Ensemble deep transfer learning driven by multisensor signals for the fault diagnosis of bevel-gear cross-operation conditions

The existing intelligent fault diagnosis techniques of bevel gear focus on single-sensor signal analysis under the steady operation condition. In this study, a new method is proposed based on ensemble deep transfer learning and multisensor signals to enhance the fault diagnosis adaptability and reliability of bevel gear under various operation conditions. First, a novel stacked autoencoder(NSAE) is constructed using a denoising autoencoder, batch normalization, and the Swish activation function. Second, a series of source-domain NSAEs with multisensor vibration signals is pretrained. Third, the good model parameters provided by the source-domain NSAEs are transferred to initialize the corresponding target-domain NSAEs. Finally, a modified voting fusion strategy is designed to obtain a comprehensive result. The multisensor signals collected under the different operation conditions of bevel gear are used to verify the proposed method. The comparison results show that the proposed method can diagnose different faults in an accurate and stable manner using only one target-domain sample, thereby outperforming the existing methods.     

Development and experimental validation of an automatic parking brake system with less driveline sensor

Electrical Parking Brake (EPB) has been popularly used in passenger cars over the past ten years. With the help of the several kinds of sensors mounted in driveline for the total traction force estimation, EPB can obtain well performance on drive-off assistance and automatic parking brake. Furthermore, its AUTOHOLD function can realize automatic parking brake and ease the driver. However, given that the higher cost and complexity of this traction force estimation method based on the driveline sensors and its slower response resulted by applying maximum parking force for safety parking while driving off, a novel automatic parking brake system without these transmission system sensors, such as clutch position sensor for the cars with manual transmission, is proposed in this paper, including its control scheme and application test. Firstly, the indirect judgement method of the appropriate moment to release the parking brake, which is based on the car pitch moment when it drives off, is introduced according to the force analysis when the car is ready to go. Then a pragmatic mass estimation method for proper brake force calculation is proposed for improving the drive-off performance. In addition, for the convenience and drivability of skillful driver, as well as the system reliability, a mechanical redundant design to reserve the conventional handbrake lever is also described. Finally, various simulations based on CarSim software and road tests are performed to validate its effectiveness.     

上海世界博览会浦东西入口区设计

浦东西入口区位于世博会浦东园区西南隅，黄浦江在此折转向南。区内包括入口广场，滨江广场，世博塔和会议中心。西入口区既作为世博园区“山谷绿地”的西端对景，同时也将绿谷空间导向黄浦江。设计理念是致力表达中国山水柔美绵延的意向，展现科技与人文，人类与自然和谐共生的人居理想。该区机动交通系统有内环快速路，轻轨线及各类停车场。     

基于强度场的八球万向节内套结构与静强度设计匹配研究

为了对八沟道等速万向节内套进行结构和静强度设计,从钢球选型出发,对八沟道等速万向节内套进行了结构参数正向设计.对内套危险截面进行了全场静强度设计,以理想静强度场为目标,定量匹配了危险截面静强度的材料、热处理,并对全场静强度设计进行了定量评价.使用MTS静扭转试验机对等速万向节总成进行了静强度扭转试验,并用显微硬度计对内...     

The BEM based on conformal Duffy-distance transformation for three-dimensional elasticity problems

Science China Technological Sciences - Here, we describe the robust and efficient application of the conventional 3D BEM in solving elasticity problems. We have focused on the precise computation...     

Mg-Zn-Y-Nd coated with citric acid and dopamine by layer-by-layer self-assembly to improve surface biocompatibility

Magnesium alloy has been generally accepted as an important biodegradable material on cardiovascular stent development for a long time. However, its limited biocompatibility, especially delayed endothelialization process restricts its further application. In this contribution, we modified the Mg-Zn-Y-Nd alloy surface with citric acid and dopamine via a layer-by-layer self-assembly assay, aiming at improving the biocompatibility of the magnesium alloy. The citric acid/dopamine (CA/PDA) layer exhibited a remarkable suppression of platelet activation/aggregation and thrombosis under 15 dyn/cm² blood flowing. Inhibition on vascular smooth muscle cells growth and macrophages attachment/activation were also observed on this layer. In particular, the CA/PDA layer presented a promoted property for the vascular endothelial cells growth and spreading compared with the bare magnesium alloy, suggesting the pro-endotelialized function. In conclusion, this research may support potential application on surface modification of magnesium alloy based cardiovascular stents for better biocompatibility.     

计及可再生能源消纳的电热综合能源系统多目标优化模型

可再生能源因其清洁低碳的特点备受能源行业关注。但同时,可再生能源的不确定性也带来了严重的消纳问题。提高电力系统的灵活性去解决可再生能源的消纳问题成为当下研究热点之一。本文突破异质能源间的壁垒,基于电热综合能源系统去探索提高可再生能源的消纳能力。同时,立足于经济性与安全性指标,本文提出了一种多目标优化数学模型,并通过对偶转化和C CG算法对所提模型进行求解。最后,在算例测试中,通过对比电热综合能源系统与电力系统的各种测试指标证明了所提模型的有效性。     

基于小波有限元法的悬臂梁裂纹识别的试验研究

利用小波有限元法求解了裂纹悬臂梁的前三阶固有频率,并将其拟合成以裂纹位置和深度作为变量的固有频率解曲面;将实测的裂纹梁前三阶固有频率作为裂纹识别反问题的输入,绘制出各阶固有频率等高线,三条等高线的交点预测出裂纹存在的位置和深度。试验结果验证了算法的有效性,这为其实际应用提供了有力的试验依据。     

A feedback latching controller for two-body wave energy converters under irregular wave conditions

Latching control is considered to be an effective way to improve the energy absorption of a wave energy converter (WEC). Recently, a latching control method was realized in a hydraulic power take-off (PTO) system and was demonstrated to be effective in one-body WECs. However, the effectiveness of latching control for two-body WECs still needs to be tested. In this paper, a feedback latching controller is proposed for a conceptual two-body WEC. In this conceptual design, a permanent-magnet linear generator (PMLG) is adopted as the PTO system, and a pure water hydraulic cylinder system is designed for performing the latching control. A feedback control strategy based on the measurement of latching force is established, formulated and tested numerically under realistic irregular wave conditions. The effects of the wave peak period and the PTO damping coefficient on the effectiveness of the latching control is also investigated. The results indicate that the proposed feedback latching control is effective for improving the annual power absorption of the two-body WEC. Furthermore, compared to another latching control, the proposed control is more practical because it does not require any knowledge of the wave conditions or the dynamics of the whole WEC system.     

Experimental investigation on a novel liquid cooling device for a prismatic Li-ion battery module operating at high ambient temperature

Science China Technological Sciences - A novel liquid cooling device for a prismatic LiFePO4 battery module was proposed and manufactured in this study in order to improve the thermal management...