Advanced solvent signal suppression for the acquisition of 1D and 2D NMR spectra of Scotch Whisky

A simple and robust solvent suppression technique that enables acquisition of high‐quality 1D ¹H nuclear magnetic resonance (NMR) spectra of alcoholic beverages on cryoprobe instruments was developed and applied to acquire NMR spectra of Scotch Whisky. The method uses 3 channels to suppress signals of water and ethanol, including those of ¹³C satellites of ethanol. It is executed in automation allowing high throughput investigations of alcoholic beverages. On the basis of the well‐established 1D nuclear Overhauser spectroscopy (NOESY) solvent suppression technique, this method suppresses the solvent at the beginning of the pulse sequence, producing pure phase signals minimally affected by the relaxation. The developed solvent suppression procedure was integrated into several homocorrelated and heterocorrelated 2D NMR experiments, including 2D correlation spectroscopy (COSY), 2D total correlation spectroscopy (TOCSY), 2D band‐selective TOCSY, 2D J‐resolved spectroscopy, 2D ¹H, ¹³C heteronuclear single‐quantum correlation spectroscopy (HSQC), 2D ¹H, ¹³C HSQC‐TOCSY, and 2D ¹H, ¹³C heteronuclear multiple‐bond correlation spectroscopy (HMBC). A 1D chemical‐shift‐selective TOCSY experiments was also modified. The wealth of information obtained by these experiments will assist in NMR structure elucidation of Scotch Whisky congeners and generally the composition of alcoholic beverages at the molecular level.     

苯酰亚胺结构对PET阻燃抗熔滴及抑烟的贡献

通过本体聚合方法合成了一系列侧链含苯酰亚胺结构的聚对苯二甲酸乙二酯(PET)共聚酯.研究发现,苯酰亚胺单元的引入不仅提高了共聚酯的玻璃化转变温度(T_g)和高温成炭性,并且大大降低了共聚酯高温下的热分解速率.随着苯酰亚胺含量的增加,共聚酯表现出更高的氧指数(LOI)值和更好的阻燃抗熔滴效果.锥形量热测试结果表明,苯酰亚胺结构的引入可以有效地降低共聚酯的峰值热释放速率(p-HRR)、峰值烟释放速率(p-RSR)和总烟释放量(TSR).通过对纯PET和共聚酯燃烧测试后残炭的结构和形貌分析,发现苯酰亚胺结构有助于共聚酯形成石墨化程度更高的致密炭层,这些炭层起到隔热隔氧和抑制有机可燃烟气挥发的作用,在不引入传统阻燃剂的情况下,赋予共聚酯很好的本征阻燃性及抑烟性.     

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针对强磁场实验装置(SHMFF)的链式高压有源电力滤波方案规划,基于有源滤波系统的非线性特性, 采用分数阶值。PI 控制器替代普通PI 控制器,在此基础上引入粒子群算法优化指令电流PI 控制器参数,并通过 实验对比分析了人工整定的PI 控制器与PSO 整定的PI 控制器的运行效果。经样机实验表明,采用的PSO 算法 整定的电流内环控制器是正确的,且具有一定的参考价值。     

Comprehensive Theoretical and Experimental Studies on the CF3H Fire‐extinguishing Mechanism

In order to clarify the chemical suppression mechanisms of CF₃H, experimental and theoretical studies were conducted respectively in this paper. Firstly, the combustion species in low pressure laminar premixed flat methane flames with CF₃H addition is measured by synchrotron radiation molecular beam mass spectrometry (SR‐MBMS) experimentally. Fire suppression chemistry of CF₃H is investigated by selective detection of combustion radicals and intermediates in experimental process. Secondly, quantum chemistry calculations are performed to calculate the potential energy surfaces (PES) for the CF₃H unimolecular dissociation reaction and reactions of CF₃H with free radical OH and H at the B3LYP/6‐311++G** and QCISD(T)/6‐311++G** levels. Finally, the chemical suppression mechanism of CF₃H was discussed by comparing the theoretical calculation with experimental measurement.     

