稀土元素Ce对取向硅钢热轧钢带组织和织构的影响

对2250 mm热轧生产线生产的取向硅钢热轧钢带的合金体系进行了设计,制定了合理的加热制度和热轧轧制工艺。对添加稀土元素Ce的取向硅钢铸坯和热轧钢带进行了分析,探究了稀土元素Ce对取向硅钢低倍组织、热轧织构及成品磁性能的影响。结果表明,稀土元素Ce能够细化取向硅钢连铸坯低倍组织和热轧显微组织,提高取向硅钢成品磁性能。     

超分子作用阻尼材料的动态力学模型修正

为提高飞机起落架载荷实测精度，以支柱式起落架结构为研究对象，探讨处理其载荷标定数据的工程方法。首先，对实际受载情况和单向加载工况标定数据的分析，挖掘出三向载荷、缓冲支柱压缩行程与应变码值间的数学关系，将预测的数学关系代入到多向工况的标定数据中，验证了它们的准确性;其次，根据两种标定数据回归方法，提出了对应使用的支柱式起落架载荷-应变标定方程的数学模型;最后，将两种标定方程代回到标定数据中，计算起落架三向载荷，所有反算载荷的误差均在可控范围内，表明标定方程满足精度要求。将标定方程代入实测数据中，实测曲线符合变化规律。该处理方法的应用能有力提高支柱式起落架的起飞-着陆载荷实测和载荷谱编制的准确度。     

3D numerical study on flow structure and heat transfer in a circular tube with V-baffles☆

A 3D numerical investigation has been carried out to examine periodic laminar flow and heat transfer character-istics in a circular tube with 45° V-baffles with isothermal wal . The computations are ba...     

双弹性板矩形空腔内噪声的有源力控制

研究了在弹性板上施加不同参数的有源力对腔内噪声进行控制的问题。构建双弹性板构成的封闭矩形声腔模型，对封闭声腔的结构 声耦合特性进行分析，推导了在封闭声腔有源力控制作用下声压计算公式，给出采用有源力控制的最优控制模型。分析了弹性板在不同参数的次级力源激励下腔内局部声场的声压级响应，并建立了仿真模型对局部声场的减噪效果进行分析。结果表明，合理选择次级力源的参数对控制效果的影响较为明显，且次级力源的个数并非越多越好。     

Ejector in R410A vapor compression systems with experimental quantification of two major mechanisms of performance improvement: Work recovery and liquid feeding

This paper presents experimental data and analysis comparing the performance of an R410A ejector vapor compression system to those of a liquid-fed evaporator system and a conventional expansion valve system. The objective was to quantify separately two major improvements of the ejector system: work recovery and liquid-fed evaporator. The ejector system was first compared to a system with liquid-fed evaporator at matching cooling capacities and revealed improvements from 1.9% to 8.4% solely due to the work recovery of the ejector. When compared to a conventional expansion valve system at the same cooling capacity, the ejector setup improved COP from 8.2% to 14.8% due to simultaneous benefits of liquid-fed evaporator and work recovery. Overall ejector efficiencies from 12.2% to 19.2% were achieved.     

Iron Loss Calculation of AC Filter Inductor for Three‐Phase PWM Inverters

In recent years, remarkable advancement of new power semiconductor devices, such as SiC and GaN, enables the increase of switching frequency of power converters, and hence the volume of passive components, such as ac filters and transformers, can be reduced. However, temperature rise caused by the inductor loss is increasing, and hence iron loss evaluation of the inductor is one of the most important issues to realize high power density converters. Conventionally, an improved generalized Steinmetz equation (iGSE) has proposed in order to calculate the iron loss under a pulse voltage magnetizing condition. However, accurate iron loss calculation of the ac filter inductor used in a PWM inverter cannot be realized. The authors have proposed two methods of iron loss evaluation of ac filter inductors. The first one is a loss map method which can calculate the iron loss without using a real PWM inverter. Another one is an ILA (Inductor Loss Analyzer) which can measure the iron loss in every switching period in a real PWM inverter. In this paper, comparisons of the iron loss between the ILA and the loss map method on both the single‐phase and three‐phase inverters are studied. It is found that iron loss of the ac filter inductor in the three‐phase PWM inverter which is calculated by the loss map method cause a large error on a specific condition. In order to prevent the calculation error, the authors proposed a revised loss map method and proved the effectiveness of the method.     

