Direct Ink Writing of Highly Conductive MXene Frames for Tunable Electromagnetic Interference Shielding and Electromagnetic Wave?Induced Thermochromism

The highly integrated and miniaturized next-generation electronic products call for high-performance electromagnetic interfer?ence (EMI) shielding materials to ...     

Electrolyte/Structure?Dependent Cocktail Mediation Enabling High?Rate/Low?Plateau Metal Sulfide Anodes for Sodium Storage

As promising anodes for sodium-ion batteries, metal sulfides ubiquitously suffer from low-rate and high-plateau issues, greatly hindering their application in f...     

天车调度在优化钢厂物流管制中的重要作用

运用物流学中装卸搬运的知识,归纳了现代制造流程中运输环节的功能和作用,分析了炼钢厂物流系统中天车作业的特点,并对钢厂时间因素和生产工艺进行了研究与分析,从中可知天车调度在优化钢厂物流管制中的重要作用。     

Investigation into the InAs/GaAs quantum dot material epitaxially grown on silicon for O band lasers

InAs/GaAs quantum dot(QD)lasers were grown on silicon substrates using a thin Ge buffer and three-step growth method in the molecular beam epitaxy(MBE)system.In addition,strained superlattices were used to prevent threading disloca-tions from propagating to the active region of the laser.The as-grown material quality was characterized by the transmission electron microscope,scanning electron microscope,X-ray diffraction,atomic force microscope,and photoluminescence spectro-scopy.The results show that a high-quality GaAs buffer with few dislocations was obtained by the growth scheme we de-veloped.A broad-area edge-emitting laser was also fabricated.The O-band laser exhibited a threshold current density of 540 A/cm² at room temperature under continuous wave conditions.This work demonstrates the potential of large-scale and low-cost manufacturing of the O-band InAs/GaAs quantum dot lasers on silicon substrates.     

热机械疲劳寿命的应变唯象描述

通过比较热机械疲劳寿命的3种不同唯象描述方法,讨论了相位差对疲劳寿命的影响,提出对疲劳寿命的唯象描述应采用总应变范围Δε_t或非弹性应变范围Δε_in,才符合工况模拟试验和疲劳寿命预测的基本条件。     

Path Planning and Tracking Control for Parking via Soft Actor-Critic Under Non-Ideal Scenarios

Parking in a small parking lot within limited space poses a difficult task. It often leads to deviations between the final parking posture and the target posture. These deviations can lead to partial occupancy of adjacent parking lots, which poses a safety threat to vehicles parked in these parking lots. However, previous studies have not addressed this issue. In this paper, we aim to evaluate the impact of parking deviation of existing vehicles next to the target parking lot(PDEVNTPL) on the au...     

带圆孔的薄壁管多轴向低周疲劳性能的判据

在40Cr钢制成的带圆孔的薄壁管上进行拉-扭双向的低周疲劳试验,并用弹塑性有限元方法分析试件圆孔区域应力和应变分布。通过对以前的多轴向疲劳准则的分析研究,根据薄壁管拉-扭双向疲劳的试验和理论分析的结果,提出了一个新的多轴向应力疲劳的判据。它可以比较好地预测疲劳起裂寿命和裂纹位置。     

Magnetic Field-Based Reward Shaping for Goal-Conditioned Reinforcement Learning

Goal-conditioned reinforcement learning (RL) is an interesting extension of the traditional RL framework, where the dynamic environment and reward sparsity can cause conventional learning algorithms to fail. Reward shaping is a practical approach to improving sample efficiency by embedding human domain knowledge into the learning process. Existing reward shaping methods for goal-conditioned RL are typically built on distance metrics with a linear and isotropic distribution, which may fail to provide sufficient information about the ever-changing environment with high complexity. This paper proposes a novel magnetic field-based reward shaping (MFRS) method for goal-conditioned RL tasks with dynamic target and obstacles. Inspired by the physical properties of magnets, we consider the target and obstacles as permanent magnets and establish the reward function according to the intensity values of the magnetic field generated by these magnets. The nonlinear and anisotropic distribution of the magnetic field intensity can provide more accessible and conducive information about the optimization landscape, thus introducing a more sophisticated magnetic reward compared to the distance-based setting. Further, we transform our magnetic reward to the form of potential-based reward shaping by learning a secondary potential function concurrently to ensure the optimal policy invariance of our method. Experiments results in both simulated and real-world robotic manipulation tasks demonstrate that MFRS outperforms relevant existing methods and effectively improves the sample efficiency of RL algorithms in goal-conditioned tasks with various dynamics of the target and obstacles.

     

Discussion of the Constitutive Relation on Cyclic Stress-Strain of Engineering Materials

Based on the experimental results and analysis of the cyclic deformation, there is an obvious yield stage on the cyclic stress-strain curve at the stage of small plastic deformation （in room or low temperatures）. This phenomenon is similar to that of monotonic tensile curve case. But for the former the deformation amount at which the yield begins is much smaller than that for the latter. The cyclic stress-strain constitutive relation needs to be further studied according to the actual cyclic stress-strain curve. The conventional constitutive equation σ=Aεⁿ is based on the results only corresponding to the cyclic strengthening stage. It is not appropriate for the stage of the small plastic deformation and the stage of yield.     

一种基于区块链的隐私保护异步联邦学习

在联邦学习作为隐私保护技术被广泛应用的同时,也产生了中心服务器不稳定和联邦学习服务器与参与方交互造成的隐私泄露等新的挑战及安全问题. 提出了一种基于区块链和动态评估的隐私保护联邦学习模型,利用区块链解决中心服务器的问题,通过本地训练使用稀疏化、全局模型更新使用差分隐私解决联邦学习过程中的隐私泄露问题,本地训练完成后用数字签名和双重Hash对比验证参与方身份和训练模型的所属权. 此外,使用多权重动态评估方法计算单轮模型和参与方评估值作为参与方贡献的依据. 实验结果表明,提出的模型可以有效解决联邦学习中的单点故障和局部模型验证问题,与传统联邦学习相比,使用稀疏化和差分隐私可以在略微损失准确率的情况下保障模型的安全性,并有效地为参与方进行评估,从而保证了激励机制的公平性.