需求弹性对发电系统可靠性的影响

在电力市场环境下,由于负荷需求弹性的存在,面对电价的波动,用户可适时调整负荷计划,改变实际负荷曲线,从而直接影响发电系统可靠性的计算。构筑考虑需求弹性的电价负反馈模型,通过对IEEE30节点系统进行计算,研究了需求弹性对发电系统可靠性的影响,也即对电源充裕度的影响。     

分布式参数输电线路电磁暂态分析新方法

根据函数逼近原理,输电线路的电报方程可以整理为一组正交基的线性组合。文章采用Daubechies正交基,经过投影变换,映像到与依赖于时间变量的和建立在确定架构的函数空间,与输电线路的电压和电流相关的微分方程被转换为代数矢量方程。从而,建立起每一单元的投影等效模型,然后可以在投映域中对输电系统的暂态进行计算。利用EMTP仿真验证了所建议的方法。     

Evaluation of high temperature polymers in nanolayered films and gradient refractive index (GRIN) lenses

A new polymer nanolayer gradient refractive index (GRIN) system with more robust thermal stability because of incorporation of a high glass transition temperature polyester, OKP4HT, was demonstrated. A combination of extruded nanolayered GRIN film systems, comprised of five unique polymer materials, were combined to produce laminate optics comprised of a large internal refractive index gradient distribution, n = 1.445 – 1.630, without degradation of optical transmissive properties. The optical performance of a series of varied magnitude GRIN lenses, ranging from Δn = 0 to 0.185, was evaluated. Increasing the lens refractive index range resulted in decreased optic sphericalaberrations that followed analytical predictions. An analytical approach was reported to correlate the polymer material upper service temperature (UST) to the onset of polymer material loss modulus as measured by DMTA. Thermo‐optical interferometry measurements of irreversible lens deformation confirmed the lenses UST at 125°C for the OKP4HT/PC system as compared to 75°C for a PMM/SAN17 system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42741.     

Manufacturing of polymer continuous nanofibers using a novel co-extrusion and multiplication technique

A novel co-extrusion and two-dimensional multiplication technique was developed for continuous production of nanofibers using melt-processable polymers. This solvent-free and environment-friendly fiber fabrication approach has significant advantages over existing solvent-based techniques such as electrospinning. The flexibility of the co-extrusion processing for nanofiber fabrication is demonstrated using three examples. Multicomponent extrudate strands of polycaprolactone (PCL)/polyethylene oxide (PEO), polyamide 6 (PA6)/polyethylene terephthalate (PET) and polyethylene (PE)/polypropylene (PP) were fabricated for nanofiber production.     

新疆东天山灵北地区康南岩体岩石学#br# 特征及其构造意义

研究区位于新疆东天山觉罗塔格造山带吐哈盆地以南百灵山以北,多年来对于研究区古生代构造背景的认识受前人热议,存在争议。通过对研究区新发现基性岩体的岩石、地球化学特征与构造背景进行探讨,以期为大区域构造背景的研究提供一定的数据支持。主量元素研究表明,康南岩体具有高Mg、Fe,低Al的特征,说明研究区基性侵入岩为碱性岩石系列。微量元素测试结果表明具有同源演化的特征,Rb、Hf元素亏损较为严重。K、Ba、P、Sm富集明显,Tb、Nb、Ti表现为弱异常,在稀土元素球粒陨石标准化配分模式图中Eu的负异常不明显,表现为弱的正异常, Yb+Nb-Rb构造环境判别图解中样品落在“后碰撞”环境内,以上特征说明具有岛弧花岗岩的基本特征。岩性为深灰绿色弱蚀变细粒橄榄辉绿岩。     

SYNERGISTIC EFFECT OF VITAMIN B1 ON SANITIZER AND DISINFECTANT TREATMENTS FOR REDUCTION OF BACILLUS CEREUS IN RICE

The synergistic bactericidal effects of vitamin B₁ (thiamine dilauryl sulfate) and the efficacy of commercial sanitizers for minimization of Bacillus cereus contamination in cooked rice were investigated. Sanitizer-treated rice exhibited a greater reduction than water-treated rice, while sanitizer-treated rice with Vitamin B₁ produced an even greater reduction. The treatments for B. cereus in rice included (1) 100 ppm hydrogen peroxide with 500 ppm vitamin B₁; (2) 200 ppm hydrogen peroxide with 100 ppm vitamin B₁; (3) 400 ppm hydrogen peroxide; (4) 50 ppm chlorine with 500 ppm vitamin B₁; (5) 60 ppm chlorine with 300 ppm vitamin B₁; (6) 70 ppm chlorine with 100 ppm vitamin B₁; (7) 80 ppm chlorine; and (8) 100,000 ppm ethanol with 500 vitamin B_1. All treatments completely eliminated B. cereus in rice. The sensory properties of all sanitizer-treated cooked rice did not differ significantly from the same properties for water-treated cooked rice.

