一种改进的开关磁阻电机磁链模型

开关磁阻电机(SRM)特殊的结构使建立其磁链模型比较困难。根据SRM运行的周期特点,从数学角度用傅里叶级数模型对其进行解析,通过权系数将傅里叶级数模型与传统指数模型结合,得到一个新的改进模型。用提出的改进模型与指数函数模型、傅里叶级数模型分别对Ansoft Maxwell仿真得到的磁链数据进行拟合。对比解析结果,证明提出的改进模型具有更高的解析精度,适合解析磁链。     

The use of infrared spectroscopy and machine learning tools for detection of Meloidogyne infestations

Plant parasitic nematodes are generally soilborne pathogens that attack plants and cause economic losses in many crops. The infested plants show nonspecific symptoms or, often, are symptomless; therefore, diagnosis is performed by taking soil and root tissue samples. Here, we show that a combination of different infrared spectra analysis and machine learning algorithms can be used to detect plant parasitic nematode infestations before symptoms become visible, using leaves instead of roots and soil as samples. We found that tomato and guava plants infested with Meloidogyne enterorlobii produced different spectral patterns compared to uninfested plants. Using partial spectra from 1,450 to 900/cm as the "fingerprint region", principal component analyses indicated that after 5 (tomatoes) or 8 weeks (guava), plants with no visible symptoms of infestations were positively diagnosed. To improve the early detection response, we used machine learning modelling. A support vector machine (SVM) was used to obtain more robust, accurate models. The SVM model contained 34 support vectors, 17 for each level. The overall performance of the model was >97% and the total accuracy was significantly higher, demonstrating the absence of chance prediction. The best prediction of infestation was obtained at the second and fourth weeks for tomatoes and guavas, respectively, reducing the diagnostic time by half. The combined application of these techniques reduces the processing time from field to laboratory and shows enormous advantages by avoiding root and soil sampling.     

Using vibrational molecular spectroscopy to detect moist heating induced carbohydrates structure changes in cool-climate adapted barley grain

There is limited research to study how moist heating affects internal structure of barley grain on a molecular basis. The objectives of this study were to use vibrational molecular spectroscopy: 1) to determine the moist heating induced changes of barley carbohydrate (CHO) structure on a molecular basis, 2) to study the effects of moist heating on CHO chemical profiles, Cornell Net Carbohydrate and Protein System (CNCPS) subfractions, in situ rumen degradation, and predicted intestinal carbohydrate supply of barley grain; and 3) to reveal the association between molecular structure spectral features and CHO related metabolic characteristics. Barley samples (CDC cowboy) were collected from Kernen Crop Research Farm (Saskatoon, Canada) during two consecutive years. Half of each sample was kept as raw barley and the other half underwent moist heating (autoclaving at 120 °C for 60 min). The molecular spectroscopy (attenuated total reflectance-fourier transform infrared, ATR-FTIR) was used to detect the barley CHO related molecular structure spectral features. Moist heating did not affect carbohydrate related chemical profiles and CNCPS subfractions but it decreased rumen degradable carbohydrate. Rumen undegradable and intestinal digestion of CHO subfractions were not affected by moist heating. The advanced vibrational molecular spectroscopy can be used to detect carbohydrate molecular spectral features. Nutrient utilization prediction using molecular spectral characteristics is warranted and further investigation is encouraged.     

酸催化下苯酚液化木材的制备与表征

在硫酸作用下用苯酚对人工林杨木和杉木进行液化,考察反应时间、反应温度等对液化反应的影响,并对液化产物进行表征分析.结果表明:1)在硫酸催化下,杨木和杉木被苯酚液化的历程相似,但残渣含量稍有不同.酸性催化剂不仅对纤维素和半纤维素起作用,对木质素也起作用.2)反应温度比反应时间对液化效率的影响大,二者均能影响液化产物的分子量和分子量分布.通常杉木液化产物的重均分子量高于杨木.3)液化过程中,木质素和半纤维素首先被液化,最后是纤维素.木材组分的分解、酚化和再缩聚反应主宰整个液化动力学过程及液化产物的结构特征.     

醋酸水溶液处理对杉树材影响

为了研究醋酸水溶液处理给杉树材重量带来的变化,使用醋酸水溶液对杉树材进行了处理。结果发现处理后杉树材重量的减小量大约等于抽出物的重量,而且随着醋酸水溶液浓度的增加而增加。利用傅立叶变换红外光谱法对处理后的杉树材及抽出物进行了光谱分析。从处理后杉树材的光谱图可以观察到3400cm-1附近的OH伸缩振动及1510cm-1附近的木质素中苯环C=C伸缩振动的吸收强度有增加倾向。从醋酸水溶液抽出物光谱图可以发现用浓度30%醋酸水溶液处理时木质素被溶出。图2表2参6。     

