Design methodology of a mini-missile considering flight performance and guidance precision

The design of mini-missiles(MMs)presents several novel challenges.The stringent mission requirement to reach a target with a certain precision imposes a high guidance precision.The miniaturization of the size of MMs makes the design of the guidance,navigation,and control(GNC)have a larger-thanbefore impact on the main-body design(shape,motor,and layout design)and its design objective,i.e.,flight performance.Pursuing a trade-off between flight performance and guidance precision,all the relevant interactions have to be accounted for in the design of the main body and the GNC system.Herein,a multi-objective and multidisciplinary design optimization(MDO)is proposed.Disciplines pertinent to motor,aerodynamics,layout,trajectory,flight dynamics,control,and guidance are included in the proposed MDO framework.The optimization problem seeks to maximize the range and minimize the guidance error.The problem is solved by using the nondominated sorting genetic algorithm II.An optimum design that balances a longer range with a smaller guidance error is obtained.Finally,lessons learned about the design of the MM and insights into the trade-off between flight performance and guidance precision are given by comparing the optimum design to a design provided by the traditional approach.

Precise Design and Stress Analysis of Straight Conical Gear

Variable section sweeping with sphere involutes is used to generate the precise model of tooth profile. The contact and bending stress of a straight conical gear set with static bearing contact during a meshing cycle is studied using finite element method. Numerical results and comments are presented, revealing that the edge contact causes stress concentration and the gear tooth profile needs further modification.

Precision Design for Machine Tool Based on Error Prediction

Digitization precision analysis is an important tool to ensure the design precision of machine tool currently. The correlative research about precision modeling and analysis mainly focuses on the geometry precision and motion precision of machine tool, and the forming motion precision of workpiece surface. For the machine tool with complex forming motion, there is not accurate corresponding relationship between the existing criterion on precision design and the machining precision of workpiece. Therefore, a design scheme on machine tool precision based on error prediction is proposed, which is divided into two-stage digitization precision analysis crucially. The first stage aims at the technology system to complete the precision distribution and inspection from the workpiece to various component parts of technology system and achieve the total output precision of machine tool under the specified machining precision; the second stage aims at the machine tool system to complete the precision distribution and inspection from the output precision of machine tool to the machine tool components. This article serves YK3610 gear hobber as the example to describe the error model of two systems and basic application method, and the practical cutting precision of this machine tool achieves to 5-4-4 grade. The proposed method can provide reliable guidance to the precision design of machine tool with complex forming motion.

Die design for cold precision forging of bevel gear based on finite element method

The finite element analysis （FEA） software Ansys was employed to study the stress state of the dies of both plane and non-plane parting face structures with uniform interference and the die of plane parting face structure with non-uniform interference. Considering the symmetry of the die, a half gear tooth model of the two-ring assembled die with 2.5 GPa inner pressure was constructed. Four paths were defined to investigate the stress state at the bottom comer of the die where stress concentration was serious. FEA results show that the change of parting face from non-plane to plane can greatly reduce the stress at the teeth tips of the die so that the tip fracture is avoided. The interference structure of the die is the most important influencing factor for the stress concentration at the bottom comer. When non-uniform interference is adopted the first principal stress at the comer on the defined paths of the die is much lower than that with uniform interference. The bottom hole radius is another important influencing factor for the comer stress concentration. The first principal stress at the comer of the plane parting face die with non-uniform interference is reduced from 2.3 to 1.9 GPa when the hole radius increases from 12.5 to 16.0 mm. The optimization of the die structure increases the life of the die from 100 to 6 000 hits.

Dynamic Accuracy Design Method of Ultra-precision Machine Tool

Ultra-precision machine tool is the most important physical tool to machining the workpiece with the frequency domain error requirement, in the design process of which the dynamic accuracy design(DAD) is indispensable and the related research is rarely available. In light of above reasons, a DAD method of ultra-precision machine tool is proposed in this paper, which is based on the frequency domain error allocation.The basic procedure and enabling knowledge of the DAD method is introduced. The application case of DAD method in the ultra-precision flycutting machine tool for KDP crystal machining is described to show the procedure detailedly. In this case, the KDP workpiece surface has the requirements in four different spatial frequency bands, and the emphasis for this study is put on the middle-frequency band with the PSD specifications. The results of the application case basically show the feasibility of the proposed DAD method. The DAD method of ultra-precision machine tool can effectively minimize the technical risk and improve the machining reliability of the designed machine tool. This paper will play an important role in the design and manufacture of new ultra-precision machine tool.

