云环境下基于虚拟机动态迁移的调度策略研究

针对目前云环境资源调度采用静态负载均衡策略易于导致资源浪费的问题,提出了一种双限定值的虚拟机动态迁移的调度策略.该策略将当前负载状况与负载过重或过轻时两个限定值比较,选择介于二者之间能耗较低的虚拟机迁移至目标节点.仿真实验表明,该策略能够减少迁移次数,降低虚拟机迁移能耗,从而尽可能达到负载均衡和满足服务等级协议的需求.     

简易式多功能膛口装置结构及其性能指标的计算法

该文介绍一种被命名为内插管扩张型多功能膛口装置.其结构比较简单,且具有消焰、消声、制退和有利于提高射击精度多种功能.本装置各项性能指标的计算法,是采用实验与理论分析相结合建立的经验公式,既可用作正面计算,也可用作多目标函数综合优化设计的反面计算.     

Bottom-Up法计算油田注入水中三种细菌的不确定度

为保持地下压力,在油田开采过程中需向地下油层中注水,注入水中最为常见的三种细菌是腐生菌、铁细菌和硫酸还原菌,这些细菌的存在会降低注入水水质并腐蚀管道,影响油田开采。为客观评价三种细菌检测的准确度,采用绝迹稀释法检测技术,利用Bottom-Up法,通过21组数据对三种细菌检测方法的不确定度进行计算。结果表明,绝迹稀释法检测油田注水三种细菌的不确定度分别为:硫酸还原菌±4 mL^-1,腐生菌±6 mL^-1,铁细菌±16 mL^-1。通过Bottom-Up法对检测不确定度进行评估,可真实、准确地反应油田注入水中三种细菌的实际含量范围,为油田注水达标提供技术保障。     

响应面法优化纯种根霉米粉种曲制作工艺

针对纯种根霉（Rhizopus）米粉种曲制备过程中缺乏系统控制、质量难以稳定的问题,研究其关键影响因素,优化种曲的制备工艺。以一级籼米米粉为原料,接种纯种根霉制备种曲,在单因素试验的基础上,以种曲的试饭糖分值为响应指标,利用Box-Behnken响应面设计试验优化种曲制作工艺,确定纯种根霉米粉种曲的最佳制备工艺为试管菌种培养时间72 h、二级种曲培养温度32 ℃、米粉水分含量25%。在此最佳工艺条件下进行验证试验,实际测得种曲的试饭糖分平均值为27.18 g/100 g,与模型的理论预测值非常接近,拟合成功;该模型优化工艺可为纯种根霉曲的生产提供参考。     

Optimality of the Münch mechanism for translocation of sugars in plants

Plants require effective vascular systems for the transport of water and dissolved molecules between distal regions. Their survival depends on the ability to transport sugars from the leaves where they are produced to sites of active growth; a flow driven, according to the Münch hypothesis, by osmotic gradients generated by differences in sugar concentration. The length scales over which sugars are produced (L_leaf) and over which they are transported (L_stem), as well as the radius r of the cylindrical phloem cells through which the transport takes place, vary among species over several orders of magnitude; a major unsettled question is whether the Münch transport mechanism is effective over this wide range of sizes. Optimization of translocation speed predicts a scaling relation between radius r and the characteristic lengths as r ∼ (L_leaf L_stem)^1/3. Direct measurements using novel in vivo techniques and biomimicking microfluidic devices support this scaling relation and provide the first quantitative support for a unified mechanism of sugar translocation in plants spanning several orders of magnitude in size. The existence of a general scaling law for phloem dimensions provides a new framework for investigating the physical principles governing the morphological diversity of plants.     

Effects of Reducing Gas on Swelling and Iron Whisker Formation during the Reduction of Iron Oxide Compact

The effects of different types of reducing gas on swelling and iron whisker formation during the reduction of iron oxide compacts were investigated. The compacts sintered in air at 1273 K were reduced at 1173 K in different reducing atmospheres. The results indicated that catastrophic swelling can happen in CO but not when H₂ is present in the reducing gas mixture. Scanning electron microscope (SEM) micrographs showed that catastrophic swelling was caused by a large amount of long iron whiskers formed during the reduction. The presence of N₂ and CO₂ in CO changed the amount of long iron whiskers and its distribution, which determined the extent of swelling.     

三元流叶轮置换技术在聚酯生产中的应用

通过全三元射流-尾迹流动计算得出定量分析,改善叶轮内流动状态,减少进口冲击和出口尾迹脱流等损失,使水泵效率得以提高,真正达到节能降耗之目的。     

弱磁精选设备在磁铁矿降硅提铁中的研究与实践

阐述了弱磁精选设备对磁铁矿降硅提铁技术研究及应用的意义，指出弱磁场磁选设备若可以达到降硅提铁目的，磁选工艺应是首选方法。分析了常规磁选设备用于降硅提铁分选精度不高的原因，介绍了弱磁场降硅提铁磁选设备的研究及应用现状。生产实践表明，磁聚机和磁选柱用于磁铁矿降硅提铁效果明显。     

喷雾降尘机理的研究

为了更好地利用喷雾技术高效沉降煤矿生产中作业场所的高浓度粉尘，对喷雾降尘机理进行了深入研究.以煤矿井下回风巷道中沉降浮尘为研究对象，分析影响粉尘沉降效率的因素，建立了相应的数学模型，应用MATLAB软件绘制出粉尘沉降效率曲线.由此得出，水雾粒径越小降尘效率越高，但不同粒径的粉尘颗粒对应一个较佳的水雾粒度；当采用压力型雾化喷嘴沉降浮尘时，降尘效率主要取决于供水压力，不同粒径的粉尘需要的水压力不同，依据实际粉尘颗粒的分散度和降尘要求参照曲线图来选择合适的供水压力，可以达到更好的效果和经济效益.     

Sugar Beet Grown Using Nutrient Film Technique: Yield and Nutritional Quality

Sugar beet (Beta vulgaris L cv Great Western Sugar) was grown using the nutrient film technique with a half-strength modified Hoagland nutrient solution to determine its biomass yield and nutritional quality. After 6 months, storage root and foliage weights per plant were 493·1 g and 551·0 g, respectively. Sucrose content in the fresh storage root was 118·4 g kg⁻¹ but was less than 10 g kg⁻¹ in the fresh leaves and petioles. Some nutrients in the leaves and petioles were analysed to evaluate their potential as a leafy vegetable. Fresh leaf protein, total dietary fibre, mineral (Ca, Mg, Zn, Fe and K), vitamin (carotene, ascorbic acid and thiamine) and oxalic acid concentrations were similar to those of consumer-accepted green vegetables.