二维相关红外光谱分析鉴别不同产地黑木耳

不同产地黑木耳的营养成分含量存在差异,因此对黑木耳的产地鉴别具有实用价值。选取8个不同产地的黑木耳,采用傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FT-IR)和二维相关红外光谱(two-dimensional correlation infrared spectroscopy,2D-IR),对不同样本的2D-IR谱图进行处理和分析,并结合系统聚类分析以鉴别黑木耳的不同产地。结果显示,不同产地黑木耳的傅里叶变换红外光谱整体特征极为相似,偏相关系数的最小值为0.955,不能用于区分黑木耳的产地。不同产地黑木耳在1 730～1 400 cm-1、1 350～1 040 cm-1以及1 030～900 cm-1范围内的二维相关红外光谱中自动峰数目不同,它们之间的自动峰和交叉峰的强度也有较大差异;对1 700～950 cm-1范围内的FT-IR光谱进行系统聚类分析,不同产地黑木耳都得到正确归类。结果表明,二维相关红外光谱分析,结合系统聚类分析能够简单、快速、无损地鉴别不同产地黑木耳。     

Effects of long-term green manure application on the content and structure of dissolved organic matter in red paddy soil

Dissolved organic matter (DOM) plays important roles in soil biogeochemistry activity and nutrients transportation in soils, but studies regarding the long-term effects of green manures on the content and structure of DOM in red paddy soil have not been reported yet. A long-term green manure experiment established in 1982 was utilized to test the DOM contents in different treatments, and the spectral characteristics of DOM were investigated by using ultraviolet-visible (UV-Vis) spectrometry and Fourier transform infrared (FTIR) spectrometry. The experiment included four cropping systems: rice-rice-milk vetch (RRV), rice-rice-rape (RRP), rice-rice-ryegrass (RRG) and rice-rice-winter fallow (RRF), among them, milk vetch, rape, and ryegrass are popular winter green manure species in southern China. The results showed that the content of dissolved organic carbon (DOC), which is widely used to estimate the concentration of DOM, was significantly promoted after the incorporation of green manures compared with the other sampling stages. The contents of aromatic groups and the degree of humification of DOM increased in RRV and RRP, suggesting more complex compositions of the soil DOM after long-term application of milk vetch and rape. The contents of phenol, alcohol and carboxylic acid group at the mature stage of early rice were significantly higher than those at the stage of after green manures turned over, especially for the RRV treatment. The absorption ratio of FTIR indicated that winter plantation of rape increased the aromatic-C/aliphatic-C ratio, and ryegrass increased the aromatic-C/carboxyl-C ratio. In conclusion, long-term planting of milk vetch and rape as green manures increased the degree of aromaticity, humification and average molecular weight of DOM, and made the DOM more stable in red paddy soil.     

基于傅立叶耳石形态分析法对几种家鱼仔稚鱼的种类判别分析

于室内养殖条件下研究了鲢(Hypophthalmichthys molitrix)、鳙(Aristichthys nobilis)和草鱼(Ctenopharyngodonidellus)胚后发育阶段矢耳石的形态发育,采用椭圆傅立叶分析法,基于矢耳石形态,比较了以孵化后日龄、耳石形态、发育期以及不同体长组为基础的判别方式上,对这3种家鱼苗的种类判别成功率。结果表明,总判别成功率均表现出了逐渐增加的趋势。孵化后4 d时,总判别率为79.79%;10 d时,总判别率始达90%以上,18 d时,总判别成功率稳定在100%。在尾椎上翘期以前的各发育期,总判别率均低于90%,而鳔二室期之后,总判别成功率达95%以上。据矢耳石形态,圆形和近圆形阶段总判别成功率较低,分别为61%和81%,在长椭圆形阶段后,总判别成功率达90%以上。而以体长为基础的判别成功率,初始总判别成功率便在90%以上。因此,若以判别率的高低为标准,则以不同体长组来鉴别鱼苗种类为最佳,而据耳石形态和发育期来鉴别鱼苗种类,则具有普遍的适用性。     

恒温浴缸加水机制研究

为了确定在没有辅助加热系统浴缸中加热水策略,文章通过对浴缸系统进行热力学分析,建立了浴缸关于时空双因素温度场模型;根据浴缸内部各空间点传热特点,将浴缸注入热水加热过程简化为点热源加热介质问题。利用能量守恒原理,根据傅立叶变换矢量法得出浴缸温度场的分布情况,求得注水点温度最高,边缘温度最低。然后基于浴缸温度场,在忽略人为影响因素条件下建立初级单目标优化模型,确定浴缸水体维持在39~40℃范围内注水流量最小值,结果表明当注水管流量为0.0028m2/s时可以达到预期目的。     

浇筑式钢桥面铺装层推挤变形病害机理分析

以贵州省北盘江大桥钢桥面铺装层推挤变形病害为研究背景,采用凝胶渗透色谱法(GPC)和傅里叶变换红外光谱法(FTIR),从沥青分子尺度分析钢桥面铺装产生推挤变形的原因。分析结果表明:沥青老化并不是造成钢桥面铺装层推挤变形的主要原因;从现场调查可知,第2层粘层粘结能力的降低是造成钢桥面铺装层推挤变形病害的次要原因;通过级配分析发现,造成钢桥面铺装层推挤变形的主要原因是浇筑式沥青混合料(GA)级配偏细以及GA中集料颗粒的棱角性较差所致。