半固态铝合金汽车动力零件的疲劳分析模型开发（英文）

汽车悬架控制臂被用来连接转向节和车架,其主要功能是在加速和制动的装载和脱载的疲劳应力作用下提供稳定性。一般情况下,这些零件采用钢材制备,导致油耗量和污染气体排放量增加。最近,有研究尝试研发更轻、更耐疲劳的半固态A357铝合金以取代钢质悬架控制臂。本研究旨在更好地理解运用数学模拟识别疲劳应变强化参数,以便确定铝合金悬架控制臂的疲劳特性。最佳的方法是对标准试样进行疲劳测试,然后以循环次数分别作为应力和变形的函数,绘制两条Wohler曲线。利用这些曲线和特定的数学分析方法,可以得到所有的参数。计算出的新参数表明,与同一合金的相同分析曲线相比,A357铝合金样品的实验疲劳曲线明显改善。     

基于陶瓷膜技术的羊乳酪蛋白和其他组分的高效分级分离

为量化0.05 μm陶瓷膜脱除羊乳中乳清蛋白、乳糖、灰分、钙和磷的能力,在50 ℃条件下,脱脂乳进行3 倍浓缩,之后2 次间歇补水至原体积进行清洗过滤,最终得到1 份截留液、3 份透过液,并计算各组分总脱除率。结果表明：乳清蛋白脱除率为96.17%,乳糖脱除率为86.42%,灰分脱除率为73.39%,钙脱除率为34.90%,磷脱除率为55%。稀释过滤完毕后膜的纯水膜通量衰减系数为55.57%,使用质量分数为2%氢氧化钠和1%的硝酸溶液进行清洗,膜通量的恢复系数为99.21%。0.05 μm陶瓷膜可以实现羊乳酪蛋白和其他组分的有效分离,该技术适合在没有干酪乳清的条件下,以生鲜乳为原料加工酪蛋白胶束粉、乳清蛋白粉、乳糖等乳基配料产品。     

基于图像处理的储粮低密度虫害监测系统的设计与验证

为解决高害虫密度储粮处理成本昂贵和现有监测系统实时性和移动性不足等问题,采用Web技术,结合自主设计的粮虫诱捕器,建立了储粮低密度虫害实时监测系统。树莓派控制诱捕器采集害虫图像并进行图像处理得到图像中害虫的数量,再将数据传至云端服务器,用户通过Web客户端获取历史以及实时的害虫图像和害虫数量。在实验室用该系统监测了赤拟谷盗密度为0.5、1、2、3、4、5头/kg的稻谷,通过系统捕获第一只害虫的时间来评价其灵敏度,24 h内对害虫的捕捉率验证系统用于低密度虫害监测的可行性,并以人工直接计数结果为参考计算了系统计数的准确率,结果表明：系统灵敏度高,在低密度害虫条件下对害虫的捕捉率高于61.98%且诱捕器捕捉的害虫数与稻谷中的害虫总数存在显著线性关系,系统计数准确率为90.26%。因此,该系统可用于低密度虫害的实时监测。     

超声处理改善羊乳理化性质及其酶凝胶流变学特性

在超声频率20 kHz,超声功率800 W,超声时间15、20、25、30 min的条件下处理生羊乳,分析超声处理对羊乳粒径、Zeta-电位、表面疏水性和二级结构的影响,并通过流变学分析和扫描电子显微镜观察进一步研究添加凝乳酶对羊乳酶凝胶的流变学特性和微观结构的影响。结果表明,超声处理降低了羊乳样品的粒径,使蛋白质的二级结构发生明显变化,β-折叠和无规卷曲相对含量增加,α-螺旋和β-转角相对含量降低,β-折叠结构相对含量与表面疏水性呈正相关（r＝0.74）。与对照组（未处理的生羊乳和巴氏杀菌羊乳）相比,较长时间（超过20 min）超声处理能显著提高最大储能模量（G’max）（P＜0.05）,但超声处理25、30 min的羊乳凝乳时间缩短。扫描电子显微镜结果显示超声处理羊乳样品的凝胶微观结构更加致密。综上,超声处理可以有效改善羊乳酶凝胶品质,在实际生产中具有潜在的应用价值。     

Development of fatigue analytical model of automotive dynamic parts made of semi-solid aluminum alloys

Automotive suspension control arm is used to join the steering knuckle to the vehicle frame. Its main function is to provide stability under fatigue stresses of loading and unloading in accelerating and braking. Conventionally, these parts were made of steel; however, fuel consumption and emission of polluting gases are strongly dependent on car weight. Recently, there is a try to develop and design much lighter and better fatigue resistant metal of semisolid A357 aluminum alloys. This work aims at a better understanding of identifying the fatigue strain-hardening parameters used for determining fatigue characteristics of aluminum suspension control arm using analytical and mathematical modeling. The most judicious method is to perform the fatigue tests on standardized test pieces and then plot two Wohler curves, mainly number of cycles as a function of the stress and as a function of the deformation. From these curves and following a certain mathematical and analytical methods, certain curves are plotted and then all of these coefficients are drawn. The new calculated parameters showed a clear improvement of the fatigue curve towards the experimental curve performed on the samples of aluminum alloy A357 compared with the same analytical curve for the same alloy.     

Prediction of ductile fracture using isotropic and kinematic hardening rules including void nucleation

A formulation combining kinematic translation and isotropic expansion for a yield surface based on Gurson–Tvergaard function is used to describe void growth. By adopting a criterion of internal necking of the ligaments between voids, fracture strains for tensile bars made of conventional alloys and powder metal compacts—with micromechanical parameters mostly identified from experiments—are predicted according to kinematic, isotropic and mixed hardening models. Fracture strains predicted by the kinematic‐hardening model are in closer agreement with experiments whereas those estimated according to isotropic‐hardening model are overestimated. The consideration of either step‐like or continuous void nucleation models indicates its great influence on fracture strains and emphasizes a further need to quantify the statistical parameters involved in these models.     

New overlapped decentralized controller for large-scale systems

This paper is devoted to the development of a new decentralized control approach for large-scale interconnected dynamical systems. The proposed decentralized control structure is based on the concept of overlapping decomposition. The controller gains for the overlapped subsystems are calculated only once and they are easy to compute since all operations are carried out at the subsystems level. Since the proposed decentralized controller operates under a completely decentralized information pattern, the inaccessible states for each augmented subsystem are estimated using a set of overlapped decentralized estimators. A sufficient condition is developed for the stability of the global system with the decentralized control scheme subject to structural perturbations. It is shown that with the satisfaction of this condition, the proposed controller provides a robust design which is insensitive to structural perturbations.