热器漏泄的主要原因.对此,从运行中的监视维护、高压加热器启停的操作等方面提出了针对性的解决方案和预防措施,对泄漏管进行了封堵及严控水质和正确的启停操作以防较大的热冲击并建议更换耐高温管.有效地防止了漏管的蔓延,确保了高压加热器的安全稳定及经济运行.     

降雨条件下纤维浅层固坡机制试验研究

植被根系大多分布在土体浅表层,在渗流作用下能有效防止浅层滑坡和地表侵蚀。研究采用人工合成纤维加筋土模拟植被的根系作用防治边坡渗流失稳破坏。为探究聚丙烯纤维的长度对土体强度的影响以及纤维加筋边坡在渗流作用下的稳定性,制备的加筋粉砂分别参入不同含量（0.25%,0.50%）和长度（6 mm、12 mm）的聚丙烯纤维。通过室内三轴固结排水试验研究加筋粉砂的基本性质,并开展了素土边坡和加筋边坡在人工降雨条件下的室内模型试验。其中,仅对边坡的浅表层进行加筋处理。研究表明,加筋粉砂的抗剪强度和粘聚力相比普通粉砂得到明显提高,而加筋前后粉砂内摩擦角变化不大。相比于素土边坡,随着纤维长度的增加,加筋边坡的破坏速度变缓、破坏程度得到明显改善,边坡破坏由全坡破坏到坡面局部破坏再到无明显性破坏的模式。     

舰船尾轴承变形对其阻尼特性的影响研究

舰船推进轴系受多个载荷的作用,导致船体、螺旋桨轴和尾轴承发生变形,并在尾轴承中心线与螺旋桨轴颈中心线之间形成一个变形角。研究了变形夹角对轴承油膜动态阻尼参数的影响关系,用数值计算的方法计算得到了轴承油膜阻尼参数与变形角之间的变化关系。结果表明：轴承中线与轴颈轴线之间的变形夹角对轴承润滑阻尼参数的影响关系为强的非线性关系;变形角对轴承阻尼特性影响较大,随着变形角的增大,油膜阻尼Dxx和Dyy会增大,而阻尼Dyz和Dxy会减小;轴颈中线与轴承中线之间夹角对油膜阻尼参数的影响局限在一定的弯曲变形范围内,当变形继续增大时,螺旋桨轴与尾轴承发生刚性接触,此时轴与轴承的刚性接触摩擦作用增大,阻尼作用急剧改变。