浓度对“微量”样品NMR信号影响

本工作利用微量核磁管(Φ2.5 mm)和常规核磁管(Φ5 mm)对同一化合物同等质量(2 mg)两份样品进行多种核磁共振实验,对两种不同浓度下NMR信号进行分析,并利用微量样品管顺利完成对头孢硫脒的结构确认。实验结果表明:当可用于测试样品量较少时,利用微量样品管提高样品测试浓度可明显地改善核磁谱图质量;微量样品管在小样品量的NMR分析中具有潜在应用价值。     

Aerodynamic noise numerical simulation and noise reduction study on automobile alternator

Aerodynamic noise is the predominant component of automobile alternator noise at high speed, which directly affects the noise characteristic and noise control of alternator. Based on Lighthill acoustic theory, the aerodynamic noise of an automobile alternator was simulated with three-dimensional, Large eddy simulation (LES) and Ffowcs Williams-Hawkings (FW-H) acoustic model, and the aerodynamic noise reduction research was conducted through optimizing the front fan blade spacing angle of alternator with vector composition method while considering high fan flow and optimal noise frequency components for reduced harmonic rotating noise of alternator. The results show that the sound pressure amplitude of the primary aerodynamic noise components simulated with LES are in good agreement with experimental ones, and the dominant harmonic frequency components of aerodynamic noise are in the 4th, 6th, 8th, 10th, 12th and 18th orders and the A-weighted sound pressure level of one-third octave mainly concentrates in 1120-7000 Hz. The average total noise level of alternator noise is decreased by 2.58 dB, and the mass flow of monitoring surface of fan blade is increased by 1.36 g/s with 5.80 dB decrease in the sound level of the 12th and 18th harmonic orders on average with optimized front fan blade spacing angles, which verifies the effectiveness of the noise reduction method proposed in this paper.     

智能配电网环境下负荷预测研究

智能配电网环境下,负荷预测精度的高低影响着电网运行的安全性和经济性,为了提高负荷预测精度,提出了人工鱼群-反向传播算法（AFSA-BP）的电力负荷预测模型。传统BP算法由于输入神经元,隐层神经元和输出神经元之间的初始权值和阈值为随机获取,降低了算法的收敛速度和预测精度,采用AFSA算法对BP算法的初始权值和阈值进行全局寻优,获得最优的网络模型。在分析了电力系统负荷特性的基础上,采集历史负荷数据,天气和节假日信息,采用AFSA-BP算法建立短期负荷预测模型。为了验证该算法的准确性,分别采用BP、最小二乘-支持向量机（LS-SVM）、AFSA-BP算法对某省的电力负荷进行仿真实验,AFSA-BP算法的均方根误差（RMSE）为0.0862,而BP算法和LS-SVM算法的RMSE分别为0.2558和0.1522,结果验证了AFSA-BP算法适用于短期电力负荷预测。     

新型含N杂环化合物的合成及其摩擦学性能研究

合成了一种新型含N杂环化合物添加剂,利用红外光谱仪定性分析了其结构,利用热重试验和油溶性试验考察了其热稳定性及其对液体石蜡基础油的感受性,利用四球和HQ-1环块试验机考察了其摩擦学性能。结果表明其具有较好的热稳定性及其对液体石蜡基础油良好的感受性,能降低长磨磨斑直径和减小摩擦因数,有效提高基础油的摩擦学性能。     

电空制动系统微机控制单元电磁辐射的测量

随着科学技术的飞速发展越来越多的新技术应用到了我们的生活中,与此同时带来的电磁辐射问题值得我们研究。本文结合当前最新的理论,基于取样区间长度,样本间隔和取样频率等提出了电空制动系统微机控制单元电磁辐射的测量方案并且进行了测量和分析。     

High-temperature tribological properties of strontium sulfate films formed on zirconia-alumina, alumina and silicon nitride substrates

In our present study, Al₂O₃, (ZrO₂–3 mol% Y₂O₃)–39.6 mass% Al₂O₃ and Si₃N₄ substrates coated with SrSO₄ and SrSO₄–10 mass% Ag films were prepared, and the friction and wear properties of these specimens were investigated using a reciprocating ball-on-disk tribometer in the temperature range from room temperature to 1073 K in air. It was clarified that (ZrO₂–3 mol% Y₂O₃)–39.6 mass% Al₂O₃ substrates coated with chemically precipitated SrSO₄ particles and the substrates coated with SrSO₄–10 mass% Ag films prepared by mechanically grinding and annealing at 1073 K for 3.6 ks exhibited low friction coefficients and low wear rates at all the testing temperatures. In addition, the average friction coefficients of Si₃N₄ substrates were reduced above 673 K by coating with chemically precipitated SrSO₄ particles.     

色多项式与图的平面性

设图Ｇ的色多项式为Ｐ（Ｇ，λ），α＿１（Ｇ）是Ｐ（Ｇ，λ）中λ项的系数的绝对值。本文证明了：若１≤α＿１（Ｇ）≤２３，则图Ｇ是连通的平面图。     

洪江古镇建筑的文化含义透视--在社会心理的层面上进行探讨

"有机"的洪江古镇建筑遗存丰富,特色鲜明.该文从其建筑的外在形态着手,在社会心理的层面上对当地的文化含义做了一定的研究和探讨,希望对于积累当地建筑的资料、加深人们对于当地建筑的理解、实现文化可持续发展有所帮助.     

玄武岩纤维布加固钢筋混凝土梁受弯受剪承载力计算分析

基于现行混凝土结构加固设计规范关于粘贴纤维增强复合材料加固法的计算理论,分别对玄武岩纤维布和碳纤维布加固钢筋混凝土梁的正截面受弯承载力、斜截面受剪承载力进行计算分析,以探讨玄武岩纤维布对钢筋混凝土梁的加固效果。计算结果表明,设计人员可以方便地按现行加固设计规范对玄武岩纤维受弯、受剪加固进行计算。     

数据中心机房设计的总体要求

1数据中心机房设计的规范依据1)《建筑内部装修设计防火规范》GB50222-952)《高层民用建筑设计防火规范》GB50045-95(2005版)3)《计算站场地安全要求》GB9361-88