Effects of Sm-doping on microstructure,magnetic and microwave absorption properties of BiFeO_3

In this paper,polycrystalline samples of Bi_(1-x)Sm_xFeO~3(x=0,0.05,0.1,0.15) were successfully synthesized by sol-gel method.The effects of Sm concentration on the crystal structure,morphology,chemical states,magnetic properties and microwave absorption performance were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),a vibrating sample magnetometer(VSM) and a Vector network analyzer(VNA),respectively.The results show that the rare earth Sm doping causes the crystal structure to change.When x≤0.1,Bi_(1-x)Sm_xFeO_3 is the distorted rhombohedral structure with space group R3 c.With the increase of Sm doping amount to x=0.15,the phase structure of Bi_(1-x)Sm_xFeO_3 changes from rhombohedral structure to cubic structure with the space group Pm3 m.The particle size decreases with the increase of the Sm doping amount.The analysis results show that Sm doping can effectively reduce the oxygen vacancies and significantly improve its magnetic properties.The results exhibit that moderately doped rare earth Sm element can effectively improve microwave absorption properties of Bi_(1-x)Sm_xFeO_3 powders.When Sm doping amount of x is 0.1,the Bi_(0.9)Sm_(0.1) FeO_3 compound has good microwave absorption performance,and the minimum reflection loss value of Bi_(0.9)Sm_(0.1)FeO_3 powder reaches about-32.9 dB at11.7 GHz,and its effective absorption bandwidth(RL -10 dB) is 2.6 GHz with the optimal matching thickness of 2.0 mm.     

基于密集神经网络的灰度图像着色算法

针对在灰度图像着色领域中，传统算法信息提取率不高、着色效果不理想的问题，提出了基于密集神经网络的灰度图像着色算法，以实现改善着色效果，让人眼更好地观察图片信息的目的。利用密集神经网络的信息提取高效性，构建并训练了一个端到端的深度学习模型，对图像中的各类信息及特征进行提取。训练网络时与原图像进行对比，以逐渐减小网络输出结果的信息、分类等各类型的损失。训练完成后，只需向网络输入一张灰度图片，即可生成一张颜色饱满、鲜明逼真的彩色图片。实验结果表明，引入密集网络后，可有效改善着色过程中的漏色、细节信息损失、对比度低等问题，所提算法着色效果较基于VGG网络及U-Net、双流网络结构、残差网络（ResNet）等性能优异的先进着色算法而言取得了显著的改进。     

动车组司机室空调蒸发器气动噪声数值仿真

为研究动车组司机室空调蒸发器的噪声响应，建立某型司机室分体式空调蒸发器的计算流体动力学模型，采用FLUENT中的大涡模拟（large eddy simulation, LES）计算瞬态气动流场。对瞬态流场数据进行傅里叶变换，得到空气流场的频域数据。基于流场频域数据，采用Virtual.Lab的边界元法计算蒸发器的气动噪声，采用声压法计算蒸发器的辐射声功率，并与测试结果进行对比分析。结果表明：蒸发器出口位置气动噪声最高，最大声压级高于56 dB；最大声功率级出现在125~400 Hz的低频段；声功率级随着频率的增加逐渐降低，但在5 000 Hz的高频辐射中声功率级仍然超过55 dB，这表明空调蒸发器气动噪声属于宽频噪声；计算结果与测试结果吻合良好，验证声压法计算空调蒸发器气动声功率可行。     

往复式活塞压缩机中间喷液制冷系统的(火用)分析

通过对往复式活塞压缩机进行改造，在单级活塞压缩系统的基础上搭建了一种中间喷液冷却的准两级压缩系统并在蒸发温度为-20 ℃的工况下进行实验测量，根据实验数据对单级活塞压缩系统和新型中间喷液冷却活塞压缩系统的COP、〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗损失和〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗效率进行计算。结果表明：加入中间喷液冷却系统后，系统的COP由1.27提升至1.36，单位制冷量由155.1 kJ/kg提升至176.7 kJ/kg；单级活塞压缩系统〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗损失较大的部分是压缩机和膨胀阀，分别占压缩机输入〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗的16.2%和14.8%，加入中间喷液冷却系统后压缩机部分的〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗损失明显降低，仅占压缩机输入〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗的3.6%，冷凝器及膨胀阀的〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗损比也有所下降。