Effects of wing deformation on aerodynamic performance of a revolving insect wing

Flexible wings of insects and bio-inspired micro air vehicles generally deform remarkably during flapping flight owing to aerodynamic and inertial forces,which is of highly nonlinear fluid-structure interaction（FSI）problems.To elucidate the novel mechanisms associated with flexible wing aerodynamics in the low Reynolds number regime,we have built up a FSI model of a hawkmoth wing undergoing revolving and made an investigation on the effects of flexible wing deformation on aerodynamic performance of the revolving wing model.To take into account the characteristics of flapping wing kinematics we designed a kinematic model for the revolving wing in two-fold：acceleration and steady rotation,which are based on hovering wing kinematics of hawkmoth,Manduca sexta.Our results show that both aerodynamic and inertial forces demonstrate a pronounced increase during acceleration phase,which results in a significant wing deformation.While the aerodynamic force turns to reduce after the wing acceleration terminates due to the burst and detachment of leading-edge vortices（LEVs）,the dynamic wing deformation seem to delay the burst of LEVs and hence to augment the aerodynamic force during and even after the acceleration.During the phase of steady rotation,the flexible wing model generates more ver-tical force at higher angles of attack（40°–60°）but less horizontal force than those of a rigid wing model.This is because the wing twist in spanwise owing to aerodynamic forces results in a reduction in the effective angle of attack at wing tip,which leads to enhancing the aerodynamics performance by increasing the vertical force while reducing the horizontal force.Moreover,our results point out the importance of the fluid-structure interaction in evaluating flexible wing aerodynamics：the wing deformation does play a significant role in enhancing the aerodynamic performances but works differently during acceleration and steady rotation,which is mainly induced by inertial force in acceleration but by aerodynamic forces in steady rotation.

Thermal Effect of a Revolving Gaussian Beam on Activating Heat-Sensitive Nociceptors in Skin

We consider the problem of inducing withdrawal reflex on a test subject by exposing the subject’s skin to an electromagnetic beam. Heat-sensitive nociceptors in the skin are activated wherever the temperature is above the activation temperature. Withdrawal reflex occurs when the activated volume reaches a threshold. Previously we studied static beams with 3 types of power density distribution: Gaussian, super-Gaussian, and flat-top. We found that the flaptop is the best and the Gaussian is the worst in their performance with regard to 1) minimizing the time to withdrawal reflex, 2) minimizing the energy consumption and 3) minimizing the maximum temperature increase. The less-than-desirable performance of Gaussian beams is attributed to the uneven distribution of power density resulting in low energy efficiency: near the beam center the high power density does not contribute proportionally to increasing the activated volume;outside the beam effective radius the low power density fails to activate nociceptors. To overcome the drawbacks of Gaussian beams, in this study, we revolve a Gaussian beam around a fixed point to make the power density more uniformly distributed. We optimize the performance over two parameters: the spot size of static beam and the radius of beam revolution. We find that in comparison with a static Gaussian beam, a revolving Gaussian beam can reduce the energy consumption, and at the same time lower the maximum temperature.

Study on geometric models of non-numerically controlled machining revolving cutter with constant pitch

This paper presents a new approach of designing the revolving cutter with constant pitch, and provides geometric models. The corresponding models in the non-numerically controlled manufacturing, such as designing the helical groove, grinding wheel, relative feeding motion, and calculating the helical angle of the cutting edge, are introduced. The examples are given to testify that the design approach is simple and readily realized in machining the revolving cutter with constant pitch. The effective design and manufacture method provides general references for non-NC machining revolving cutter with constant pitch and reducing the equipments input.

Experimental and Numerical Study on Vibration of the Full-Revolving Propulsion Ship Stern

In order to solve the severe vibration problems of an ocean engineering ship with a full-revolving propulsion system, the navigation tests, including forced vibration response test and modal test, are carded out in its stem. It is concluded from the comparison of the time-domain waveform and spectrum from different measurement points that three main factors lead to a high-level stern vibration. Firstly, the specific dynamic stiffness of a water tank is relatively small compared with its neighbor hold, which makes it act like a vibration isolator preventing vibrational energy transmitting to the main hold. Secondly, there exists high-density local modes in the working frequency range of the main engine and thus the local resonance occurs. Thirdly, the abnormal engagement of gears caused by the large deflection of the shaft bearing due to its low mounting rigidity leads to violent extra impulse excitations at high speeds. Then the modification against the dynamic defects is given by simply improving the specific stiffness of the water tanks. And the effect is validated by the FEM calculation. Some important experience is obtained with the problems being solved, which is useful in the design of ships with the same propulsion system. It is also believed that the dynamic consideration is as important as the static analysis for the ships, and that most of the vibration problems may be avoided with a proper acoustic design.

Study on the Relation between the Drape of Fabrics and Its Revolving Speed

Based on the tests of eight kinds of typical fabrics, the relation between the drape coefficient of different fabrics and its revolving speed was analyzed and discussed. The result of regression curve fitting of experimental data showed that the relation between drape coefficient of fabric and its revolving speed could be expressed by negative exponential equation. Meanwhile, the difference of drape coefficients between static and dynamic at 100 ～ 150r.p.m was suggested to be one of the expressing parameters of the lively degree of fabric dynamic drape.

