电站锅炉运行中换热器传热熵产的试验研究

建立了换热器传热熵产的理论模型,然后利用采集的某火电厂实时运行数据计算得出锅炉运行中换热器的传热熵产变化曲线,并分析了负荷变化和负荷稳定过程中影响其熵产变化的因素,最终提出了可以利用传热熵产监测受热面清洁状况进而开发基于熵产最小理论的吹灰优化新策略的理念.     

邢钢400系低碳易切削不锈钢控碳工艺实践

430F、430FR等低碳易切削不锈钢成品碳含量≤0.035%,由于邢钢采用60 t AOD-LF-CC的低成本生产工艺,其中经常采用造价昂贵的低碳合金和增加末期脱碳时间来保证产品碳合格率,相比同系列的低碳430铁素体不锈钢,吨钢成本升高达100元。通过提高AOD脱碳温度和调整过程碱度,实现出钢[C]≤0.015%。在出钢和精炼工序采用镁钙材质渣线代替镁碳材质渣线的钢包,并调整精炼炉渣氧化性,实现精炼过程平均增碳量≤0.007%。低碳易切削不锈钢整体成品碳含量合格率由76%提高到了≥92%,实现AOD-LF-CC工艺连续生产低碳430系列易切削不锈钢。     

罗非鱼-豆粕共沉淀蛋白的提取工艺及蛋白组成分析

以罗非鱼肉和脱脂豆粕为原料,采用p H调节法制备罗非鱼-大豆共沉淀蛋白（Co-p）,探讨溶解p H、不同质量比混合的原料、溶解时间对可溶性蛋白得率的影响及沉淀p H对蛋白沉淀得率的影响。结果表明,p H调节法回收罗非鱼-豆粕共沉淀蛋白的最佳酸溶p H2.0、3.0,碱溶p H11.0、12.0,原料比1∶1,溶解时间30 min;SDS-PAGE分析显示,可溶性共沉淀蛋白条带深/浅（极端p H2.0蛋白降解）,表明可溶性蛋白含量高/低,从分子量分布范围可知,共沉淀蛋白主要由肌球蛋白重链、7 S抗原蛋白的三个亚基、肌动蛋白、肌球蛋白轻链、11 S抗原蛋白的两个亚基和小分子水溶性蛋白组成,表示可溶性共沉淀蛋白组成齐全;酸/碱可溶性共沉淀蛋白最佳沉淀p H为4.5,在此条件下,溶解、沉淀过程的蛋白得率分别为88.05%⁹4.70%。经冷冻干燥得到共沉淀蛋白粉即Co-p（1∶1）,其蛋白含量高于85%,脂肪含量在0.84%左右,灰分含量低于4.17%;可用p H调节法回收罗非鱼-豆粕共沉淀蛋白。      

自控风干和添加发酵剂对缠丝兔理化及微生物特性的影响研究

采用人工气候箱设定恒定温度、湿度和风速,模拟自然发酵环境,添加复合发酵剂（戊糖片球菌、木糖葡萄球菌、肉色葡萄球菌、清酒乳杆菌、汉逊德巴利酵母菌）0.25 g/kg加工缠丝兔,研究了对产品理化及微生物特性的影响。结果显示,与传统自然风干法比较,新工艺对水分含量和水分活度无显著性影响,但可加快产品p H的下降,且产品最终p H在可接受范围。产品亚硝酸盐、N-二甲基亚硝胺、N-二乙基亚硝胺和组胺分别为110.75、2.23、21.50、26.25μg/kg,而传统加工组为158.37、4.92、52.15、42.12μg/kg。微生物检测结果的差异主要是与发酵肉制品特有感官和风味特性的形成密切相关的乳酸菌和微球菌,新工艺产品为8.25×106、6.33×106CFU/g,远高于传统产品的4.25×105、1.37×105CFU/g。采用自控风干和添加微生物发酵剂显然可在一定程度上降低亚硝酸盐、亚硝胺和组胺等有害物的含量,提升产品安全性。      

拐枣果汁冬枣果粒悬浮饮料的研制

以拐枣和冬枣为试材,研究拐枣果汁冬枣果粒悬浮饮料的制备。在拐枣果汁含量为25%的基础上,探讨冬枣果粒含量和蔗糖、柠檬酸、琼脂的用量对悬浮饮料品质的影响。实验结果表明,以0.30%的Ca Cl2对冬枣果粒进行脆化,效果较好;拐枣果汁冬枣果粒悬浮饮料最佳调配比例为:冬枣果粒15%,蔗糖10%,柠檬酸0.20%,悬浮稳定剂琼脂0.25%。在该条件下制出的果粒果汁悬浮饮料具有较好的悬浮性及稳定性,感官品质良好。      

WT615增压CNG电喷发动机燃烧特性数值分析

以WT615 CNG发动机为模拟研究对象,采用KIVA-3V软件建立了多维软件计算模型,并验证了模型的准确性。在此基础上研究了主要结构参数——燃烧室形状对燃烧特性和整机性能的影响。研究表明,直口形燃烧室的动力性、经济性能最好,更加适用于该天然气发动机,但排放性能有待提高;缩口形燃烧室的整机性能次之,碗形燃烧室的动力性和经济性则较差,后燃现象严重,不适用于天然气发动机。     

A study of apparent apical defects in attenuation corrected cardiacSPECT

There are a number of factors that affect the intensity of the apical region in cardiac SPECT images, which sometime lead to apparent defects in this region. In some patient studies, images reconstructed with non-uniform attenuation correction appear to have a significant decrease of apical intensity, whereas images reconstructed without such correction have only a slight decrease. This phenomenon has been evaluated using a series of simulations, phantom experiments, and a patient study. The effects of a number of factors upon the severity of the apparent apical defects were studied, including: partial volume effect, non-uniform attenuation, and depth-dependent detector response. Simulation and phantom results indicate that (1) since the apex is generally less attenuated than the rest of the heart wall, attenuation correction boosts the intensity of non-apical regions more than that of the apex (by as much as 20%); and (2) partial volume effects due to discretization inadequacies and finite spatial resolution may cause as much as a 26% decrease in reconstructed intensity in the apical region. These two effects, in combination, may partially explain the presence of apparent apical defects when attenuation correction is performed. In addition, detector response compensation consistently reduced the severity of apparent apical defects. These results agree with and help to explain the occurrence of apparent apical defects observed in patient data     

Boundary element alternating method applied to analyze the stress concentration problems of multiple elliptical holes in an infinite domain

This paper presents an efficient boundary element alternating method for analyzing the interactions among multiple elliptical holes in a two dimensional infinite domain under remote uniform stresses. Instead of the analytical solution used in the conventional alternating method, the stress distribution in an infinite domain with a single elliptical hole subjected to the arbitrary tractions across the boundary is solved by the boundary element method. Then this solution correlates with a successive iterative superposition process capable of satisfying the prescribed boundary for each elliptical holes of the problem. Both the effects of various sizes of holes and ligaments among ellipses on the stress concentration are studied in detail. In addition, the computed results and the available referenced solutions closely corresponds to each other indicate the method’s accuracy and efficiency.     

可调式线性油压减振器磨损量的研究

该文以可调式线性油压减振器为研究对象,对其许用磨损量进行了研究。建立了可调式线性油压减振器阻尼性能受其关键磨损量影响的数学模型,对其关键磨损量影响阻尼性能的数值分析结果、机理进行分析,并以额定典型工作点最大可调阻尼力允许下降的极限值为目标,对油压减振器的许用磨损量进行了求解,最后给出了试验验证的方法与结果。