一种改进的短时平均幅度差函数算法

在语音信号分析中,对于基音周期的提取目前已有较多的分析和处理方法,在现有的短时平均幅度差函数(AMDF)的处理方法中,只需要加、减和取绝对值运算,运算量较之短时自相关函数大大下降。同时,AMDF函数的谷点提取基音周期比自相关函数的峰值更加尖锐,错判率相对较少,稳健性更高。然而,传统的AMDF算法对窗长的要求较为严格,窗长较短就会有较大的误差。本文针对该缺陷做出的改进算法,使之无论窗长多大均会有较为准确的结果,大大拓展了AMDF算法的适用空间。进一步,将其与同态处理结合,会有更好的效果。     

燃烧型超高频热声斯特林发电机实验研究

几十至几百瓦级便携式发电设备在离网应用和应急救灾等场景发挥着重要作用。自由活塞斯特林热机因其外燃属性带来的燃料适应性好、高效、可靠和静音等突出优点而有望成为便携式电源系统的重要发电技术。本文首次提出柴油气化燃烧驱动超高频自由活塞斯特林发电机的便携式发电系统。基于热声学的阻抗匹配和燃烧–交变流动热耦合,设计并研制了一套实验系统,实验中系统考察了不同燃烧功率下的输出特性,并开展了损失分析。初步实验结果表明,该发电系统在加热温度约为600℃时的最大输出电功为320 W,以柴油热值计算的最高热电效率为11.28%。受益于130 Hz的超高工作频率,发电机本体的比功率为90 W/kg,展现出良好的应用潜力。     

1,3-二烷基咪唑离子液体-水二元混合物的溶致显色参数和优先溶剂化行为

Binary mixtures of 1,3-dialkylimidazolium based ionic liquids (ILs) and water were selected as solvent systems to investigate the solute-solvent and solvent-solvent interactions on the preferential solvation of solvatochromic indicators at 25℃. Empirical solvatochromic parameters, dipolarity/polarizability (π^*), hydrogen-bond donor acidity (α), hydrogen-bond acceptor basicity (β), and Reichardt''s polarity parameters (E_T^N) were measured from the ultraviolet-visible spectral shifts of 4-nitroaniline, 4-nitroanisole, and Reichardt''s dye. The solvent properties of the IL-water mixtures were found to be influenced by IL type and IL mole fraction (x_IL). All these studied systems showed the non-ideal behavior. The maximum deviation to ideality for the solvatochromic parameters can be obtained in the xIL range from 0.1 to 0.3. For most of the binary mixtures, the π^* values showed the synergistic effects instead of the E_T^N, α and β values. The observed synergy extent was dependent on the studied systems, such as the dye indicator and IL type. A preferential solvation model was utilized to gather information on the molecular interactions in the mixtures. The dye indicator was preferentially solvated on the following trend: IL >IL-water complex >water.     

静态腐蚀条件下铁素体/马氏体钢和奥氏体不锈钢与液态铅铋合金相容性研究进展

液态铅铋合金（LBE）是铅冷快中子反应堆（LFR）和加速器驱动次临界系统(ADS)的主要冷却剂材料。反应堆用结构材料（如铁素体/马氏体钢、奥氏体不锈钢等）在液态LBE环境下存在液态金属腐蚀（LMC）和应力腐蚀的问题,这些问题给钢结构材料的安全服役带来隐患。阐述了钢材铅铋腐蚀类型及机理,归纳了材料设计与处理(元素成分、热处理、加工制造和表面处理)和腐蚀条件（氧质量分数、腐蚀温度和腐蚀时间）对钢材铅铋腐蚀行为的影响机制;澄清了LBE环境下的应力腐蚀与金属脆化机制,总结了内外因素（材料种类、表面缺陷、热处理、氧质量分数、腐蚀温度和拉伸速率）对钢材拉伸性能的影响,并展望了未来铅铋反应堆结构材料的研究方向。建议面向未来的铅铋堆用钢应优化材料设计和处理方式（提高Si、Al等元素的含量、表面镀膜和热处理）同时控制LBE中环境参数（温度、氧质量分数和腐蚀时间）以提高钢材的耐铅铋腐蚀性能。     

考虑释放时间的单机JIT调度问题

本文主要研究二级供应链中的生产-库存-直接配送协同调度问题,其中存在一个制造商和多个零售商, 制造商根据订单进行生产, 然后将产品配送给零售商。该类问题可以抽象为考虑释放时间的单机JIT调度问题。借助于禁忌搜索算法, 本文提出了求解问题的CTA-TS算法, 并通过大量的实验数据与已有算法进行比较,说明了本文提出算法的有效性。     

1-丁基-3-甲基咪唑氯盐-水和2，6-二甲氧基苯酚混合物中分子相互作用的衰减全反射红外光谱研究

Molecular interactions of the ternary mixtures of 1-butyl-3-methylimidazolium chloride ([C₄C₁im]Cl)-water-2,6-dimethoxyphenol (2,6-DMP, a phenolic monomer lignin model compound) were investigated in comparison with the [C₄C₁im]Cl-water binary systems through attenuated total reflection infrared spectroscopy. Results indicated that the microstructures of water and [C₄C₁im]Cl changed with varying mole fraction of [C₄C₁im]Cl (^xIL) from 0.01 to 1.0. This change was mainly attributed to the interactions of [C₄C₁im]Cl-water and the self-aggregation of [C₄C₁im]Cl through hydrogen bonding. The band shifts of C-H on imidazolium ring and the functional groups in 2,6-DMP indicated that the occurrence of intermolecular interactions by different mechanisms (i.e., hydrogen bonding or π-π stacking) resulted in 2,6-DMP dissolution. In the case of ^xIL=0.12, the slightly hydrogen-bonded water was fully destroyed and [C₄C₁im]Cl existed in the form of hydrated ion pairs. Interestingly, the maximum 2,6-DMP solubility (238.5 g/100 g) was achieved in this case. The interactions and microstructures of [C₄C₁im]Cl-water mixtures influenced the dissolution behavior of 2,6-DMP.     

电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰

采用电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰的含量。优化的试验条件如下:1柠檬酸溶液用量为2mL;2过氧化氢溶液用量为12mL;3称样量为0.100 0g;4氨水溶液用量为2mL。选择镍、铁、钴、锰的分析谱线分别为221.647,233.280,228.616,259.373nm。4种元素在一定的质量浓度范围内与其发射强度呈线性关系,方法的检出限(3s/k)在0.018~0.083mg·L-1之间。方法应用于标准物质(JBWY05901)的分析,测定值与认定值相符。方法用于生产样品和合成样品的分析,测定值的相对标准偏差(n=6)在0.72%~3.9%之间。     

电感耦合等离子体原子发射光谱法测定防锈铝合金中痕量钠

提出了电感耦合等离子体原子发射光谱法测定防锈铝合金中痕量钠的方法。以盐酸(1+1)溶液和过氧化氢溶解样品,选择波长588.995 nm为钠的分析线。方法的检出限(3S/N)为0.028 mg.L-1。方法用于测定防锈铝合金中痕量钠(wNa=0.000 14%～0.000 73%),加标回收率在91.4%～113.3%之间,相对标准偏差(n=6)在2.6%～5.5%之间。     

来自“重力势能”的教学探讨

取人教版高中《物理·必修2》"重力势能"一节中,大家争论激烈的两个问题提供参考课例并展开讨论.