INTEGRAL THEORY FOR THE DYNAMICS OF NONLINEAR NONHOLONOMIC SYSTEM IN NONINERTIAL REFERENCE FRAMES

This paper establishes the integral theory for the dynamics of nonlinear nonholonomic system in noninertial reference frame. Firstly, based on the Routh equation of the relative motion of nonlinear nonholonomic system gives the first integral of the system. Secondly, by using cyclic integral or energy integral reduces the order of the equation and obtains generalized Routh equation and Whittaker equation respectively. Thirdly, derives canonical equation and variation equation and by using the first integral constructs integral invariant. And then, establishes the basic integral variants and the integral invariant of Poincare-Cartan type. Finally, we give a series of deductions.

FIRST INTEGRALS AND INTEGRAL INVARIANTS FOR VARIABLE MASS NONHOLONOMIC SYSTEM IN NONINERTIAL REFERENCE FRAMES

The first integrals and their conditions of existence for variable massnonholonomic system in noninertial relerence frames are obtained,and the canonicalequations and the variation equations of the system are extended. It is proved that using the first integral we can construct the integral invariant of the system.Finally,a series of deductions and an example are given.

Novel Frame Shift and Integral Technique for Enhancing Low-Light-Level Moving Images

A novel frame shift and integral technique for the enhancement of low light level moving image sequence is introduced. According to the technique, motion parameters of target are measured by algorithm based on difference processing. To obtain spatial relativity, images are shifted according to the motion parameters. As a result, the processing of integral and average can be applied to images that have been shifted. The technique of frame shift and integral that includes the algorithm of motion parameter determination is discussed, experiments with low light level moving image sequences are also described. The experiment results show the effectiveness and the robustness of the parameter determination algorithm, and the improvement in the signal-to-noise ratio （SNR） of low light level moving images.

Integrated design optimization of composite frames and materials for maximum fundamental frequency with continuous fiber winding angles

Fiber reinforced composite frame structure is an ideal lightweight and large-span structure in the fields of aerospace,satellite and wind turbine.Natural fundamental frequency is one of key indicators in the design requirement of the composite frame since structural resonance can be effectively avoided with the increase of the fundamental frequency.Inspired by the concept of integrated design optmization of composite frame structures and materials,the design optimization for the maximum structural fundamental frequency of fiber reinforced frame structures is proposed.An optimization model oriented at the maximum structural fundamental frequency under a composite material volume constraint is established.Two kinds of independent design variables are optimized,in which one is variables represented structural topology,the other is variables of continuous fiber winding angles.Sensitivity analysis of the frequency with respect to the two kinds of independent design variables is implemented with the semi-analytical sensitivity method.Some representative examples in the manuscript demonstrate that the integrated design optimization of composite structures can effectively explore coupled effects between structural configurations and material properties to increase the structural fundamental frequency.The proposed integrated optimization model has great potential to improve composite frames structural dynamic performance in aerospace industries.

An Integration Framework for Digital Progressive Die Design and Manufacturing

This paper reports an effort to develop an intelligent integration framework for digital progressive die design and manufacturing. Both data-and process-centric integration functions are provided by the framework as if a special ight-weight PDM/PLM (Product Data Management/Product Lifecycle Management) and WM (Workflow Management) system is embedded in the integrated engineering environment. A flexible integration approach based on the CAD (Computer-Aided Design) framework tenet is employed to rapidly build up the system while the intrinsic characteristics of the process are comprehensively taken into account. Introduction of this integration framework would greatly improve the dynamic performance of the overall progressive die design and manufacturing process.

