For the manufacture and assembly of the mechanical products, quality management is the key feature to improve the service performance, reduce the overall costs and enhance the sustainability of the manufacturing systems. While, with the emergence of advanced data-driven and digital twin technologies, the Zero-Defect Manufacturing (ZDM), which corrects, predicts, and prevents product defects based on multi-sources of data, is of great significance in improving assembly quality. As the specific application for the utilization of ZDM in product assembly, the critical performance index of the assembly results is predicted by taking into account the multi-source factors such as geometric deviation of the parts, material properties, assembly sequences and process boundary conditions during assembly. In this paper, we address the high computational cost and low computational efficiency of numerical simulation methods under multi-source factors, and propose a data-driven approach named DTA-VIT based on the fusion of heterogeneous variables for digital twin assembly modeling of products. Firstly, the geometric and performance variables of the assembly process are analyzed and modelled. Secondly, a multi-source assembly data fusion network under the Vision Transformer framework is developed. This network takes the parameter space, which fuses multi-source variables from the assembly process as input and the assembly result as output. Finally, a case study of the assembly process of composite bolted joint structures in aircraft assembly is conducted to verify the effectiveness and feasibility of the proposed method. The methodology provides a solid foundation for subsequent assembly quality control and prevent by predicting assembly performance efficiently, ultimately enabling the production of high-quality products.

Composite laminates, prized for their lightweight and high stiffness, are extensively used in aerospace and maritime applications. Bolted joints play a crucial role in connecting these laminates. However, assembly variations arise during the process, impacting performance due to material-related factors. To enhance analysis and aid material parameter design, this paper introduces a stress prediction framework, the BT-GAN (Bolted Tightening-GAN), which functions as a surrogate model employing a conditional generative adversarial network (cGAN) is designed to efficiently perform the forecasting task. This method effectively learns the physical mapping relationship between multiple parameters and the stress field, applying a graph generation approach to end-to-end predictions of the field. The model predicts stress fields under varying material parameters, compared with finite element methods and experimental results, validating the accuracy of the model. This framework improves understanding and facilitates efficient design in composite laminate assemblies with bolted joints.Keywords：Assembly analysis; Composite laminates; Bolted joints; Prediction of stress fields; Finite element analysis; Generative adversarial networks

The traditional physics laboratory has adopted a photogate and polarized light to measure rotation motion in a fixed system, but they are not applicable to rolling objects. Computer vision has played an increasingly important role in image analysis. The popularization of mobile phones, cameras and computers makes it possible to measure the rotation of an object in a simple but nonintrusive way in a physics laboratory. A 'tracker' has been used to analyze the rotation motion of large objects, such as vehicle wheels, by recognizing the position of a marker. However, it is still challenging to precisely recognize the marker in a small object via simple algorithms in a physics laboratory. In this paper, we introduce a facile image processing technique to visualize the rotation and spin motion of spheres by marking it with two red and green semi-spheres. A basic formula of projection was derived to analyze the expression of spin angles with the projection area of the semi-sphere. The precision and suitability of the image processing technique was proven to be effective through comparison with the photogate measurement technique. The image processing technique has also been used to analyze the rotation and spin motion of two spheres bonded with a rubber band. It provides not only the trajectory of sphere centers, but the evolution of spin angles, orbit diameter and orbit angles of spheres. By analyzing the relationship between spin angles and orbit diameter, it is clear that the rubber band experienced typical transformations between three different phases (twist, coil and supercoil) until the energy was exhausted. The method offers valuable insights into rotational dynamics, showcasing its potential for practical applications in the physics laboratory and in educational contexts.

Luminescent down-shifting (LDS) layer was introduced to tackle the issue of poor short-wavelength response of solar cell. Besides LDS effect, coating a LDS layer on the surface of a solar cell leads to a change in surface reflectance. LDS and antireflection (AR) effect are coupled and usually reported as a single effect. For those solar cell with optimized AR, it is difficult to enhance power conversion efficiency (PCE) with the LDS layer due to the variation of reflectance. In this work, we report an obvious PCE enhancement of two mainstream commercial silicon (Si) solar cells with the optimized AR by using methylammonium lead tribromide (MAPbBr3)/polymethyl methacrylate (PMMA) hybrid film as a LDS layer. The used MAPbBr3/PMMA nanoplatelets solutions for LDS layer have an absolute photoluminescent quantum yield of ∼85 % (excited by 350 nm) in air atmosphere for more than 30 days, laying a foundation for the realization of effective LDS effect. Theoretical analysis has separated the AR and LDS effect. It has demonstrated that AR effect has a positive influence on LDS effect, and PMMA plays the key role in the improvement of AR. Experimental studies further elucidated the LDS and AR effect provided by MAPbBr3/PMMA hybrid film. Thanks to this combined effect, the application of MAPbBr3/PMMA hybrid film as a LDS layer on Si heterojunction solar cell yields a PCE gain of 0.3 % absolute and that on passivated emitter and rear cell produces an absolute PCE enhancement of about 0.7 %.