Investigation into precision engineering design and development of the next-generation brake discs using Al/SiC metal matrix composites

Substantially lightweight brake discs with high wear resistance are highly desirable in the automotive industry.This paper presents an investigation of the precision-engineering design and development of automotive brake discs using nonhomogeneous Al/SiC metal-matrixcomposite materials.The design and development are based on modeling and analysis following stringent precision-engineering principles,i.e.,brake-disc systems that operate repeatably and stably over time as enabled by precision-engineering design.The design and development are further supported by tribological experimental testing and finite-element simulations.The results show the industrial feasibility of the innovative design approach and the application merits of using advanced metal-matrix-composite materials for next-generation automotive and electric vehicles.

The Relationship between Interchangeability Standards and Precision Design in Teaching a Course on Interchangeability and Measurement Techniques

This article discusses some views on the relationship between carrying out and applying standards and precision design and the teaching of a course on interchangeability and measurement techniques. It points out that while emphasizing precision design, we should not underrate the significance of interchangeability and standardization. Although there are presently many teaching models available for such courses, each course should be designed separately to preserve its systematic character and integrality. As well, the development of students' abilities in precision design and the application of standards should be strengthened in experimental lessons within each course.

Forming-Precision-Driven Structure Design of Hydraulic Press: Methodology and Case Study

The structure stiffness of presses has great effects on the forming precision of workpieces, especially in near-net or net shape forming. Conventionally the stiffness specification of presses is empirically determined, resulting in poor designs with insufficient or over sufficient stiffness of press structures. In this paper, an approach for the structure design of hydraulic presses is proposed, which is forming-precision-driven and can make presses costeffective by lightweight optimization. The approach consists of five steps:(1)the determination of the press stiffness specification in terms of the forming precision requirement of workpieces;(2)the conceptual design of the press structures according to the stiffness and workspace specifications, and the structure configuration of the press;(3)the prototype design of the press structures by equivalently converting the conceptual design to prototypes;(4)the selection of key structure parameters by sensitivity analysis of the prototype design; and(5)the optimization of the prototype design. The approach is demonstrated and validated through a case study of the structure design of a 100 MN hydraulic press.

Effective tool design of three-rank form as precision removal-process of ITO thin-films

A new effective tool design of three-rank form of electroremoval was present using a precision recycle system offering faster performance in removing the indium-tin-oxide(ITO) thin-films on color filter surface of displays. Higher electric power is not required since the three-rank form tool is adopted as a feeding mode to reduce the response area. The low yield of ITO persists throughout the entire semiconductor production process. By establishing a recycle process of ultra-precise removal of the thin-film nanostructure, defective products in the optoelectronic semiconductors industry can be effectively recycled, decreasing both production costs and pollution. A 5th generation TFT-LCD was used. The design features of the removal processes for the thin-films and the tool design of three-rank form were of major interest. For the precision removal processes, a pulsed current can improve the effect of dreg discharge and contributes to the achievement of a fast workpiece (displays' color filter) feed rate, but raises the current rating. High flow velocity of the electrolyte with a high rotational speed of the tool electrodes elevates the ITO removal effect. A displays' color filter with a fast feed rate is combined with enough electric power to provide highly effective removal. A small thickness of the rank and a small arc angle of the negative-electrode correspond to a higher removal rate for ITO-film. An effective three-rank form negative-electrode provides larger discharge mobility and better removal effect. It only needs a short period of time to remove the ITO easily and cleanly.