Nano watermill driven by revolving charge

A novel nanoscale watermill for the unidirectional transport of water molecules through a curved single-walled carbon nanotube（SWNT） is proposed and explored by molecular dynamics simulations. In this nanoscale system, a revolving charge is introduced to drive a water chain confined inside the SWNT, the charge and the tube together serving as a nano waterwheel and nano engine. A resonance-like phenomenon is found, and the revolving frequency of the charge plays a key role in pumping the water chain. The water flux across the SWNT increases with respect to the revolving frequency of the external charge and it reaches its maximum when the frequency is 4 THz. Correspondingly, the number of hydrogen bonds in the water chain inside the SWNT decreases dramatically as the frequency increases from 4 THz to 25 THz. The mechanism behind the resonance phenomenon has been investigated systematically. Our findings are helpful for the design of nanoscale fluidic devices and energy converters.

A Study on Drawing the Shadow of a Curve Revolving Object under Commonly Used Ray

The shadow of a circle casting on a unparallel plane is an ellipse, the shadow algorithm involves a perspective affine transformation. Under commonly used light, the transformation matrix for parallel circles of different diameters casting shadows onto the same plane is identical. Using AutoCAD to get the shadow of a general object of revolution, it only needs to take a series of circles along the axis of symmetry and get their corresponding shadows of ellipses, drawing an envelope to cover all these silhouettes results in the required overall shadow. Then the discrete points of shadow contour line are projected back onto the original object surface, shadow on the object is obtained altogether.

Development of a Side Door Composite Impact Beam for the Automotive Industry

The automobile industry has been searching for vehicles that use less energy and emit fewer pollutants, which has resulted in a high demand for fuel-efficient vehicles. Because of their higher strength-to-weight ratio compared to traditional steel, using fiber-reinforcement composite materials in automobile bodies has emerged as the most effective strategy for improving fuel efficiency while maintaining safety standards. This research paper examined the utilization of fiber-reinforced composite materials in car bodies to meet the increasing consumer demand for fuel-efficient and eco-friendly vehicles. It particularly focused on a carbon-aramid fiber-reinforced composite impact beam for passenger car side door impact protection. Despite the encouraging prospects of the carbon-aramid fiber-reinforced beam, the research uncovered substantial defects in the fabrication process, resulting in diminished load-bearing capacity and energy absorption. As a result, the beam was un-successful in three-point bending tests. This was accomplished by using an I cross-section design with varying thickness because of the higher area moment of inertia. Vacuum-assisted resin transfer molding (VARTM) manufacturing process was used and the finished beam underwent to three-point bending tests.

基于改进YOLOv8的汽车门板紧固件检测算法

针对汽车门板紧固件在复杂场景下存在的检测准确度较低和实时性较差的问题,提出一种小目标改进算法YOLOv8-SOD(small object detection)。在主干网络引入SPD(space-to-depth)模块和自适应权重分配模块,在算法的颈部网络输出位置增加选择性注意力模块,将CIOU损失函数替换为MPDIOU损失函数。实验结果表明,YOLOv8-SOD算法平均检测精度为99.1%,比模板匹配方法和YOLOv8算法分别提高了9.4%、2%,达到了工厂生产流水线的检测标准,具有实用价值。

轨道交通车辆车门系统生命周期环境效益评价

为了推动轨道交通车辆绿色制造的进程,以车门系统为研究对象,建立生命周期模型,构建环境效益评价指标体系,评价车门系统生命周期生产、运输、使用、废弃物处理阶段的主要环境影响,探究电力能源结构替代和焊接工艺变化对车门系统生命周期的环境影响。结果表明:车门系统生命周期不同阶段的环境影响从大到小的排序为生产阶段、废弃物处理阶段、使用阶段和运输阶段;环境影响评价指标从大到小依次为化石能源消耗潜值、温室气体排放潜值和环境酸化潜值;减少生产阶段和废弃物处理阶段的化石能源消耗和温室气体排放有助于产品生命周期环境效益提升;生产阶段中通过减少火电占比,优化电力结构,全球变暖潜值、化石能源消耗潜值和环境酸化潜值可分别降低38.96%、38.90%、38.86%;采用气体金属弧焊工艺替代保护性金属弧焊工艺,全球变暖潜值、化石能源消耗潜值和环境酸化潜值可分别降低64.71%、58.94%、59.85%。

Hot Door CADtools绘制产品立面图和轴测图的分析及实践

矢量软件在绘制产品及工程视图时会出现数据不够准确,参数化控制偏弱等情况,另一方面专业的CAD制图软件又让普通设计师难以下手。基于Adobe Illustrator平台上的Hot Door CADtools插件在这些的问题中找到了平衡点,它能既能够像专业的CAD软件一样为图形标注提供准确的尺寸,同时又让CAD制图变得亲切和富有人性化。