The vertical and angular oscillation of a Wilberforce pendulum was found to be coupled in the case of resonance. Many studies have discussed the effects of the physical properties of a Wilberforce pendulum on coupled motion. In this article, we mainly study the influence of initial release conditions on the coupled motion of a Wilberforce pendulum in the near resonance case. The experimental results clearly exhibit that the coupled motion phenomenon depends on the initial release condition. Theoretical calculation further demonstrates that the coupled strength between two normal modes is determined by the ratio of initial angular to vertical displacement in the case of near resonance. The experimental results also verify the calculated variation of decoupling coefficient with this displacement ratio. Our study indicates that even in the case of resonance, the motion of a Wilberforce pendulum is probably decoupled at a given initial release condition. Complete decoupled motion is found to appear only when the damping coefficients in vertical and angular motion generate equal energy dissipation rates. The corresponding decoupling phenomenon in the case of resonance, occurs when the initial release energy of vertical and angular motion is equal.

根据脑科学的"双重编码"理论,可视化是一种发挥大脑视觉认知能力与空间计算能力的思维系统.在物理实验教学中应用物理演示实验、摄像同步教学的可视化教学手段,探讨可视化在物理实验教学中的效果.在教学实践中以声速测量实验为例开展研究,对周四上课学生采用演示实验和摄像同步教学,利用问题前测后测的方式反馈实验效果,并在实验后进行问卷调查;对周一上课学生未采用可视化教学手段,按照常规上课.从前测与后测问题反馈情况和学生调查问卷统计情况以及对照组实验最终成绩差异可以看出,合理使用可视化教学手段能促进物理实验教学效果,并得到学生普遍认可,表明这种可视化教学手段具有推广意义.

使用改装的双排换能器声速测量仪,根据时差法原理,利用示波器上的光标键测时间,不但能定性观察到声速在颗粒物质中相对于在空气中变小的现象,而且通过同步移动接收端换能器,还能测量出颗粒物质中与空气中的声速大小,定量比较得出颗粒物质中的声速比空气中的小.

物理实验中心是国家级实验教学示范中心,配合学校在本科教学中培养多学科交叉的复合型、创新型人才为教育目标,在实验课教学中积极研究、探索、引进多种先进的教学理念和教学方法.以"测量液氮比汽化热"这个有代表性的低温测量实验的教学过程为例,改进教学方法、拓展教学内容,以培养学生发现问题、解决问题、自主创新和动手能力,引导学生在进行基础实验的过程中主动观察、分析,找出对实验结果影响比较大的一些关键问题作为专题,指导学生继续研究、改进,从而真正地学到知识.并以液氮测量桶的内壁涂膜材料为专题研究对象,鼓励研制新装置,寻找合适的液氮测量桶,既激发了学生的学习热情,又取得了良好教学效果.

We perform combined x-ray tomography and shear force measurements on a cyclically sheared granular system with highly transient behaviors, and obtain the evolution of microscopic structures and macroscopic shear force during the shear cycle. We explain the macroscopic behaviors of the system based on microscopic processes, including particle level structural rearrangement and frictional contact variation. Specifically, we show how contact friction can induce large structural fluctuations and cause significant shear dilatancy effect for granular materials, and we also construct an empirical constitutive relationship for the macroscopic shear force.

目前各个高校都在积极开展"课程思政"建设,本文就上海交通大学大学物理实验教学与管理融入"课程思政"的探索略谈一二.首先分析了开展"课程思政"过程中存在的问题及解决的办法;其次以"声速测量实验"为例,展示了这种"思政元素"不突出的实验教学中如何融入"课程思政"元素;最后展示了如何在教学管理环节中融入"育人"功能.只要有"思政意识",思政教育不但可以融入实验教学,也可以融入实验教学管理中.

Methylammonium lead bromide (MAPbBr(3)) nanocrystals have attracted great attention for potential optoelectronic applications. We synthesized highly emissive MAPbBr(3) nanoplatelets (NPLs) by using a facile ligand assisted reprecipitation method with short-chain ligands. They exhibit an excitation-dependent photoluminescence (PL) quantum yield (QY) with a maximum value of 98% upon ultraviolet (UV) excitation. The femtosecond transient absorption and temperature-dependent PL spectra confirmed the existence of continuous band at similar to 350 nm and demonstrated that the PLQY of near unity originates from the efficient ultrafast energydown-shift from this band to exciton state in N phase, which quenches nonradiative recombination via trap states.

在传统的测量液氮比汽化热实验内容和方法的基础上,采用研究型教学方法,引导学生在实验中主动观察实验现象,发现液氮容器内液面高度对实验结果有较大影响.依靠国家教学示范中心的优质资源,学生重新制定实验方案,对实验内容做更进一步研究,用多块铜块集中对不同液面高度的液氮汽化情况分批测量,确定了测量液氮比汽化热时液氮容器内合适的液面高度区间.