引线框架用高性能铜合金板带材及制备工艺

电子信息产业的飞速发展,对铜及铜合金产品性能提出了更高的要求,其中集成电路封装用引线框架材料代表了铜合金板带材发展的较高水平。本文对近年来引线框架用高性能铜合金板带材及制备工艺进行了综述,介绍了国内外高性能铜合金板带材料的成分和制备加工技术及发展过程,并对其未来发展趋势进行了展望,提出未来高性能铜板带材性能将朝着抗拉强度为700 MPa、导电率为70%IACS的目标发展,其制备工艺将向着智能化、绿色化、高效化等方向发展。

一种世界坐标系下的GNSS/SINS松组合导航矩阵李群滤波算法

针对在地心地固(ECEF)坐标系下基于右不变误差的卡尔曼滤波在GNSS/SINS组合导航中,因位置矢量数值较大导致系统线性误差运动学矩阵和观测矩阵不稳定进而降低滤波器性能的问题,提出一种世界坐标系下的GNSS/SINS松组合导航矩阵李群滤波算法。首先在世界坐标系中构建导航状态和考虑地球自转的运动学方程。然后在世界坐标系下定义矩阵李群上的右不变误差,该误差在右群作用下保持不变,并重新推导和设计基于该误差的矩阵李群滤波算法,根据GNSS观测构建世界坐标系下的观测矩阵。实验结果表明,在低精度惯导场景中相对于ECEF坐标系下的传统扩展卡尔曼滤波,所提算法的北向、东向、地向位置误差均方根分别减小了82.6%、61.8%和10.6%,具有一定的实用价值。

机械系统动力学案例思政融合设计探索

通过梳理机械系统动力学课程的主要内容,从三个角度四个方面设计15个案例,形成多层级的教学案例体系。通过在广义系统动力学和动力学仿真案例中融入世界观和方法论,并用单自由度系统动力学案例融入同频共振人生观,用多自由度系统动力学案例融入合作共赢价值观,形成三横四纵的课程思政体系。将学生的三观塑造和能力提升自然而然地融入教学案例,实现课程思政与教学案例的成体系融合。

基于异构集成模型的连续刚构桥预拱度预测

预拱度在大跨度悬臂桥梁的施工线形监控中扮演着重要角色,提高预测精度能够确保施工阶段和成桥状态的线形尽可能符合设计要求。为获得更好的预测性能,本文提出了一种基于自适应集合加权的SSA-BPNN-RF(sparrow search algorithm-back propagation neural network-random forest)异构集成模型。该模型利用不同算法之间的协作来提高预测性能,为了验证该模型的可行性,将训练好的模型应用于湖南某连续刚构桥预拱度预测,并与BPNN、RF、BPNN-RF、SSA-BPNN和SSA-RF 5种预测模型进行对比。研究结果表明:SSA-BPNN-RF异构集成模型在平均绝对误差、均方根误差和拟合度等评价指标上表现最佳。此外,BPNN-RF集成和SSA分别对BPNN和RF都有积极的影响,进一步验证了异构集成的有效性。因此,SSA-BPNN-RF异构集成模型具有高精度和更好的适应性,在工程实践中具有重要的指导意义。

正常体质量与超体质量乳腺癌患者改良根治术后不同固定方式放射治疗摆位误差分析

目的探讨正常体质量和超体质量乳腺癌患者使用乳腺托架和一体化体架2种不同固定方式对分次放射治疗(放疗)摆位误差的影响。方法回顾性分析2021年8月-2022年8月86例行乳腺癌改良根治术后接受放疗的乳腺癌患者的临床资料,其中使用乳腺托架的正常体质量和超体质量患者各15例,使用一体化体架的正常体质量和超体质量患者各28例,记录患者在X、Y和Z轴方向上的5组分次间定位数据,分析正常体质量与超体质量患者使用2种不同固定方式的分次摆位误差。结果(1)正常体质量和超体质量患者使用乳腺托架和一体化体架的摆位误差比较,仅有正常体质量患者在Z方向上摆位误差的差别有统计学意义(P=0.021),其他方向上摆位误差的差别均无统计学意义(P>0.05)。(2)正常体质量患者使用乳腺托架时,在Z方向上的第1次摆位误差大于其他分次;在使用一体化体架时,在Y方向和Z方向上的第1次摆位误差大于其他分次,差别均有统计学意义(P<0.05)。(3)超体质量患者使用乳腺托架时,在Y方向上的第1次摆位误差大于其他分次,差别均有统计学意义(P<0.05);在使用一体化体架时,在X、Y和Z方向第1次摆位误差均大于其他分次,Z方向首次摆位误差与其他分次间的差别有统计学意义(P<0.05)。结论一体化体架可以在一定程度上代替乳腺托架以减少时间成本,但乳腺托架具有较小的分次间误差。对超体质量患者推荐使用乳腺托架。

