用AOM研究强非线性齿轮系统动力学问题

在考虑齿轮时变啮合刚度、阻尼、啮合误差及齿侧间隙的情况下,建立了具有5自由度的二级齿轮传动系统的动力学模型。为了便于用AOM法求解,用多项式拟合齿侧间隙,而将啮合刚度、啮合误差、输入转矩波动及输出转矩波动用Fourier级数表示。利用Adomian分解算法的思想,用AOM法得到了齿轮系统的近似解析解。根据计算结果,AOM法克服了谐波平衡法的滤波缺陷,能够保留所有的频率成分,其中包含有基频、倍频及组合频率等成分,因此,可以方便、可靠地用AOM法研究齿轮系统的动力学问题。     

Relationship between rancimat and active oxygen method values at varying temperatures for several oils and fats

Determination of oxidative stability of different edible oils, fats, and typical fat products was made using the Rancimat method and the active oxygen method. Induction periods (IP) were recorded under controlled conditions at 110, 120, and 130 ± 0.1°C for all products and over a range of 100–160°C for selected fats. A general oil stability evaluation industrial shortenings and vanaspati to be the most stable fats, with IP ranging from 10.00 to 15.47 h. Margarine and butter samples (IP, 4.98–6.04 h) were also found to show fair oxidative stability. Among the extracted and open-market salad-grade cooking oils, rapeseed oil (IP, 4.10 h) and soybean oil (IP, 4.00 h) showed the highest oxidative stability, whereas Salicornia bigelovii oil (IP, 1.40 h) was the least stable. The induction periods of typical fat products ranged from 2.59 to 9.20 h. CV for four determinations were <5.2% for shortening and vanaspati products and <4.3% for various vegetable oils, margarine, butter, and typical fat products. Rancimat IP values obtained at 110, 120, and 130°C were 40–46, 20–25, and 9–13% of active oxygen method values, respectively, corresponding to a decrease in Rancimat IP by a factor of 1.99 with each 10°C increase in temperature. Similarly, in the temperature range 100–160°C, an increase of 10°C decreased the Rancimat IP by a factor of 1.99     

基于声驻波原理的高频声光正弦调制器

介绍了一种基于声驻波原理研制的高频声光正弦调制器,分析了声驻波在晶体中形成的相位光栅的周期性变化特征,介绍了该高频声光正弦调制器的设计原理并对其性能进行了测试和分析。该声光正弦调制器调制频率达到300 MHz,驱动源结构简单,易于制作。     

NIM4#铯冷原子喷泉钟电子测控系统的研制

本文简要叙述了用于NIM 4 #钟电子测控系统的PC软件的功能及时序控制系统、声光调制器驱动源、微波综合器和微波接口箱的功能和硬件设计。最后较详细叙述了NIM4 #钟数据采集与频率闭环控制比对的过程。     

油脂的氧化稳定性测试

油脂在贮存过程中会由于发生氧化反应和水解反应最终导致酸败。测定油脂酸败程度的方法多种多样,但最有指导意义的是对油脂氧化反应过程中诱导期的测定。采用氧化稳定性测则试了多种常用油脂的氧化稳定性,模拟了油脂氧化初期的过程,对预测油脂的货架寿命有一定指导意义。     

油溶型茶多酚的制备及其抗氧化性能的研究

采用酰化的方法制备油溶型茶多酚。以猪油和大豆油为实验油,用活性氧法（ＡＯＭ）对粉剂茶多酚、油溶型茶多酚、叔丁基４羟基茴香醚（ＢＨＡ）＋２,６－二叔基对甲酚（ＢＨＴ）的抗氧化性能进行了比较。实验结果表明：油溶型茶多酚的抗氧化效果优于粉剂茶多酚和ＢＨＡ＋ＢＨＴ,它对猪油、大豆油抗氧化效力分别为ＢＨＡ＋ＢＨＴ的２倍和１．５倍。     

激光多普勒技术测量大尺寸直径的研究

介绍了激光多普勒技术用于大尺寸直径测量的原理 ,并据此设计了新型差动激光多普勒大尺寸直径测量系统。采用差动型光学系统并使用声光调制器对测量光束进行调制 ,提高了系统的测量精度。高频信号和低频信号分开处理 ,消除了信号的相互干扰。实验结果反映了系统良好的线性度。线性回归的相关系数达到 0 .9999,相对测量精度为 3× 10 - 4 。     

Effects of alginate oligosaccharide mixtures on the growth and fatty acid composition of the green alga Chlamydomonas reinhardtii

Alginate is a natural acidic linear polysaccharide that is produced by brown seaweeds. It is currently used in a broad range of commercial enterprises, such as the food and medical products industries. Recent evidence has demonstrated that alginate oligosaccharides may function as growth promoting agents for certain plant cells, including those of some green algae. Chlamydomonas reinhardtii is a green alga that is used as a model organism in fundamental molecular biology studies; it is also a producer of biohydrogen. In the present study, we examined effects of two types of alginate oligosaccharide mixtures (AOMs), which were prepared by either enzymatic degradation (ED) or acid hydrolysis (AH), on the growth of C. reinhardtii. Growth was significantly promoted by AOM (ED) in a concentration-dependent manner. The maximum effect was observed on day 4 of treatment. The fatty acid composition of C. reinhardtii was also influenced by AOM (ED); the levels of C16:0, C18:2 cis and C18:3 n-3 increased in treated cells. AOM (AH) and the other saccharides that we tested did not affect the growth of C. reinhardtii. The effects that we identified could promote efficient biomass production by reducing culture times and by changing cellular fatty acid levels.     

提高声光调Q光纤激光器输出功率的关键因素分析

声光调Q光纤激光器具有所需驱动调制电压很低,容易实现对连续激光调Q获得高重复频率脉冲输出的特点。介绍了声光调Q光纤激光器的原理,并对影响它性能的几个重要因素如自发辐射的放大、泵浦功率和速率、光纤的选择、声光Q开关的重复频率等主要因素做理论分析,提出了优化这些因素的方法。     

转矩激励对二级齿轮系统脱啮行为的影响

在考虑齿轮时变啮合刚度、阻尼、转矩波动及齿侧间隙的情况下,建立了具有5自由度的二级齿轮传动系统的动力学模型.为了便于用算法分解算法求解,用多项式拟合齿侧间隙,而将啮合刚度、输入及输出转矩波动用Fourier级数表示.利用Adomian分解算法的思想,用AOM得到了系统对转矩激励的动力学响应.仿真结果表明,在某些转速区段,转矩激励会导致强烈振动;在低速齿轮对中,可能同时伴随脱齿现象,并导致较大的动载荷.