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排序方式: 共有385条查询结果,搜索用时 147 毫秒
51.
论述粉煤灰-石灰-硫酸盐系统中石灰采用生石灰时,减水剂对粉煤灰活性激发起到了负效应;当以等CaO当量的熟石灰代替生石灰,减水剂对粉煤灰活性激发具有良好正效应,并对其原因进行了初步探讨。 相似文献
52.
介绍了FA322型高速并条机的性能特点及其自调匀整装置的工作原理,在生产中的优越性能和对成纱质量尤其是成纱重不匀的影响。 相似文献
53.
介绍了巴基斯坦古杜电厂S209FA型燃气-蒸汽联合循环“二拖一”机组启动方式及热力系统特点,针对试验过程中旁路控制出现的问题进行了优化和完善,对不同并汽方式进行了验证。高、中压同时并汽有利于汽轮机的推力平衡和稳定运行,由于同时控制设备和参数较多,不易实现自动并汽;先并中压,后并高压蒸汽,最后并入低压蒸汽的方案实现了机组自动并汽,机组负荷稳定,能够满足机组的快速启停和稳定运行的要求,提高了机组的自动化水平。 相似文献
54.
Factors influencing proportion and composition of CLA in beef 总被引:1,自引:0,他引:1
De La Torre A Gruffat D Durand D Micol D Peyron A Scislowski V Bauchart D 《Meat science》2006,73(2):258-268
Bovine meat is criticised for the bad nutritional image of its lipids and fatty acids. However, with dairy products, beef is the major source of conjugated linoleic acid (CLA) which could have several human health benefits. The present study compared, from data of five nutritional experiments on bovine animals performed by the laboratory, the impact of factors linked to the animals (breed, age, sex, type of muscle) and to feeding conditions (basal diet, lipid supplements) on the CLA proportion and composition in muscles. Among these factors, linseed supplementation was an efficient way to increase CLA proportion in beef (+22% to +36%) but was highly modulated by the nature of the basal diet, and by intrinsic factors (breed, age/sex, type of muscle) since these ones could modulate CLA proportion in beef from 24% to 47%. Moreover, these factors modified also the proportion of cis,trans-CLA, related to cis,cis- and trans,trans-isomers. Specific biological properties of these latter isomers should be determine to understand the consequences of intramuscular CLA isomer variations for the health of consumers. 相似文献
55.
Denis P. Dowling Charles E. Nwankire Riitta Keiski 《Surface & coatings technology》2010,205(5):1544-1551
Both organic and inorganic fouling are significant problems for stainless steel surfaces used in industrial applications as diverse as shipping and paper making. The objective of this study is to evaluate the anti-fouling properties of a range of fluoropolymer, fluorinated and non-fluorinated siloxane coatings on stainless steel substrates. These nm thick coatings were deposited using the atmospheric plasma jet system called PlasmaStream™. The surface properties of the plasma polymerised coatings were examined using optical profilometry, SEM-EDX, ellipsometry, contact angle measurement and FTIR. Accelerated wear testing of the coated heat exchangers indicated that coating durability was a significant issue for the nanometre thick coatings investigated. A crystallization fouling study was carried out using a laboratory scale heat exchanger test apparatus. In this the heated steel surface was in contact with flowing fluid containing CaCO3 particles. The coated steel exhibited both a delay before fouling was initiated and in addition a decrease in the fouling rate. A lubricant oil fouling study was also carried out involving a comparison between both coated and uncoated stainless steel separator discs over a 30 day period, in the engine of a passenger ferry. A significant reduction in the level of oil fouling was observed for the fluorosiloxane and fluoropolymer coated separator discs compared with the uncoated discs. 相似文献
56.
针对萤火虫算法在全局寻优搜索中收敛速度慢、求解精度低,易陷入局部极值区域等缺陷,提出一种基于混沌理论的动态种群萤火虫算法。首先,该算法采用立方映射产生的混沌序列对萤火虫位置进行初始化,为全局搜索的多样性奠定基础; 其次,通过对种群的动态监测,每当算法满足预设条件时,基于混沌序列生成部分新的个体,以提高算法的收敛速度; 最后,对每一代产生的全局最优解,适时采用高斯扰动进行变异操作,使算法更具有跳出局部极小的能力。通过对6个复杂Benchmark函数进行测试,实验结果表明,该算法提高了全局搜索能力、收敛速度和解的精度。 相似文献
57.
针对最大类间方差准则下的图像分割结果携带原图信息量不足、实时性差和脉冲耦合神经网络(PCNN)模型中循环迭代次数难以确定的问题,提出了群智能算法优化的结合熵的最大类间方差法(OTSU-H)与PCNN融合的自动图像分割算法。首先,充分利用图像的灰度分布信息和相关信息,将图像信息中冗余度、竞争性以及互补性有效地融合,构造二维和三维观测空间,提出了OTSU-H准则的快速递归算法;其次,将快速递推算法的目标函数分别作为布谷鸟搜索(CS)算法、萤火虫算法(FA)、粒子群优化(PSO)算法和遗传算法(GA)四种群智能算法的适应度函数;最后,将优化之后的OTSU-H引入PCNN模型中自动获取循环迭代次数。实验结果表明,与原始的最大类间方差法(OTSU)、最大熵准则以及基于图论分割、像素的聚类分割和候选区域语义分割的图像分割算法相比,所提算法具有较好的图像分割效果,同时降低了计算复杂度,节约了计算机的存储空间,具有较强的抗噪能力。所提算法时间损耗少、不需要训练的特性使得算法的运用范围较广。 相似文献
58.
为了提高钙钛矿太阳能电池在潮湿环境中的稳定性, 采用一步法, 通过在DMF中混合(EDA)I2、(FA)I和PbI2, 将乙二胺离子引入钙钛矿晶格, 成功制备了一种具有较高稳定性的二维片层状的钙钛矿结构薄膜。通过原位掠入射X射线衍射(GIXRD)、X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)和原子力显微镜(AFM)等方法检测分析(EDA)(FA)2[Pb3I10]在低湿度及高湿度环境下的结构、形貌以及光学性能变化。结果表明: 制备的 (EDA)(FA)2[Pb3I10]薄膜在相同湿度环境下比当前广泛应用于钙钛矿太阳能电池的甲胺铅碘薄膜(CH3NH3PbI3)稳定性更高; 薄膜的光学带隙约为1.67 eV, 与太阳能电池最佳带隙比较接近。另外, (EDA)(FA)2[Pb3I10]薄膜在可见光范围吸光性能较好; 薄膜的粗糙度很小, 适合制备太阳能电池, 而且, 成本较硅基太阳能电池低廉, 在分子水平较CH3NH3PbI3的可调谐性更大, 使钙钛矿太阳能电池在未来大面积应用成为可能。 相似文献
59.
60.
The fatty acid composition of beef and pork has been stigmatized due to their relationships with several diseases from cardiovascular disease to cancer. Meat lipids are, however, one of the few components of meat that can be modified in content and composition, and can present opportunities for value added production and health promotion. Until regulations and policies are in place to define requirements for fatty acid enrichment, however, the process remains relatively academic. Once practical goals are in place for fatty acid enrichment in meat, both theory and practice need to converge for successful production of fatty acid enriched meat. The present review covers aspects of policy in Canada, and requirements for research networks to respond to theoretical and practical challenges associated with production of fatty acid enriched meat. Finally, needs for education and marketing are outlined which must be in place to truly realize a transition of meat lipids from perceived disease and waste to health and opportunity. 相似文献