自制AlMg40中间合金的生产实践

在铸造铝合金中,镁是一种主要元素,又是一种易烧损元素。镁的加入量很低,用镁锭直接配料操作很不方便。如何方便而准确的加镁,是铸造铝合金生产的一大问题。我们通过生产试验,找到了一种AlMg40合金,解决了这一问题。该合金生产工艺简单,满足了中间合金的使用要求。 1.原生产中配镁的操作 (1)镁锭锯成小块,搭配使用。这样既浪费材料,又提高成本。 (2)镁锭刨成屑。这样镁氧化严重,对熔炼铝     

稀土萃取槽混合室结构研究

以实际工程中应用的稀土萃取槽混合室为研究对象,运用Fluent软件分析挡板对稀土萃取槽混合室内料液搅拌效果的影响,采用标准k-ε湍流模型和多重参考系法模拟了不安装挡板和安装不同数量挡板的混合室内的流场和湍动能,并进行对比分析。研究结果表明,安装挡板会改变混合室内的流场结构,使轴向流动得到明显增强;而且挡板能有效限制切向速度,增大轴向和径向速度以及湍动能,加强了混合室内料液的搅拌混合特性;根据模拟结果分析找到了能改善混合效果的挡板数量。     

用硅铁镁合金作球化剂的经验

过去我厂是用镁锭制成的镁屑结作球墨铸铁的球化剂。后来因镁锭供应困难,就改用飞机镁制作镁屑结。但飞机镁也远远满足不了生产的需要,而且还要增加一道熔制成锭的工序。同时飞机镁的成分往往不稳定,再加上用镁屑结做球化剂烧损太多,常出现铸件球化不良现象。在这样的情况下,如何减少镁     

利用冷凝侧回收热调控供液温度特性分析

针对某型液冷源供液温度波动较大以及冷凝侧热无利用排放问题,通过对系统工作原理和冷凝侧换热器结构等方面进行分析,提出可以利用冷凝侧回收热控制供液温度波动或实现供液温度的精确控制。建立了冷凝侧换热器的计算模型,并计算出系统冷凝侧空气进、出口温度、冷凝温度和冷却液出口温度等工作参数,以及在不同工况下的热回收量。结果表明,通过冷凝侧热回收的方式对液冷源供液温度进行调控,能够抑制供液温度波动,避免压缩机频繁启停,提高液冷源工作稳定性;冷凝侧热回收时,最大冷却液旁通流量为总流量的50%左右最为合适,并总结了系统制冷量与总热负荷能够实现平衡的工况区域。研究结论结果可为相关领域冷凝侧热利用提供参考。     

潜室对稀土萃取槽混合室流场特性影响的模拟分析

采用计算流体力学的方法,研究四种潜室结构对混合室混合效果的影响,利用利用湍流模型与Mixture多相流模型耦合,多重参考系法处理搅拌桨叶附近的旋转区域,对混合室液-液两相混合进行数值模拟。结果表明:隔板式混合室入料口物料流量最小,管式混合室的口流量最大;搅拌桨周围负压由大到小依次是无隔板式、管式、V字式和隔板式;综合抽吸流速和功率损耗两方面,管式结构最佳。     

液料射流下等离子电弧温度场的仿真分析

利用有限元分析软件Fluent,研究了液料等离子啧涂中等离子枪口到待处理基板之间的等离子射流温度场分布特性,并考察了液料入射速度对等离子喷射特性的影响。结果表明,等离子射流的温度场形貌呈倒锥形分布,并沿径向呈高斯分布衰减;随着液料入射速度增大,等离子弧的温度峰值没有变化,等离子射流轴线上距枪口越远处温度下降越快。谱线标准温度法对等离子射流CCD图像的处理数据与模拟计算值基本吻合,验证了计算结果的准确性。     

流式细胞仪流动室的聚焦特性分析

利用流体质量守恒定律和层流模型对侧壁鞘液入口呈对称分布的流动室结构进行理论分析,推导了样本流聚焦直径的理论公式,并且使用Ansys Fluent对流式细胞仪中的关键部件流动室进行了流体仿真模拟。结合数值仿真结果探讨了鞘液流速、样本流入口直径、鞘液入口直径、检测区直径对聚焦效果的影响,并采用正交实验分析了各个因素对其产生影响的程度,为建立流式细胞仪流动室预测模型及优化结构设计提供了参考依据。     

注射模工艺参数对塑件翘曲量的影响及优化

利用Moldflow分析软件,采用数值模拟的方法分析了料温、模具温度、注射时间、冷却时间和保压压力等工艺参数的变化对塑件产品翘曲的影响趋势及其原因。结果表明:对所选参数,保压压力对塑件翘曲的影响最为显著,且保压压力取注射压力的95%左右可使产品的翘曲量达到较小的程度;产品翘曲量随料温升高,注射时间减短而减小;冷却时间对翘曲量的影响甚微;模具温度对翘曲影响较为复杂。根据分析结果,优化了塑件的成型工艺参数,使得翘曲量进一步减小。     

树脂固化温度与纤维铺设方式对C/E复合材料制孔质量的影响

在碳纤维树脂复合材料制备及加工过程中均较容易产生各种缺陷,并影响构件最终的加工质量及使用性能.为研究碳纤维树脂复合材料制备过程中产生的缺陷对制孔出口质量的影响,提出一种通过改变预浸料固化温度模拟材料制造缺陷的方法,并对不同温度固化和不同方式铺设的样件进行了模拟制孔试验,分析剩余刚度对材料内部缺陷扩展及制孔出口质量的影响...     

白屈菜根生物碱提取工艺研究

以白屈菜根为原料,采用索氏提取法提取生物碱,采用单因素试验和正交试验设计方法研究了料液比、提取时间、提取温度等因素对白屈菜根生物碱提取效果的影响。结果表明:提取白屈菜根生物碱的最佳工艺条件为提取时间3.0h、提取温度95℃、料液比1:25。提取温度对提取效果影响最大,其次为料液比,提取时间影响最小。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.