基于Flexsim的定制门窗生产线仿真模型的构建与优化

定制门窗企业正加速推动生产线数字化转型进程以降本增效,然而,瓶颈工序严重影响生产线生产效率。通过使用Flexsim软件对生产线进行建模仿真能低成本反映生产线效能、识别瓶颈工序,为生产线优化提供数据支持,辅助企业决策。以某企业的金属定制门窗机加工生产线为研究对象,应用数字化仿真技术,在Flexsim仿真软件平台建立了机加工生产线及生产工艺数字化模型,并进行仿真测试,针对铝框定制门窗生产的工艺技术特点编写了自定义程序对建模仿真过程进行完善和优化。通过对仿真输出的数据结果与实际生产数据进行详细对比,验证了模型的有效性,并分析了该生产线存在的问题。研究发现:该生产线的端面铣床设备平均利用率低;钻孔铣床打孔工序为瓶颈工序,暂存区堵塞率高;运力不足,待加工工件之间存在竞争运输工具的现象。针对以上问题,根据ECRS(eliminate,combine,rearrange,simplify)原则提出了适合目标企业的改善方案,再次仿真后,瓶颈工序的平均加工时间缩短了15.16%,生产效率提升了4.7%。经实际生产验证了改善方案的有效性,可为定制门窗生产的数字化转型提供有益借鉴。

DOOR-WIN——绘制门窗程序设计

应用Autolisp语言给Acad增加新的指令,设计自动绘制门窗程序,给出在各种情况下安装不同门窗的方法。介绍绘制门窗程序—DOORWIN.LSP设计的详细过程和方法,并详细论述其操作规程和注意事项。

一种基于DOORS的软件需求开发过程优化方法

需求过程是整个软件生存周期中非常重要的一个阶段。因为需求开发过程和需求管理过程的差异,需求开发工具和需求管理工具的选择也可能不同。由此需要将软件需求从需求文档录入至专业需求管理工具的数据库。对此,提出一种基于DOORS的软件需求开发过程优化方法,定义需求文档的编制格式,并开发基于DXL脚本语言的转换插件,最后方便地将RTF格式的需求文档导入至DOORS数据库,能够快速有效地实现需求开发和需求管理之间的衔接。

基于STM32的低功耗智能门锁系统设计

针对传统智能门锁的安全性与高功耗方面存在的问题,设计并开发一款基于STM32F103单片机的智能门锁。本项目可分别通过键入密码、指纹、RFID刷卡三种方式进行解锁,并且对其功耗进行了改良,使其在无人使用的时候达到低功耗。同时,本项目增加了WIFI模式进行连接阿里云从而达到物联网模式,从而监控门锁的实时状态,提高了门锁的安全性与可靠性。本项目的整体设计具有较高的完整性和实用性,不仅使门锁的安全性、便利性得到了提高,还可对门锁的实时状态进行检测,更为智能化。最后,本项目通过实物进行了实验验证,达到了预期结果。

汽车车门外露焊点压痕深度的综合优化

为提升汽车整体焊接质量、改善用户对汽车产品的使用满意度,以某车型车门外露焊点压痕深度调试过程为依据,从人、机、料、法、环5个方面分析车门总成制件外露焊点外观成形不良的产生原因,并总结出以下治理焊点外观不良的有效方法:调整机器人焊接姿态、控制焊钳电极对中度、改善修磨形状和修磨姿态、优化原材料表面油污、修正焊机参数及制定焊接循环水流的流量范围等。试验表明:通过综合治理方案,可以有效提升车门外露焊点外观质量,提高用户满意度,从而提高整车销售量,促进民族品牌快速发展。

2000 MPa级一体式激光拼焊门环关键性能

为提升整车的侧面碰撞和轻量化效果,文章简述一体式激光拼焊和热成型门环关键性能技术,采用三种不同料厚的1000、1500、2000 MPa强度的热成形钢板方案。从焊缝位置拉伸、维氏硬度、极限尖冷弯、低温冲击、延迟开裂五个实验去验证。结果表明,2000 MPa一体式热成型激光拼焊门环为最佳方案。该研究为后续一体式门环设计开发提供了经验。

基于AHP-FCE的门窗执手设计与评价

为合理评价门窗执手中各设计指标对门窗执手性能的影响,根据门窗五金的特点以及现有门窗执手开发中存在的问题,文章采用层次分析法(AHP)和模糊综合评价方法(FCE)构建了门窗执手设计评价模型。首先,运用AHP对相关设计指标归类汇总,从造型、结构、创新三方面建立门窗执手的阶层结构模型。通过Matlab辅助计算,确定了门窗执手基准层中各指标的综合权重。其次,用FCE对各个设计方案建立评价集,并进行合成计算,得到评估结果。最后,通过相互比较,得出了设计方案的优劣排序。在门窗执手设计评价的实例验证中,该评价模型展现出了对评价门窗把手设计方案优劣程度的客观性、准确性,可为门窗执手的开发设计提供量化分析参考。