立式双曲面网板水动力性能优化研究

为研究结构型式及尺寸对立式双曲面网板水动力性能的影响机理,基于计算流体力学方法,建立立式双曲面网板三维数值模型,计算分析其水动力性能,并通过设计制作缩比模型开展动水槽试验,验证数值结果的有效性。开展曲面板弯曲度、弯曲度位置、支撑板间距等不同结构参数对立式双曲面网板水动力性能的影响规律研究,以探究最优化的结构设计方案。研究结果表明:曲面板弯曲度的同步改变和单一改变均会对立式双曲面网板的水动力性能产生不同程度的影响。如果只考虑扩张效果,曲面板A、B的弯曲度均设置为20%左右,或曲面板A弯曲度设置为15%、曲面板B弯曲度设置为25%左右,均可在一定范围内将立式双曲面网板的最大升力系数提高到最大值;但从网板综合性能考虑,后一方案可获得更高的最大升阻比。当曲面板弯曲度位置同步设置为50%时,网板升力系数可达到最大值,此时扩张效果最佳,而当曲面板弯曲度位置同步设置为20%时,最大升阻比达到峰值,网板综合性能相对更好。支撑板间距对立式双曲面网板水动力性能的影响不明显,将支撑板间距设置为420 mm左右,可在小冲角范围内提升其最大升阻比。

基于流固耦合算法的不同材料网板水动力试验

拖网网板的水动力模型试验结果会因加工工艺、加工方式、加工材料和试验条件等多种因素出现不同程度的试验偏差。为探究网板模型不同加工材料对水动力试验的影响机理,选取双开缝矩形曲面网板为研究对象,基于流固耦合算法结合动水槽模型试验,分析丙烯腈-丁二烯-苯乙烯共聚物(ABS)、聚丙烯(PP)、聚氯乙烯(PVC)3种3D打印材料网板模型与传统钢质网板模型的结构响应差异及其对水动力试验的影响规律。结果显示:采用传统金属材料(钢)与非金属材料(ABS)加工的网板模型在结构响应及水动力性能方面均具有显著差异,且随冲角和流速的增加,网板模型的最大变形量增加,进而导致升/阻力系数差异也进一步增加;PVC材料因其弹性模量较大、刚性较强,结构响应与金属材料较为接近,因而对水动力试验结果影响较小。基于上述结果,开展网板水动力模型试验时,可选用PVC作为3D打印材料,但需确保模型制作精度,避免模型材料对水动力试验结果精度的影响。

环境之痛,企业之伤:高管早期环境污染经历对企业盈余管理影响研究

借鉴环境心理学的研究成果,运用高阶理论和烙印理论,本文手工搜集整理了2003—2021年中国沪深A股上市公司CEO环境污染经历独特数据集,研究了CEO的环境污染经历与企业盈余管理行为之间的关系,以及两者关系如何受到董事会的规模、成员任期和平均年龄三种结构特征的影响。研究结果表明,CEO的环境污染经历会塑造CEO一系列的隐性心理特质,导致企业的盈余管理行为的发生,而董事会成员的平均年龄越大,越能抑制有环境污染经历的CEO所在企业的盈余管理行为;董事会规模越大、成员的任期越长,CEO的环境污染经历对企业盈余管理行为的影响会越加剧。研究结论为盈余管理行为研究提供了新的视角,同时,对提高上市公司会计信息质量、完善公司治理机制和促进资本市场健康发展具有一定的启示意义。

Experimental evaluation of mechanical compression of lattice trusses made with Ti6Al4V for aerospace use

Lattice structures are three-dimensional structures composed of repeated geometrical shapes with multiple interconnected nodes,providing high strength-to-weight ratios,customizable properties,and efficient use of materials.A smart use of materials leads to reduced fuel consumption and lower operating costs,making them highly desirable for aircraft manufacturers.Furthermore,the customizable properties of lattice structures allow for tailoring to specific design requirements,leading to improved performance and safety for aircraft.These advantages make lattice structures an important focus for research and development in the aviation industry.This paper presents an experimental evaluation of the mechanical compression properties of lattice trusses made with Ti6Al4V,designed for use in an anti-ice system.The truss structures were manufactured using additive manufacturing techniques and tested under compressive loads to determine mechanical properties.Results showed that lattice trusses exhibited high levels of compressive strength,making them suitable for use in applications where mechanical resistance and durability are critical,such as in anti-ice systems.We also highlight the potential of additive manufacturing techniques for the fabrication of lattice trusses with tailored mechanical properties.The study provides valuable insights into the mechanical behavior of Ti6Al4V lattice trusses and their potential applications in anti-ice systems,as well as other areas where high strength-to-weight ratios are required.The results of this research contribute to the development of lightweight,efficient,and durable anti-ice systems for use in aviation and other industries.