精准更新导向下的数字化城市设计实践探索——以上海市陆家嘴水环为例

本研究面向精准更新需求,提出了数字化城市设计分析范式,推动设计分析与效能评估从主观经验向量化解析的转换。在现状问题研判上以“人本”为核心,基于移动互联网LBS数据解析场地人口组成与行为特点,基于路网组构和sDNA诊断慢行堵点断点,基于美团与微博数据研判空间品质,基于结构化网页数据与POI兴趣点数据提炼功能布局,在方案效能评估上强调“量化”,结合大数据案例库与空间分析技术形成针对性效能提升分值评价。陆家嘴水环片区,这一紧邻上海核心CBD的“城市背面”,作为具有更新潜力和复合问题的代表性区域被选为案例。通过多源城市数据和城市设计分析技术的城市体检,本研究在实现从问题诊断到效能评估的多环节嵌入性支持的同时保证了相关分析方式的可推广性。通过实践需求引导下的技术与设计深度融合,本文有望为设计科学(Design Science)新范式的涌现提供针对性探索。

寒地黑土区水稻秸秆还田机设计及最优耕作参数试验

针对寒地黑土区水稻秸秆还田机消耗功率大、秸秆腐解速度慢的问题,设计具有腐解剂精量喷施功能的秸秆还田机,并探究刀轴扭矩最小时的耕作参数组合。对还田机的自动升降平地装置、菌剂喷洒装置、秸秆量识别系统和还田弯刀进行设计:菌剂喷洒装置采用由PLC驱动的电磁阀控制喷施量;秸秆量识别系统可分别对粉碎堆积秸秆和留茬秸秆进行数量评估并将数据信息传递至菌剂喷洒装置;还田弯刀设计采用Workbench 2022 R1软件进行仿真分析,得到弯刀最佳参数结果:弯刀刃长240 mm、刃宽80 mm、弯折角115°;采用三因素三水平旋转正交试验,建立刀轴扭矩与试验因素的关系。采用Design-Expert软件进行方差分析处理,结果表明,因素对指标影响的顺序关系为:耕深>旋转速度>单位面积秸秆量>耕深的二次项>耕深与旋转速度的交互作用>旋转速度与单位面积秸秆量的交互作用,并得到交互作用的响应曲面图以及最优参数组合为耕深20 cm、旋转速度为240 r/min、单位面积秸秆量为3.5 kg/m^(2)。进行验证性试验,得到扭矩平均值为24.32 N⋅m,与模型预测值的相对误差为0.7%,预测模型可靠,且秸秆翻埋率达96.8%。

精准时代下住院医师规范化培训方法初探

随着整个社会“精准”理念的不断提出,精准时代的概念逐渐形成,而互联网、大数据、人工智能等的快速发展也为精准理念提供了更有力的保障。住院医师规范化培训以立德树人为引导,以培养岗位胜任力为目标,教与学都要力争“精准”。因此,可以将“精准医学”“精准教学”等理论体系引入住院医师规范化培训中,针对不同的学员层次制订精准合理的教学目标和个体化教学方案,对学生的基本信息和既往学习背景进行全面了解、分析,从而精准把控学情。结合实际,有针对性地组织教学资源和设计教学活动,并动态优化教学进程,保证教学质量。借助大数据、手机APP等智能手段对教学效果进行全方位复合评价,从而精准分析、改进教学方案。通过全维度精准培训,做到因材施教、人尽其才,为培养全方位的医学人才提供有力保障。

4行气吸式马铃薯原原种精量播种机设计

马铃薯原原种的繁育最早由人工种植,其生产成本高,不利于规模化生产。基于原原种的种植农艺要求、种子物理性状和耕作种床条件等情况,进行了4行气吸式马铃薯原原种精量播种机的研究设计。通过台架和田间试验得到,该播种机的操作性能、播种精度和质量都满足种植的农艺要求,实现了马铃薯原原种机械化精量播种作业。

高压自紧式聚酰亚胺垫片密封性能影响因素分析及结构优化

为了解决液体火箭发动机在异常工况下的密封失效问题,建立了发动机充气阀阀芯密封结构的有限元模型,分析了密封结构参数、加工误差及卡滞偏斜对充气阀阀芯密封性能的影响,并进行了试验验证。结果表明:综合考虑可加工性、密封效果,圆阀座是充气阀的首选结构;在不同圆角半径下,圆角半径在0.35~0.45 mm范围内使用效果最佳;平面度偏差及卡滞偏斜在0~0.07 mm范围内对密封效果和使用寿命几乎没有影响。本研究可为航天军工用高精密密封的设计和优化提供参考,有助于提高我国高精密密封的技术水平。