基于力控技术的航空整体加强框自适应定位方法研究

为了减弱制造差异对航空整体加强框装配定位质量的影响,解决强迫定位造成的定位过程管控性差和定位结果复现度低的难题,基于力控技术提出一种航空整体加强框自适应定位方法,按传统强迫方式完成装配定位后,在设计允许范围内调整若干坐标定位孔位置,至孔位处力载值满足自适应定位要求。针对航空整体加强框装配定位工艺对形位精度、装配应力水平的要求,量化装配定位质量评价标准,基于正交试验分析定位孔处力载绝对平均值和定位检测点处应力绝对平均值的变化规律,进行装配现场易于获取的力载值取代应力值的可行性研究,通过修正装配定位质量评价标准量化公式得到坐标定位孔处力载调整目标,指导航空整体加强框装配定位。

近断层地震作用下高速铁路大跨连续刚构桥易损性研究

为探究近断层地震作用下高速铁路大跨连续刚构桥的抗震性能,基于工程需求(EDP)符合对数高斯分布假设获取全桥损伤曲线,提出一种桥梁地震损伤危险性分级方法。在此基础上,考虑桥上无砟轨道的刚度效应,采用OpenSees有限元软件建立了某高速铁路大跨连续刚构桥的轨道-桥梁(线-桥)一体化非线性有限元模型;由80条近断层地震动实录波组成地震动数据库,采用基于概率需求的易损性分析方法详细分析了该高速铁路大跨连续刚构桥的抗震性能。结果表明:对于研究计算条件,近断层地震动速度峰值(PGV)与工程需求间的相关性较强;近断层地震作用下高速铁路连续刚构桥的边支座易出现轻微损伤,当遭遇中高强度(PGV>100 cm/s)近断层地震动时桥梁关键截面的屈服概率较大,当PGV为200 cm/s时桥梁结构会受到严重破坏,而当PGV为300 cm/s时桥梁有极大可能发生完全破坏甚至出现倒塌。研究成果可为近断层区域高速铁路连续刚构桥的抗震设计提供参考。

小曲线高速铁路预制箱梁运架施工技术研究

为解决小曲线箱梁运架施工困难及传统架桥机易倾覆、稳定性差问题,对传统架桥机前支腿及控制系统进行了改进,从而满足曲线箱梁架设和架桥机过孔的需求。基于高精度传感设备构建了架桥机安全监测系统,对箱梁架设过程进行动态监测分析。研究结果表明,预制箱梁架设过程中架桥机具有较强的稳定性及安全储备,支腿水平度均稳定在5‰以内,支腿应力均小于容许应力,满足规范要求,实现了小曲线高速铁路预制箱梁的快速、安全运架一体化作业,可为同类工程提供一定的参考借鉴。

面向6G通感一体的关键技术研究

近年来通感一体在未来网络中的应用前景愈趋明朗,聚焦通感信道建模、波形与帧结构设计和协作感知三大关键问题,分别梳理最新研究进展,提出潜在解决方案。首先基于当前标准进展,提出涵盖大小尺度衰落和目标反/散射的分段级联通感信道统计模型;接着面向连续感知覆盖需求,开展支持组合波形、多双工模式感知的通感帧结构优化设计;最后,面向多点协作,基于干扰抑制的动态基站选择策略,提出协作感知算法。

超高重型大跨度室内滑雪场钢屋盖建造技术

网架作为一种空间杆系结构,因其具有整体性和稳定性好、空间刚度大和抗震性能好的优点而被广泛应用在大跨度结构中。常规的网架安装方法主要有整体提升法、高空滑移法、分条吊装法及高空散装法等。但超高重型焊接球网架不同于一般螺栓球网架,其跨度及可承受的荷载更大,对应的施工安装难度及安全风险更高,如果仅采用单种常规安装方法,很难高效、顺利地实现结构成型。以上海临港冰雪之星项目室内滑雪场钢屋盖为背景,着重介绍“原位原姿态拼装后分块整体提升”的安装技术路线及对应施工过程分析和改进措施,并通过对胎架拼装、提升控制及卸载等关键工序的研究,为今后类似大跨度钢结构屋盖安装的施工方案提供参考。