本科护生参与健康评估课程棋盘游戏学习体验的质性研究

目的设计、实施健康评估课程棋盘游戏,并探讨护生的学习体验。方法采用目的抽样法,对12名参与棋盘游戏的护理本科生进行半结构式访谈,运用内容分析法进行资料分析。结果共提炼出2个主题及7个亚主题:学习效果(增强学习动力、巩固所学知识、增强团队协作、领会课程思政),学习反馈(增加游戏难度、改进游戏规则、希望扩大适用范围)。结论棋盘游戏学习效果积极,但需要教师团队优化游戏规则增加趣味性,明确奖励机制激励学生参与,并采用线上线下相结合的方式扩大适用范围。

基于正交试验的登机门框结构刚度设计

大型飞机开口结构的设计是不可避免的,拥有曲率外形的机头大开口变形问题更加突出。本文以某大型飞机机头登机门框为研究对象,采用正交试验方法,得到了影响门框开口变形的主要因素和次要因素以及门框变形随各构件惯性矩变化的规律,为类似大开口结构的刚度设计提供了设计指导。

A Comparative Study on Hydrodynamic Performance of Double Deflector Rectangular Cambered Otter Board

In the present work,the hydrodynamic performance of the double deflector rectangular cambered otter board was studied using wind tunnel experiment,flume tank experiment and numerical simulation.Results showed that the otter board had a good hydrodynamic performance with the maximum lift-to-drag ratio(K_(MAX) = 3.70).The flow separation occurred when the angle of attack(AOA) was at 45?,which revealed that the double deflector structure of the otter board can delay the flow separation.Numerical simulation results showed a good agreement with experiment ones,and could predict the critical AOA,which showed that it can be used to study the hydrodynamic performance of the otter board with the advantage of flow visualization.However,the drag coefficient in flume tank was much higher than that in wind tunnel,which resulted in a lower lift-to-drag ratio.These may be due to different fluid media between flume tank and wind tunnel,which result in the big difference of the vortexes around the otter board.Given the otter boards are operated in water,it was suggested to apply both flume tank experiment and numerical simulation to study the hydrodynamic performance of otter board.

Hydrodynamic characteristics of the double-winged otter board in the deep waters of the Mauritanian Sea

In this paper, we tested the hydrodynamic characteristics of a new, double-winged otter board that consists of a forewing, a leading edge slat and a trailing edge flap. Flume experiments were conducted in a circulating flume tank by using a model with an aspect ratio(AR) of 0.85 and a horizontal planform area( S) of 0.09 m^2. The results indicated that the critical angle( α_(cr)) of the model was 44°, whereas the maximum lift coefficient( C_(Lmax)) was up to 1.715, and the door efficiency( K) was 1.122. The attack angle( α) ranged from 30° to 48° and from 10° to 46° when the lift coefficient( C_L) and door efficiency( K) were greater than 1.2 and 1.0, respectively. To compare the difference between double-winged otter board and traditional Morgere Polyvalent Ovale, same model of Morgere Polyvalent Ovale was also tested under the same experimental conditions. The critical angle( α_(cr)) and maximum of lift coefficient( C_(Lmax)) of the doublewinged otter board were 37.5% and 14.6% larger than those of the Morgere Polyvalent Ovale. Therefore, we concluded that the novel, double-winged otter board was more suitable for bottom trawling fisheries in the deep water of the Mauretania Sea due to its better hydrodynamic characteristics and stability.

3D heterogeneous integration of wideband RF chips using silicon-based adapter board technology

An ultra-wideband mixing component cascaded by a mixing multi-function chip and a frequency multiplier multi-function chip was demonstrated and implemented using 3D heterogeneous integration based on the silicon adapter board technology.Four layers of high-resistance silicon substrate stack packaging are implemented based on the wafer-level gold-gold bonding process.Each layer adopts though silicon via(TSV)technology to realize signal interconnection.A core monolithic integrated microwave chip(MMIC)is embedded in the silicon cavity,and the silicon-based filter is integrated with the high-resistance silicon substrate.The interconnect line,cavity and filter of the silicon-based adapter board are designed with AutoCAD,and HFSS is adopted for 3D electromagnetic field simulation.According to the measured results,the radio frequency(RF)of the mixing multi-function chip is 40-44 GHz and its intermediate frequency(IF)can cover the Ku band with a chip size of 10 mm×11 mm×1 mm.The multiplier multi-function chip operates at 16-20 GHz.The fundamental suppression is greater than 50 dB and the second harmonic suppression is better than 40 dB with a chip size of 8 mm×8 mm×1 mm.The cascaded fully assembled mixing component achieves a spur of better than-50 dBc and a gain of better than 15 dB.