Ligand-assisted reprecipitation (LARP) is a convenient and low-cost method to synthesize perovskite nanoplatelets (NPLs) with great optoelectronic properties. However, it still suffers from delicate purification and passivation. Here, we report the synthesis of perovskite NPLs via a simple one-step method through using chlorobenzene as poor solvent. These as-prepared NPLs exhibit good lateral-size homogeneity and emission wavelength tunability. Controlled experiment indicates that compared to the commonly used toluene, chlorobenzene is advantaged to enhance photoluminescence quantum yield (PLQY) and decay time of the perovskite NPLs. Raman spectra, x-ray photoelectron spectroscopy and energy dispersive spectra have shown that it is the passivation of chlorine atoms which suppresses nonradiative recombination and enhances PLQY. These results demonstrate that chlorobenzene is an alternative poor solvent to realize both the simplification of the LARP technique and the passivation of perovskite NPLs.

对恒力矩法测刚体转动惯量实验中存在的问题进行了分析和改进.从实验原理出发,重新分析了实验中转动惯量测量误差较大的原因,帮助学生从原理上了解实验操作中滑轮固紧调节、细绳走线方式以及角速度控制的最优方案.采用改进后的教学方法后,学生在实验中思路清晰,主动性增强,大部分学生的实验误差都能控制在5％ 之内,该实验教学收到了良好的教学效果.

对大学物理实验中集成霍尔传感器特性测量与应用实验的进行了改进.提出了用专门的螺线管测量灵敏度,使用2片正交放置的霍尔片测量待测通电螺线管中磁场磁感应强度,并给出了具体的测量步骤和电路设计以及测量结果.

通过对国外一流大学物理实验课程教学体系包括课程内容、教学方式和考核标准的调研,建立和物理理论课程讲授（授课对象以工科学生为主）相匹配的一整套可行的适应于工科创新拔尖人才培养的物理实验教学模式,包括项目设置、项目内容改革、考核方案、教学效果评价等.使得在工科同学理论课程知识点的学习中,物理实验能大大加深他们对物理概念的理解和掌握,同时物理实验将会增添他们学习物理理论的兴趣和学习效果.

Graphene oxide (GO) is a good candidate for high-performance humidity sensors with high responsitivity and rapid response. The GO sensoring mechanism is highly concerned and still not yet well understood. In this study, a systematic examination of GO capacitive humidity sensors was performed, revealing GO sensors' excellent sensitivity properties with two orders of capacitance change (within a relative humidity range of 12-97 RH%) and sub-0.1 s (tau(95)) response at room temperature being observed. A Fourier transform infrared technique was used to study the structural characteristics of GO films under both steady and transient humidity states. Interaction of water molecules with the functional groups in GO was detected, which induced evident changes of the GO structure and directly related to the sensoring processes. Free state liquid water was found to play an important role in the sensoring processes. A synergistic sensoring mechanism is suggested: functional groups work to reserve water and produce a larger layer space for better water transportation, while regions without functional groups work as effective channels for water transportation.

We present a comprehensive understanding of the nonlinear absorption characteristics of CdSe-based nanoplatelets (NPLs) synthesized by the solution-phase method and the colloidal atomic layer deposition approach through Z-scan techniques at 532 nm with picosecond pulses. The CdSe NPLs exhibit strong two-photon induced free carrier absorption (effective three-photon absorption) upon the nonresonant excitation, resulting in a remarkable optical limiting behavior with the limiting threshold of approximately 75 GW/cm2. A nonlinear optical switching from saturable absorption (SA) to reverse saturable absorption (RSA) with increasing the laser intensity is observed when coating CdSe NPLs with a monolayer of CdS shell to realize the resonant absorption. The SA behavior originates from the ground state bleaching and the RSA behavior is attributed to the free carrier absorption. These findings explicitly demonstrate the potential applications of CdSe-based NPLs in nonlinear optoelectronics such as optical limiting devices, optical pulse compressors and optical switching devices.

Carbon nanodots (C-dots) have attracted great attention for their biocompatibility and strong tunable photoluminescence (PL). However, aggregation-induced PL quenching blocks their practical application in solid-state optoelectronics. Here, we report a luminescent C-dots freestanding film with a substantially enhanced high quantum yield (QY) of 72.3%. A facile template method, rather than complicate lithography and etching technique is proposed to fabricate the C-dots composite films with large-area (8 inch × 8 inch) ordered micro-scale inverted-pyramid patterns on the surface. The control experiment and theoretical analysis demonstrate the key success to QY enhancement lies in the separation of C-dots and the pattern of surface inverted-pyramid structure. This work realizes the QY enhancement simply by geometrical optics, not the chemical treatment of luminescent particles. It provides a general approach to fabricate large-area freestanding luminescent composite film with high QY.