Preservation Strategies of Timber-framed Arch Bridges as Cultural Landscape Heritage

Theoretical study on and safeguarding of cultural landscape heritage has been put on the agenda of heritage protection in Zhejiang and Fujian provinces.The safeguarding of timber-framed arch bridge heritage in the past 5 decades could be classified into 3 stages,and heritage protection in all 3 stages was closely related to original meaning of "landscape",which proved that timber-framed arch bridge heritage had profound inside information,and the safeguarding of timber-framed arch bridge from the perspective of cultural landscape heritage was worth further study.Safeguarding of timber-framed arch bridge cultural landscape heritage focused on integrated conservation,but not protection of individual bridges.Integrated conservation of world heritage is to maintain and restore the integrated environment landscape of the heritage,thus protection of timber-framed arch bridge heritage is not only to explore its architectural craftsmanship,but also to lay a foundation for the dynamic succession of such craftsmanship as intangible cultural heritage.Value of the existing timber-framed arch bridges as historic building heritage was discussed,and it was proposed that ultimate objectives of the safeguarding could be realized step by step from 3 layers.

基于一体式导向架的大直径钢护筒水上快速施工技术

海南铺前大桥跨越3条地震断裂带,是国内唯一一座跨越活动断裂带的跨海特大桥。考虑抗震需求,针对跨断层、近断层桥墩,尤其是主桥墩这类斜拉桥关键受力结构物,采用了φ4.3 m钢管复合桩。从大直径钢护筒运输、沉放及质量控制等方面进行了系统的研究。一方面为海南铺前大桥大直径永久钢护筒以及其余海上桩基钢护筒提供施工依据,保证了大直径钢护筒快速、精确沉放,满足了设计及规范要求;另一方面完善了水上大直径钢护筒快速精确沉放的理论。

建筑外墙框架体系一体化系统研发与应用

研发了新型建筑外墙框架体系一体化系统,并研究不同砌筑粘结砂浆对系统界面粘结性能的影响,分析了系统功能性、耐久性及应用技术。结果表明,普通、薄层、保温砌筑粘结砂浆在硅墨烯改性聚苯保温板与蒸压加气混凝土砌块同时砌筑时的系统拉伸粘结强度,相比其与硅墨烯改性聚苯保温板的拉伸粘结度分别提高了128.6%、35.3%、100.0%。另一方面,使用薄层、保温砌筑粘结砂浆能够明显改善砌体的通缝抗剪强度和系统拉伸粘结强度等性能,进一步提高墙体系统的稳定性和抗开裂性。

大直径筒仓仓顶结构施工对比分析

近年来,我国粮食生产连年丰收,粮食安全总体有保障,因此各地粮仓加速建设,以满足粮食储备要求。大直径浅圆仓锥形仓顶模板支撑因其大跨度、超高等施工难度大、危险系数高、难以一次性浇筑实现等诸多问题存在使用局限。以某粮食仓储项目为背景,细致分析大直径筒仓仓顶结构施工的两种空中支撑平台,为今后类似工程项目施工提供参考。

关于掘锚一体机截割装置滑移架的拓扑优化研究

以JM340型掘锚一体机截割装置中的滑移架为研究对象,基于先进的拓扑优化技术和HYPERWORKS有限元软件对滑移架进行优化改进。拓扑优化结果表明,滑移架的拓扑数值存在很大差异,说明工作时不同区域的受力表现出不均匀性的特点。通过在立板两侧设置加强筋、掏槽油缸连接座箱体区域设置加强筋、去除导轨套筒连接箱体中间区域材料的方式进行结构优化,优化后的滑移架重量降低3%。通过累计1年时间的应用,发现滑移架具有良好的运行稳定性,可提升其使用寿命。