酶辅助空化处理对豆渣纤维结构和理化性质的影响

该研究通过傅里叶变换红外光谱、X-衍射、扫描电镜等分析方法分析水力空化、酶解处理对脱脂豆渣纤维结构和理化性质的影响。研究结果表明：空化处理强烈影响了豆渣纤维的理化性质,空化10 min时豆渣纤维的持水力与持油力分别达到18.43 g/g和7.35 g/g,空化处理20 min使可溶性膳食纤维含量（Soluble Dietary Fiber,SDF）由2.87%升至6.97%,溶液表观黏度降低,豆渣纤维出现蜂窝状片状结构,豆渣纤维结晶度降低。酶辅助空化处理可以进一步改善豆渣纤维的理化性质,且受酶解先后顺序强烈影响,其中,先酶解后空化豆渣中的SDF含量可达12.52%,溶液表观黏度明显降低,先空化后酶解的样品则表现出更高的持水力与持油力。酶辅助空化处理豆渣出现较多碎片结构,纤维尺寸变小。酶辅助空化处理可以作为一种有效改善豆渣纤维结构和理化性质的手段。     

INFLUENCE OF WATER ACTIVITY ON THE ACOUSTIC PROPERTIES OF BREAKFAST CEREALS

Corn and wheat bran flakes were compressed in a plastic cylinder and the generated vibrations were measured by a piezoelectric accelerometer. Amplitude–time records were thoroughly analyzed and the total acoustic energy in arbitrary units, number of acoustic events and energy of a single acoustic event were calculated. Relationships between the time of compression, frequency and sound intensity are presented as acoustograms. All parameters, except the energy of a single acoustic event, were strongly dependent on water activity (A_w). The flakes differed essentially in their ability to propagate vibrations. At low A_w's, both types of flakes were alike, but at higher A_w's, corn flakes damped high‐frequency waves while wheat bran flakes did not show this property.     

自振空化射流提高钻井速度的实验研究

空化射流用于提高钻井速度的可行性研究结果表明，在钻进作业中，利用空泡破裂产生强大破坏作用来提高钻探的效率，其效果显著，可行性高。室内实验表明，自振空化射流在比普通喷嘴射流更深的井底或更高的围压条件下，有更大的起始空化数和更强的空化能力。自振空化喷嘴起始空化数大都在1.0以上，最高达到1.67，而锥形喷嘴最高仅为0.43，围压下其冲蚀效率是锥形喷嘴的1~2倍。现场试验同样证实设计的自振空化射流喷嘴在保护钻头、减少钻头磨损及增加进尺、提高机械钻速方面有显著作用。     

Next target for food hydrocolloid studies: Texture design of foods using hydrocolloid technology

Texture is important in terms of both food palatability and the safety of eating. Recently, the importance of texture has been emphasized for the development of nursing-care foods, including dysphagia foods, in recent aged society, where the number of patients with mastication and swallowing difficulties is increasing. Texture design of these food products is now one of the most important tasks in the food industry in Japan. Texture of these food products should be optimized by modulating viscoelasticity using hydrocolloids so that they can easily transform to ‘ready-to-swallow’ bolus during oral processing. This article reviews the importance of texture as an essential attribute of foods and also the usefulness of hydrocolloids as an ingredient to modify and control food texture. The article also covers recent trials by the author’s research team on bolus rheology and in vivo acoustic analysis. The trials are to find some objective parameters describing the mastication and swallowing eases as an alternative to conventional bulk rheology and subjective sensory analysis.     

基于神经网络算法的复合材料板声发射源定位

使用Levenberg-Marquardt训练函数的神经网络算法在复合材料板上进行声发射定位,采用声波到达时间作为输入向量,训练得到了到达各个传感器的声波触发时间与板上坐标的良好的映射关系.考虑到波形衰减,用传统的固定门槛提取的到达时间容易与实际情况偏差较大,讨论了一种相对准确的适合工程使用的到达时间提取方法.     

Ultrasound Enhanced Sanitizer Efficacy in Reduction of Escherichia coli O157 : H7 Population on Spinach Leaves

ABSTRACT:  The use of ultrasound to enhance the efficacy of selected sanitizers in reduction of  Escherichia coli  O157 : H7 populations on spinach was investigated. Spot-inoculated spinach samples were treated with water, chlorine, acidified sodium chlorite (ASC), peroxyacetic acid (POAA), and acidic electrolyzed water with and without ultrasound (21.2 kHz) for 2 min at room temperature. The effects of ultrasound treatment time and acoustic energy density (AED) were evaluated at an ASC concentration of 200 mg/L. The effect of ASC concentration, with a fixed AED of 200 W/L, was also examined. Microbial analysis indicated that ASC reduced  E. coli  O157 : H7 population by 2.2 log cycles over that of water wash, while the reduction from other sanitizers was about 1 log cycle. Ultrasonication significantly enhanced the reduction of  E. coli  cells on spinach for all treatments by 0.7 to 1.1 log cycle over that of washes with sanitizer alone. An increase in the ASC concentration enhanced the efficacy of the combined treatment of ASC and ultrasonication, especially at ASC concentrations of < 300 mg/L. Increasing the ultrasound treatment time from 0 to 4 min and AED from 0 to 500 W/L were both effective in increasing the effectiveness of the ASC and ultrasound combined treatments. In addition,  E. coli  O157 : H7 inoculated on the underside of spinach leaves (rough side) were more difficult to remove than those inoculated on the upper side (smooth side).     

超超临界储水罐调节阀及管配系统汽蚀特性分析

针对合川电站超超临界锅炉储水罐调节阀出现的严重汽蚀现象,基于两相空化流动方程和FLUENT流场数值模拟方法,对该调节阀及其管配系统的流场特性进行分析。将模拟结果与实际失效结果相比较并提出优化方案。结果表明:基于FLUENT的空化模型模拟结果与实际工程失效情况比较吻合,加长出口管道至4m后,在三通底板处速度降低71.4%,含汽量降低84.9%。该分析方法对储水罐调节阀设计有较好的指导作用,对促进其国产化进程也有积极意义。     

采场安全监测与冒顶预报

本文总结了声发射现场监测预报的试验结果，提出了采场稳定性预测的综合方法，应用灰色理论预测和神经网络方法较好地解决了采场冒顶预报问题。     

高压锅炉给水泵主轴拉细和平衡盘磨损原因分析

叙述了多级泵主轴拉细、气蚀和平衡盘磨损而导致多次停机检修的情况,详细进行了主轴拉细的强度计算,以及发生气蚀和平衡盘磨损的原因,并提出了解决的具体措施．     

扫描速度对半导体激光熔覆钴基合金涂层组织与性能的影响

采用2 kW半导体激光器在304不锈钢表面进行同轴送粉的激光熔覆Co基合金试验。通过扫描电镜（SEM）、X射线衍射仪（XRD）研究了不同扫描速度下熔覆层的显微组织和相结构;采用显微硬度计、摩擦磨损试验机和气蚀装置分别测试了不同扫描速度下熔覆层的显微硬度、耐磨性与抗气蚀性能。结果表明,不同激光扫描速度下合金涂层皆无裂纹与气孔,随着扫描速度增加,合金涂层的硬度、耐磨性能与抗气蚀性能则先增强后降低,在激光扫描速度为900 mm/min时,合金涂层具有较好的硬度、耐磨性和抗气蚀性能。