Study on Redevelopment of Kunming West Mountain Forest Park in the View of Experience Economy

At the background of the experience economy becoming major economic form in place of the service economy,forest experience develops vigorously and becomes a new approach for people alleviating pressure,acquiring knowledge,and relaxation. On the basis of analyzing concept and characteristics of the forest experience,this paper analyzed current situation of forest experience by taking Kunming West Mountain Forest Park as an example. It found there are existing problems in subject image,development methods and degree,professional personnel and concept. In view of these problems,it came up with recommendations including determining subject image,designing special products,accelerating cultivation of professional personnel,and strengthening training of forest experience concept. It is expected to provide reference for multi-functional use theory of China and provide ideas for developing forest experience projects.

Study on the Adhesive for the Production of High Strength Four Layer Composite Corrugated Board

In order to study of adhesive which is applicable to the production of high strength four layer composite corrugated board,the composite corrugated medium was respectively coated with cassava starch adhesive,environmental-friendly modified water glass binder,CP-88 starch adhesive,polyvinyl alcohol adhesive and polyvinyl acetate adhesive,then the edgewise crush resistance and flat crush resistance contrast experiment on produced corrugated board samples was tested.The experiment results demonstrated that the produced corrugated board with environmental-friendly modified water glass binder had high edgewise crush resistance,general flat crush resistance and more economic,so the environmental-friendly modified water glass binder can be used for the production of high strength four layer composite corrugated board.

基于提升旅客登机体验的机场摆渡车创新设计研究

为保障航空运输服务的快捷高效,打造更加人性化的远机位登机服务体验。在对旅客远机位登机体验研究基础上,结合用户调研、功能分析、可行性研究等方法,全面剖析旅客在远机位登机过程中对摆渡车的体验诉求,发现各类用户与摆渡车交互出现的新需求点。设计出运用剪叉机构抬升摆渡车车厢与登机口持平的方案。升降式摆渡车极大提高了旅客远机位的登机体验,同时为弱势群体的出行和未来老龄化社会问题提供了更加可靠的解决方案。

基于CFD的拖网网板模型参数对水动力试验的影响研究

拖网网板的水动力模型试验结果经常会因雷诺数、模型尺度等各种试验因素出现不同程度的结果偏差。为研究模型参数对拖网网板水动力试验的影响机理,选取立式V型曲面网板为研究对象,基于水槽模型试验结合计算流体力学数值模拟方法,对比分析其水动力性能及流场分布,探究模型尺度比、板面厚度及模型材料等参数对其水动力试验结果的影响。结果显示:模型尺度比变化对网板升/阻力系数曲线形状无显著影响,但模型尺度缩小过多(20∶1)将导致升力系数在小冲角(α<30°)时偏差明显;模型板面厚度增加会导致升力系数在大冲角(α>30°)下的显著降低,而对阻力系数的影响则主要反映在小冲角(α<30°)时;非金属材料模型由于刚性不足,在水槽模型试验过程中容易因受力后产生一定位移与变形而引起试验结果的偏差。基于上述结果,设计网板水动力模型试验时,应使得模型尺度尽可能大,减小模型尺度对试验结果精度的影响;可适当增加板面厚度以提高模型结构稳定性,增厚范围不宜超过2倍。

柔性电缆PCB内电层载流量研究与实验验证

对某微小型飞行器内部柔性电缆PCB的稳态载流能力和冲击电流载流能力进行了理论计算和设计。通过MIL-STD-275标准和经验公式,对柔性电缆PCB的稳态载流能力进行了复核复算;通过对照GJB4057—2000,估算出柔性电缆PCB的冲击电流载流能力。对于理论计算和估算值,设计了2倍理论值状态下的稳态载流测试和10倍理论值状态下的脉冲电流测试实验,实验结果与预期一致,验证了设计理论计算的正确性。在载流实验中,获取柔性PCB板在各个电流值载流状态下的温度情况,并通过Flotherm软件进行热仿真验证,模拟了PCB在各个电流值状态下的稳定温度,热仿真结果与实际测试结果相吻合,验证了实验数据的真实性与合理性。该载流量实验与仿真数据结果可为后续短时工作微小型飞行器内部PCB设计提供实验数据支撑。

