高速数字电路设计的电磁干扰控制技术

分析了电磁干扰的特点,阐述了抑制电磁干扰的几种有效的方法,探讨了高速数字电路在噪声抑制方面的设计原则,对于设计高速数字电路具有一定的指导作用。     

基于SA-BFSN算法的多模地面雷达信号预分选方法

针对BFSN算法需要人工输入参数的缺陷,提出了一种自适应确定参数的SA-BFSN聚类方法。该方法利用同一部雷达数据的分布特性进行聚类。通过确定邻居点和比较相似性以达到分选不同的雷达信号,适用于未知雷达信号的分选。提出了合批的方法和一种分选的联合处理。算法测试表明,该方法对噪声不敏感,能够发现任意形状、大小和密度的聚类。     

甚低频十三塔天线电气性能的研究

为了研究影响甚低频天线辐射效率的辐射电阻和地损耗电阻,采用数值仿真与差值相结合的方法,对某双副十三塔甚低频伞形天线中的一副天线进行了数值建模,通过与天线实际测量值对比,验证了天线建模的正确性,研究了天线边塔接地前后天线辐射电阻的变化。在简化该模型的基础上,探讨了天线工作在不同频率下,辐射状地网单圈汇流环位置和汇流环数目对地损耗电阻的影响。     

一种小型平面超宽带天线的设计与实现

提出了一种新颖的小型平面超宽带天线。该天线由矩形微带天线的基本结构演变而来,为获得超宽带频率特性,设计时辐射单元下端采用了渐变结构,金属底板使用缺陷地结构。对天线的反射系数、方向图及增益进行了仿真计算和优化设计,实测结果为:天线的工作频段为3.1~13.0 GHz(S11<-10 dB),增益大于1 dB,具有良好的超宽带特性和全向辐射特性。     

变电站小电流接地数值仿真研究

利用MATLAB仿真平台,对电力系统输电线单相接地问题给出较为准确的数值仿真解,为分析该问题提供了一种简单、可靠的实现途径。通过小电流接地数值仿真研究,可更加清楚小电流接地的物理概念及其动态过渡过程,为小电流接地选线自动化提供更为清,可靠的理论根据。     

Aflatoxin B1 and aflatoxins in ground red chilli pepper after drying

In this study, 180 red chilli pepper (RCP) berry samples were obtained from two different croplands of Gaziantep and Kahramanmara? (Turkey) in August, September and October. RCP berry samples were dried under sunlight and grinded. Ground red chilli pepper (GRCP) samples were analysed for aflatoxins (AFs, sum of B₁, B₂, G₁ and G₂) and AFB₁ contamination. According to the results, in 49 of 180 samples, AFB₁ and in 37 samples, AFs were higher than legal limits. The lowest amounts of AFs and AFB₁ were obtained in August and the highest amounts in October. χ² analysis showed that there were no significant differences (p > 0.05) between cities among 3 months according to number of samples with AFs and AFB₁ above legal limits. According to the Duncan multiple-range test, there was no significant difference between all months. Strict measures are necessary to produce high-quality GRCP. RCP berry must be treated to reduce moulds before production of GRCP.     

挡板式滤汁快速沉降系统在甘蔗糖厂的应用分析

滤汁的稳定处理可大大提高糖厂效能和产品质量,挡板式滤汁快速沉降系统在糖厂的使用表明：设备性能稳定、操作简单、澄清处理效果好,待处理的滤汁不回流,沉清汁完全达到直接入蒸发罐要求,泥汁直接去真空吸滤机或压滤机,较好地解决了滤汁难处理的问题。     

Potential of peanut skin phenolic extract as antioxidative and antibacterial agent in cooked and raw ground beef

This study investigated the potential of peanut skin extract (PSE) as inhibitor of lipid oxidation in cooked and raw ground beef (GB) and as antimicrobial agent in raw GB. Results show that addition of PSE to raw GB before cooking significantly inhibited the formation of peroxides and TBARS in cooked GB during the refrigerated storage. PSE at concentration ≥0.06% was as effective as BHA/BHT at 0.02% in inhibiting lipid oxidation. PSE also inhibited the oxidation of meat pigments thereby preserving the fresh redness of treated meat when used at 0.02–0.10%. Microplate assay showed complete inhibition of test bacteria (Bacillus subtilis, Salmonella typhimurium, Staphylococcus aureus, Streptococcus faecalis and Escherichia coli) in the presence of PSE at 0.4% or higher. However, the antimicrobial effect of PSE in GB was less potent. Hence, PSE can primarily serve the dual purposes of preserving the colour of raw GB and preventing lipid oxidation in cooked products.     