Suppression of super-harmonic resonance response using a linear vibration absorber

Super-harmonic resonances may appear in the forced response of a weakly nonlinear oscillator having cubic nonlinearity, when the forcing frequency is approximately equal to one-third of the linearized natural frequency. Under super-harmonic resonance conditions, the frequency-response curve of the amplitude of the free-oscillation terms may exhibit saddle-node bifurcations, jump and hysteresis phenomena. A linear vibration absorber is used to suppress the super-harmonic resonance response of a cubically nonlinear oscillator with external excitation. The absorber can be considered as a small mass-spring-damper oscillator and thus does not adversely affect the dynamic performance of the nonlinear primary oscillator. It is shown that such a vibration absorber is effective in suppressing the super-harmonic resonance response and eliminating saddle-node bifurcations and jump phenomena of the nonlinear oscillator. Numerical examples are given to illustrate the effectiveness of the absorber in attenuating the super-harmonic resonance response.     

柴油舱组集中透气管燃爆危险性及阻隔防爆技术

对常温常压下柴油舱组集中透气管中柴油蒸汽的燃爆危险性以及阻隔防爆技术的抑爆效能开展了实验研究。利用nac HX-3高速相机和CY-YD-205压力传感器记录燃爆传播过程和爆炸超压,阻隔防爆装置分别采用新型抑爆小球和普通波纹型阻火器。结果表明:常温常压下,一旦柴油油舱发生爆炸,爆炸火球可以通过透气管传播到相邻油舱,并引起二次爆炸,具有较大的危险性;普通波纹型阻火器在爆炸过程中阻火失效,而新型抑爆小球具有较好的抑爆效果;相对于光滑透气管工况,在点火舱上方安装抑爆小球后,被点火舱内的最大爆炸超压可以显著地从552.5 kPa降低到35.0 kPa;抑爆小球的中空多孔结构是其阻隔防爆的关键,多孔结构不仅可以增大比表面积、扩大热损失,而且还可以有效地分割削弱反应面。     

In-process sensor for surface profile measurement applying a common-mode rejection technique

An optical non-contact profilometer is presented for super-smooth surfaces, which applies a so-called common-mode rejection technique. Environmental disturbances and laser amplitude noise, which commonly exist in similar instruments, are overcome in this system. The overall simplicity of the optics and electronics, the low cost of the components and the ease of alignment make this a convenient system to implement.     

Optical mm-wave generation by using external modulator based on optical carrier suppression

In this paper, we have theoretically investigated the transmission performance of the optical millimeter (mm)-wave generated by using an external modulator based on optical carrier suppression for the first time. According to our theory, the data signals carried by the optical mm-wave are transmitted in the dispersion fiber without fading but are degraded greatly because of the time shift of the code edges, which still limits the transmission distance. The experimental results agree well with our theory.     

核子诱导的χcJ抑制

本文主要运用夸克交换模型计算所得的核子— χcJ 离解截面研究Pb +Pb和S +Pb中心碰撞过程中强子物质中的 χcJ 抑制 .并定性地研究了核子动量和核子气温度对热平均截面地影响 .Pb +Pb和S +Pb中心碰撞中 χcJ 存活率表明核子与反核子所诱导的 χcJ 抑制是很明显的 .     

CCD变积累控制技术

在分析微光图像噪声特性的基础上，提出了通过对微光图像信号进行积分，抑制随机噪声的方法，发展了ＣＣＤ可变积累控制技术，研制了ＣＣＤ外围驱动控制和视频制式转换系统，使激光图像信号直接在ＣＣＤ电荷包中进行多帧累加，有效地抑制了随机噪声，提高了低照度与低对比情况下的信噪比和灵敏度，同时避免了后续实时处理电路的高原干扰，图像质量有了明显的改善。