动态饱和鉴相鉴频器

在鉴相鉴频器的复位路径中插入可变延迟单元,利用反馈动态调节延迟时间,可消除死区并且不受环境变化的影响;采用多级鉴相鉴频器,可扩展鉴相鉴频器的工作范围,改善输入输出的非线性,提高鉴相鉴频性能。文章综合两者的优势,提出了一种动态饱和鉴相鉴频器,并把其应用在锁相环中,结果表明该电路在增加的功耗开销小于0.44%的情况下,使得锁相环的锁定时间减小了14%。     

27keV Ar~+离子溅射Cu和CuAu靶时Cu的同位素分馏研究

本文报道了27keV Ar~+离子分别轰击Cu元素靶和CuAu合金靶时溅射Cu原子的同位素(~(63)Cu和~(65)Cu)分馏测量结果,发现:(1)对Cu元素靶,同位素分馏δ_f(~(63)Cu,~(65)Cu)=(62±27)‰,而对Cu-Au合金靶,δ_f=(5.9±1.6)‰;(2)δ_f(~(63)Cu,~(65)Cu)随发射角θ的变化对两者靶而言趋势是相似的,但在CuAu合金靶情况下,当θ≤40°时,δ_f((63)Cu,~(65)Cu)为负值。     

遗传算法在起重机箱形主梁优化设计中的应用

简述了遗传算法的基本原理和计算方法，给出了该算法的程序框图，并使用该算法较好地解决了桥式起重机箱形主梁的优化设计问题。     

铁电性、高温超导电性和庞磁电阻(CMR)效应的共性特征探讨

从结构和相变两个方面探讨了铁电性，高温超导电性和庞磁电阻（CMR）效应的共性，指出这类性质是集体电子行为，是由各种结构层次（晶体结构，电子结构及自旋结构）相互作用，相互耦合共同引起的。     

低NO_x空气分级燃烧技术与锅炉容量的匹配性研究

依据锅炉容量特性以及低NOx空气分级燃烧技术对煤粉气流燃尽过程的影响,分析了低NOx空气分级燃烧技术与锅炉容量的匹配性,以及空气分级燃烧技术应用于中小容量锅炉的可行性及限制因素。研究结果表明,包括SOFA措施在内的深度低NOx空气分级燃烧技术与600MW等级以上的大容量机组锅炉匹配较好,而在300MW等级以下容量机组锅炉上应用需要解决低NOx空气分级技术对煤粉燃尽过程的影响问题。     

深井套管抗挤强度分析及计算

根据弯曲梁理论,建立了套管柱受非均布外挤压力作用的力学模型;并应用解超静定问题的正则方程和力法准则对该力学模型进行求解,得到了在非均布外挤压力作用下套管圆周上的弯矩、剪力、轴力、应力和位移的分布规律。计算表明,在非均布外挤压力作用下,套管抗挤毁强度大大降低。该力学模型不仅可以解释深井套管挤毁机理,而且可以改进深井套管抗挤强度设计。     

淮河上游全新世黄土及沉积成因

The dust source and transporting system are two indispensable aspects in the process of loess-palaeosol accumulation. It has been proved that the dust of the Loess Pla-teau mainly comes from the northwestern inland gobi and desert, transported by the East Asia monsoon systems and westerlies. However, there are little researches with respect to the dust source and deposition dynamics of the upper reaches of the Huaihe River. In the present study, we investigated and collected the YPC section with high resolution in the upper reaches of the Huaihe River. The chronological frame was reconstructed by optically stimu-lated luminescence(OSL)dating and correlated with the published loess time series. By comparison of the magnetic susceptibility(MS)and grain size(GS)of loess-soil profile among YPC profile, XJN profile(western Loess Plateau)and the JYC profile(southern Loess Pla-teau), we find sirnilar climate change and pedogenic process between the upper reaches of the Huaihe River and the Loess Plateau, both experienced an extreme dry and the weakest pedogenesis during the last glacial, followed by a transitional episodes from the cold-dry last glacial to the warm-humid mid-Holocene and increased pedogenesis in the early Holocene,then a most humid-warm and strong pedogenesis in the mid-Holocene, and climate deterio-ration and decreased pedogenesis occurred during the late Holocene. But the MS of loess-soil profile sequences in the upper reaches of the Huaihe River was much lower than those in the Loess Plateau, and the GS was much coarser than those in the Loess Plateau.Comparison of GS for these three profiles revealed that there were different dust sources,which belonged to different aeolian transporting systems. The loess in the upper reaches of the Huaihe River was a wind blown deposition of near source, while the coarser dust mainly came from loose alluvial deposits of alluvial and proluvial fans of the Yellow River. The yield-ing and carrying dynamics of the dust in the Huaihe River is the northeast wind prevails in the winter half year.     

The equivalent circuits for polaronic relaxation: Taking the LaNi3/4Mo1/4O3 as a model sample

We herein discuss the equivalent circuits for polaronic relaxation based on the results of the low-temperature dielectric properties of LaNi_3/4Mo_1/4O₃. The ceramic samples were prepared via solid-state reaction route. The dielectric properties were investigated in the temperature range from 103 K to 330 K and the frequency range from 20 Hz to 10 MHz. Our results showed that the Debye-like relaxation found in the sample was related to be a polaronic relaxation caused by localized carriers. At low enough temperatures below 103 K, the carriers were strictly confined and the equivalent circuit for impedance spectra was an ideal capacitor. At the temperatures around room temperature, the carriers can hop between spatially fluctuating lattice potentials, the circuit of R???CPE (R?=?resistance, CPE?=?constant phase element) was found to be the better model to describe the impedance data.