PRACTICAL APPLICATIONS

The prevalence of Bacillus cereus in rice and rice products has been documented and control of the growth of B. cereus in rice is an important consideration. The results obtained from this study can be of use to rice producers in the manufacture of safe products. Although chemical disinfectants can be used to reduce the amount of B. cereus in rice, vitamin B₁ can also be used as an effective additive that reduces the amount of disinfectant use via a synergistic antimicrobial effect. The increasing use of chemical disinfectants for safety in the food industry can be reversed using our method.     

Influence of dietary fish oil on conjugated linoleic acid and other fatty acids in milk fat from lactating dairy cows

Lactating cows were fed menhaden fish oil to elevate concentrations of conjugated linoleic acid, transvaccenic acid, and n-3 fatty acids in milk. Twelve multiparous Holstein cows at 48+/-11 DIM were assigned randomly to a replicated 4 x 4 Latin square. Each treatment period was 35 d in length, with data collected d 15 to 35 of each period. On a dry matter (DM) basis, diets contained 25% corn silage, 25% alfalfa hay, and 50% of the respective concentrate mix. Fish oil was supplemented at 0, 1, 2, and 3% of ration DM. Linear decreases were observed for DM intake (28.8, 28.5, 23.4, and 20.4 kg/d) and milk fat (2.99, 2.79, 2.37, and 2.30%) for 0 to 3% dietary fish oil, respectively. Milk yield (31.7, 34.2, 32.3, and 27.4 kg/d) increased as dietary fish oil increased from 0 to 1% but decreased linearly from 1 to 3% dietary fish oil. Milk protein percentages (3.17, 3.19, 3.21, and 3.17) were similar for all treatments. When the 2% fish oil diet was fed, concentrations of conjugated linoleic acid and transvaccenic acid in milk fat increased to 356% (to 2.2 g/ 100 g of total fatty acids) and 502% (to 6.1 g/100 g), respectively, of amounts when 0% fish oil was fed. There were no additional increases in these fatty acids when cows were fed 3% fish oil. The n-3 fatty acids increased from a trace to over 1 g/100 g of milk fatty acids, when the 3% fish oil diet was fed. Fish oil supplementation to diets of dairy cows increased the conjugated linoleic acid, transvaccenic acid, and n-3 fatty acids in milk.     

茶叶辐照的热释光分析研究

不采用二次辐照,将TL 分析法应用于辐照茶叶的定性鉴定。分离并收集茶叶中黏附的硅酸盐,采用热释光剂量仪测量获得硅酸盐的热释光发光曲线,比较未辐照与辐照不同剂量茶叶的热释光发光曲线的积分强度、峰值和峰值温度等特征参数。未辐照茶叶的热释光发光曲线的积分强度小于50、峰值小于0.4、峰值温度大于260℃;反之,辐照茶叶的热释光发光曲线的积分强度大于50000、峰值大于600、峰值温度位于160～190℃。TL 分析法能判别出茶叶的辐照与否,尤其对不能满足参比剂量辐照条件的样品很有帮助。     

碱性pH对马鲛鱼肌球蛋白热聚集行为的影响

为探究碱性条件下pH对马鲛鱼肌球蛋白热聚集行为的影响,以马鲛鱼肌球蛋白为研究对象,探究在加热条件下pH（7.0、8.0、9.0）对肌球蛋白的结构和理化性质（溶解度、浊度、二级结构、总巯基含量、表面疏水性）的影响,未加热组作为空白对照组。结果表明：对照组肌球蛋白在pH（7.0、8.0、9.0）下溶解度从68.00%升高到82.00%、浊度变化不明显;加热组则有较大差异,溶解度从30.00%增加到94.00%,浊度吸光值从0.49降低到0.23;加热组pH 9.0的肌球蛋白α-螺旋含量减少,在所有组中含量最低,为45.60%,β-折叠含量增加,为10.60%;加热组的巯基含量呈下降趋势,由70.45 nmol/mg减少到50.11 nmol/mg,碱性pH下的蛋白质有助于巯基向分子间和分子内二硫键的转化;随着pH值的增加,对照组肌球蛋白的表面疏水性系数依次增加,而加热组下降,但加热组肌球蛋白的表面疏水性系数仍然远高于对照组。综上所述,通过探究碱性条件下肌球蛋白热聚集体的性质,有助于对其热聚集进行调控,获得一种热稳定性较好的肌球蛋白溶液,对以后研究其作为乳化剂添加到食品中有重要意义。