沙埝地区阜三段储层精细对比新方法

针对沙埝油田构造破碎,断层发育,且井多在目的层钻遇断层,火成岩发育,储层精细对比困难等特点,通过对该区测井曲线仔细研究,找到了适合本区储层精细对比的新方法,即利用标准曲线在区域或局部电性岩性标志层控制下的旋回对比法对比地层,利用感应曲线寻找局部电性岩性标志层控制下的精细对比法对比储层.研究表明,该方法对阜四段地层和阜三...     

Perception of melting and flavor release of ice cream containing different types and contents of fat

Temporal effects of dairy and vegetable fats (0 to 18%) on perception of strawberry flavor release and melting of ice cream were studied using the time intensity sensory method. Also, aroma and flavor attributes of the ice cream samples were evaluated. Only slight effects of fat on the rate of flavor release and flavor intensity were perceived. A slightly faster flavor release from the vegetable fat compared with dairy fat was noticed. Polydextrose and maltodextrin as bodying agents in the fat-free ice cream significantly increased flavor release and melting rate of the ice cream. Increasing fat content slightly retarded melting of ice cream in the mouth. No significant effect of the fat quality on perceived melting was noticed. Significant differences in aroma and flavor attributes of the fat-free and other samples were perceived. Intensity and sharpness of the strawberry aroma and flavor were greater in fat-free samples and they were perceived as nontypical. Fattiness and creaminess were highly correlated. Maltodextrin and polydextrose increased perceived fattiness and creaminess of fat-free ice cream.     

低渗水敏性储层岩心水驱前防膨处理实验研究

通过静态防膨率测试,筛选出对低渗水敏性储层防膨效果好的防膨剂及其用量.动态防膨效果实验表明,已水驱过的低渗岩心受到伤害后再注防膨剂,伤害的岩心不能恢复;注防膨剂溶液比单纯注水的岩心伤害率小,但停注防膨剂改注水,岩心伤害率迅速上升.提出低渗水敏性储层注水开发前应采取防膨处理措施.     

Variability in oil content and fatty acid composition in wild northern currants

Seed oils of wild berries of alpine currant (AC) and northern redcurrant (NRC) were investigated. Oil contents of AC and NRC varied between 4.9 % and 9.7% and between 12.8% and 38.5%, respectively. The proportions of α-linolenic, γ-linolenic and stearidonic acids were higher in NRC (means of 21.7, 12.3 and 5.4%, respectively) than in AC (16.8, 8.6 and 3.0%). The growth areas of NRC can be divided into two distinct groups according to the proportions of different polyunsaturated fatty acids. Oil content of NRC correlated negatively to the proportion of linoleic acid and positively to that of stearidonic acid. There were significant correlations between all polyunsaturated fatty acids in NRC but correlations were less obvious in AC. Interestingly, the correlation between linoleic and γ-linolenic acids was positive in NRC but negative in AC. α-Linolenic and stearidonic acids showed positive correlations in both species. In NRC the synthesis of triunsaturated fatty acids is directed either towards α-linolenic or γ-linolenic acids. Results showed great potential in NRC and AC for plant breeding due to the natural variation in the content and composition of the seed oils for functional nutrients. Received: 20 August 1999 / Revised version: 29 October 1999     

基于复杂结构数据聚类的推荐系统

针对目前推荐系统存在的不能处理结构复杂、语义丰富领域的推荐问题以及对项目空间和用户空间本质特征理解的狭窄性和简单性、稀疏性问题、可扩展性问题,研究了基于复杂结构数据聚类的推荐方法,提出了一个新颖、有效、具有高可扩展性的基于复杂结构数据聚类的混合型推荐系统HRSCCSD.该系统能同时融合用户语义、项目语义和项目协同多方面...     

面向对象数据库中的频繁模式发现

提出了基于高阶归纳逻辑编程发现面向对象数据库中的频繁模式的算法.此算法使用高阶逻辑编程语言Escher作为数据及模式表示语言.由于高阶逻辑编程语言不仅能描述复杂结构的数据而且还能描述复杂的模式,以及Escher语言的强类型语法能有效缩小由于高阶逻辑编程语言较强表达能力所带来的较大的模式搜索空间,故此算法能充分利用面向对...     

一种基于多因素耦合的谐波减速器传动精度逆向分析方法

谐波减速器的传动误差是由零件加工及装配过程中的几何偏心和运动偏心等偏心矢量耦合而成的,具有频域性特点,并且各种单因素引起的传动误差分布概率符合瑞利分布.通过空间运动学、谐波啮合原理,建立了基于瑞利分布的传动误差多因素耦合模型,完成了置信区间可达99％的谐波减速器传动误差的预判模型.通过预判模型能够计算出各传动误差源的权...     

Adaptive Optimal Output Regulation of Interconnected Singularly Perturbed Systems With Application to Power Systems

This article studies the adaptive optimal output regulation problem for a class of interconnected singularly perturbed systems(SPSs) with unknown dynamics based on reinforcement learning(RL). Taking into account the slow and fast characteristics among system states, the interconnected SPS is decomposed into the slow time-scale dynamics and the fast timescale dynamics through singular perturbation theory. For the fast time-scale dynamics with interconnections, we devise a decentralized optimal co...     

网状纤维结构氧化镍的制备及其气敏性能

p型半导体金属氧化物作为气敏材料具备响应快速、选择性高的特点,用于气体传感器的制备与开发。静电纺丝法可制备具有丰富气体吸附位点的网状结构材料,增强材料的气体敏感特性。以聚乙烯吡咯烷酮(PVP)、四水合乙酸镍为原料,采用静电纺丝法制备具有网状纤维结构的p型半导体氧化镍。通过X射线衍射、扫描电镜、X射线光电子能谱和比表面积测试等分析技术对材料的结构、形貌、组成和比表面等性能进行表征,并对其气敏性能进行测定,考察煅烧温度对材料气敏性能的影响。结果表明:煅烧温度为500℃时获得的氧化镍组装成气体传感器,在工作温度为250℃时,该元件对50mg/L丙酮气体表现出快速响应特性(响应时间为5s)、良好选择性和稳定性。     

布拉酵母高密度发酵培养基及发酵工艺优化

为实现布拉酵母高密度培养,对其高密度发酵培养基和发酵工艺进行优化。采用Plackett-Burman试验筛选培养基中的显著因素,并进行中心组合设计。通过人工神经网络（artificial neural network,ANN）和响应面试验建立菌体布拉酵母产量与培养基之间的关系模型,利用遗传算法（genetic algorithm,GA）进行全局寻优。结果表明,ANN模型有较好的数据拟合能力和预测能力,更适合处理复杂的非线性问题。GA优化获得最佳培养基组合：葡萄糖40.52 g/L、蛋白胨36.8 g/L、玉米浆17.32 g/L、硝酸钾14 g/L、酵母营养盐1.5 g/L、磷酸二氢钾0.6 g/L、硫酸镁0.8 g/L。利用该培养基进行摇瓶培养,菌体布拉酵母产量可达到8.21 g/L,比优化前提高1.39 倍。在此基础上利用1 L发酵罐培养确定最佳发酵工艺：温度30 ℃、接种量10%、pH 5.0、溶氧40%。利用50 L发酵罐进行扩大培养,流加葡萄糖和蛋白胨控制发酵液中葡萄糖3 g/L、氨氮0.06 g/L,菌体布拉酵母产量达到51.21 g/L。