Quality evaluation of raw ground almond kernels (Prunus dulcis): Effect of active and modified atmosphere packaging, container oxygen barrier and storage conditions

The present study investigated the effect of active and modified atmosphere packaging, container oxygen barrier and storage conditions on quality retention of raw ground almonds. Ground almond kernels were packaged in: a) polyethylene terephthalate//low density polyethylene (PET//LDPE), and b) low density polyethylene/ethylene vinyl alcohol/low density polyethylene (LDPE/EVOH/LDPE), under N₂ or with an oxygen absorber and stored either under fluorescent light or in the dark at 4 or 20 °C for a period of 12 months. Quality parameters monitored were: peroxide value (PV), hexanal content, color, fatty acid composition and volatile compounds. Of the sensory attributes color, texture, odor and taste were evaluated. PV ranged between 0.26 for fresh almonds and 19.98 meq O₂/kg oil for almonds packaged in PET//LDPE pouches under N₂ exposed to light at 20 °C after 12 months of storage. Respective values for hexanal were < 28.5 µg/kg and 9.38 mg/kg. Polyunsaturated fatty acids (PUFA) and saturated fatty acids (SFA) increased with a parallel decrease of monounsaturated fatty acids (MFA) after 12 months of storage in samples stored with the oxygen absorber while in samples packaged in PET//LDPE under N₂, a decrease in PUFA and MUFA with a parallel increase in SFA was recorded. Likewise, volatile compounds such as aldehydes, ketones, alcohols, acids, alkanes and aromatic hydrocarbons increased during storage indicating enhanced lipid oxidation. Color parameters L, a and b remained unaffected in all treatments including the oxygen absorber while under a N₂ atmosphere L parameter showed a small but statistically significant (p < 0.05) decrease with a parallel increase (p < 0.05) of a and b values after 12 months of storage. The most pronounced color changes occurred for samples in PET//LDPE pouches irrespective of lighting conditions at 20 °C. Raw ground almonds retained acceptable quality for ca. 6–7 months packaged in PET//LDPE and ca. 8 months packaged in LDPE/EVOH/LDPE pouches under N₂ irrespective of lighting conditions at 20 °C while at 4 °C shelf life was extended by an additional month as compared to storage at 20 °C. Use of the oxygen absorber provided a shelf life of at least 12 months for all samples irrespective of container oxygen barrier, lighting conditions and storage temperature.

Industrial relevance

The use of oxygen absorbers is very effective in extending the shelf life of ground almonds commercially for at least 12 months irrespective of packaging material barrier to O₂, lighting conditions and storage temperature.     

Performance of lactating dairy cows fed ryegrass silage and corn silage with ground corn, steam-flaked corn, or hominy feed

Forty-eight mid-lactation Holstein cows were used in a 6-wk completely randomized block design trial with a 4 × 3 factorial arrangement of treatments to determine the effects of feeding different proportions of corn silage and ryegrass silage with supplemental ground corn (GC), steam-flaked corn (SFC), and hominy feed (HF) on the performance of lactating dairy cows. Forage provided 49% of the dietary dry matter in the experimental diets, which were formulated to meet National Research Council requirements. Ryegrass silage provided 100, 75, 50, or 25% of the total forage dry matter, with corn silage supplying the remainder. There were no interactions between the proportion of forage provided by ryegrass silage and energy supplement. Dry matter intake and milk protein percentage decreased linearly with increasing proportions of ryegrass silage, but milk protein yield was similar among forage treatments. There were no differences among forage treatments in milk yield, milk fat percentage and yield, and energy-corrected milk yield. Dry matter intake was higher and there was a tendency for increased milk fat percentage for GC compared with SFC or HF. No other differences were observed in milk yield or composition among energy supplements. Plasma urea nitrogen and glucose concentrations were similar among treatments. Under the conditions of this trial, our results indicate that feeding a combination of corn silage and ryegrass silage is more desirable than feeding ryegrass silage alone, whereas supplementation with GC, SFC, or HF supports similar levels of milk production.