基于用户体验的车载露营箱设计研究

近年来,露营旅游的热度越来越高,很多人喜欢以私家车的方式去露营,而车载露营箱是将私家车改成露营车的关键产品。文章运用文献综述法,挖掘车载露营箱的目标用户需求,结合影响用户体验满意度的因素对车载露营箱进行分析,提出基于用户体验理论的美观性、通用性、功能易用性、安全性、舒适性、情感化的设计原则。通过文章的研究,以期为车载露营箱的设计提供参考与借鉴。

嵌入式综合实验教学平台及教学案例设计

我国高校为培养嵌入式人才开展了大量的理论教学和课程实践。实践能力的培养和提升是嵌入式系统设计人才培养的关键,而嵌入式实验平台是锻炼学生实践能力和创新能力的最佳途径。鉴于目前用于本科教学的嵌入式系统实验平台存在的教学设备相对单一、功能相对简单的问题,以STM32F103为主控芯片,依“核心板为主,扩展外设板为辅”的设计原则,采用模块化设计思想,设计完成了一款嵌入式实验平台,并提供了从基础实验、综合性实验到创新性实验的完整案例,为学生创新思维的提升奠定了良好的基础。

基于高频次问题制作健康教育牌对眼科门诊患者就医体验及门诊护理服务质量的影响

目的:探讨基于高频次问题制作健康教育牌对眼科门诊患者就医体验及门诊护理服务质量的影响。方法:采用便利抽样法于2022年1月1日~5月31日(研究前)和2022年6月1日~10月31日(研究后)在眼科门诊各随机选取50例就诊患者为研究对象,研究前实施常规护理,研究后实施基于高频次问题制作健康教育牌张贴于眼科门诊相关区域;比较研究前后患者就医体验和眼科门诊护士工作满意度,评估研究前后眼科门诊护理服务质量。结果:研究后,眼科门诊患者就医体验各维度评分、眼科门诊护士工作环境和工作强度满意度评分、眼科门诊护理服务质量各维度评分均高于研究前(P<0.01)。结论:基于高频次问题制作健康教育牌应用于眼科门诊,可有效改善患者就医体验,提高眼科门诊护士工作满意度和眼科门诊护理服务质量。

一种纸浆模塑蜂窝板材缓冲性能的研究

目的为了解决因技术水平制约,纸蜂窝材料芯纸构型单一、单层厚度受限等瓶颈问题,开发一种通用型缓冲结构板材。方法以纸浆模塑为原材料,以六棱柱结构为例,设计并加工出一种通过正反插方式组合而成的蜂窝板材,并采用有限元方法进行仿真,得到关键结构参数和相关最优参数组合。结果正反插结构的纸浆模塑板材具有较好的耦合效应,承载能力相较于单层板材大幅提高;结合极限载荷、比吸能等评价指标对板材性能进行定量分析,初始压缩载荷最大可达到73.7 kN,满足托盘等重型包装器具的承载需求。通过极差和方差分析可知,各结构参数对板材承载性能和缓冲性能的影响程度,研究表明单元壁厚、中截面边长对该板材承载性能和缓冲性能影响显著。结论正反插结构解决了现有纸蜂窝材料高度、厚度受限,构型单一等瓶颈问题,提高了纸浆模塑蜂窝板材的承载性能和缓冲性能,可以满足重载要求。与之相关的其他正多边形锥形薄壁管单元亦可以使用同样的正反插设计理念和研究方法。

隧道环向施工缝新型防排水结构性能实验研究

隧道环向施工缝一直是隧道运营过程中出现渗漏水的主要部位,在施工缝局部范围防水板与衬砌之间增设凹凸防排水板,对进入防水板与衬砌之间的围岩渗水进行有效排导,并结合背贴式止水带,形成的隧道环向施工缝新型防排水结构,可有效防止隧道环向施工缝渗漏水或因水压导致的结构破损现象。通过建立室内实验模型,对环向施工缝新型防排水结构的排水性能进行了研究,实验结果表明:新型结构中凹凸排水板内部连通性好,随着注水压力、注水流量的增加,均能有效将水迅速排出,可保证衬砌背后处于无水压或低水压状态;新型结构排水能力强,防水效果好,能够满足普通、富水隧道施工缝渗漏水外排需求。因此,在隧道施工缝处采用新型防排水结构,可大幅改善甚至避免施工缝渗漏水或结构破损问题。

电子纸电磁手写技术研究

电磁手写技术无需内置电池,且具有标配笔的更换成本更优、手写输入效果更好、压感精度更高的优点,相比于电容手写技术,更具有推广性。介绍了电磁手写技术系统、电磁手写技术原理及电磁手写技术优势,分析了电磁手写技术主要技术指标,并从手写延迟优化、贴合校准、磁铁屏蔽、干扰规避等方面提出优化建议,为产品设计者在选择手写技术时提供全面的参考。