气辅成型工艺参数正交精准设计优化

“双碳”目标下,气辅成型技术为塑料成型实现降低碳排放提供了有效途径。为精准规划气辅成型参数,提升气辅成型质量和效率,有效降低碳排放,采用三维数值模拟和成型实验,研究参数交互作用下气辅成型工艺正交优化。结果表明,参数交互作用对气体穿透长度影响小,而对气指缺陷的影响显著。极差分析的基础上,获得了优选参数组:熔体温度240℃,注气压力3 MPa,延迟时间4 s,模具温度40℃。经数值模拟和成型实验验证,优选参数组下得到气辅塑件的气体穿透长度及气指指标优良,可用于气辅成型实际生产。

智能精密播种机的优化设计

智能精密播种机是一种自动化的农业设备,可大幅提高种植效率、减少种植成本。但是,目前智能精密播种机依赖高精度的传感器、控制系统和算法来实现准确的种子投放和深度控制,需要较高的技术要求和技术支持,且对于一些不规则形状的种子或大粒小种的种子,适应性较差。为此,提出了一种智能精密播种机优化方案,并使用高精度传感器和控制系统实现多功能播种,控制种子的投放量和调整播种深度,使用节能设备模块化设计和使用易于更换的部件、数据分析功能和简单易用的用户界面。最后,通过田间试验进行功能性试验,结果表明:经过优化后的智能精密播种机播种变异系数≤5%,满足播种农艺要求,可以实现准确的种子投放和深度控制,避免种植密度不均匀和深度不一致等问题,从而提高种植效率和作物品质。

无人机航测方案设计及数据处理研究

近几年,无人机航空摄影测量技术发展迅速,以无人机为平台进行低空摄影测量成为众多测绘人员开展相关工作的一个新选择。以无人机为平台,搭载高分辨率相机,对无人机航测方案进行设计及内业数据处理,生成数字高程模型(DEM)与数字正射影像(DOM)等数字模型,并对比分析了PhotoScan和Pix4D两种软件生成DOM的质量与精度。通过对无人机航测方案的设计及数字模型成果的对比研究,为绘制大比例尺地形图等航测作业提供了参考。

中国女子手球队底线射门技术精准化训练设计及效果研究

本文采用文献资料法、逻辑分析法、秩合比法等研究方法,对比分析第25届女子手球世锦赛前8强队伍和中国女子手球队的底线射门技术运用情况。结果显示:(1)中国女子手球队底线射门RSR值分别为0.500、0.494、0.478、0.344,属C级低水平。(2)针对中国女子手球队底线射门技术短板,聚焦“提高底线射门技术水平”,采用“目标分级原则”对训练目标进行三级分解;训练周期划分为4个阶段,每3周为1个训练阶段,每1周为1个训练单元;训练内容分为个人专项射门训练、阵地配合下底线射门训练、快攻反击下底线射门训练。(3)训练效果:底线射门多变性、对抗下射门能力、创造射门机会方面提高明显;底线射门动作改善、区域配合下射门技术运用、疲劳状态时射门能力、控制失误能力方面提高较大;底线专项射门技术和底线阵地射门技术与集训进度呈明显线性正相关趋势。

“机械精度设计”课程思政教学研究与实践

根据“机械精度设计”课程的教学特点,分别从课程思政探索的思路与目标、设计与实施、特色与创新、反思与分析四个模块出发,探讨课程思政融入的方式方法以及努力的方向。基于知识—能力—人格“三位一体”的人才培养模式,在课程教学中把马克思主义立场观点方法的教育与科学精神的培养结合起来,注重强化学生工程伦理教育,培养学生精益求精的大国工匠精神,激发学生科技报国的家国情怀和使命担当,丰富了铸牢中华民族共同体意识的形式。

建筑智能化方案精准设计方法探索

以智能建筑的顶层设计为基础,在比较不同智能化系统优劣的基础上,提出基于约束条件的智能化设计方案的整体比较方法,为业主智能化设计的投资优化方案提供指导。同时,构建MATLAB模型以简化计算过程,实现设计方案的便捷比较和直观展示,助力精准控制方法在实际应用中的优化。