微涡流发生器对激波边界层作用诱导的流体分离控制

基于大涡模拟(Large Eddy Simulation)方法,结合高阶TCD/WENO混合格式,对2.5Ma超声速激波/边界层干扰诱导的微楔和微叶片两种微涡流发生器控制进行了数值模拟。数值结果表明:从边界层厚度与分离区大小及结构变化均说明两种涡流发生器对激波边界层分离起到明显抑制作用。对于微楔式涡流发生器,入射激波对微楔尾涡压缩作用明显,使流向涡对的卷吸加强,从而增加边界层内外流体能量交换。微叶片式涡流发生器的控制机理与微楔相似,但其涡对在尾部较远处易破裂,会影响内外流体之间的能量交换。     

学龄前视障儿童触觉训练玩教具设计研究

目的 在倡导融合教育和全纳教育的社会背景下,从人文关怀和伦理价值的视角探索学龄前视障儿童平等地享受教育资源和玩享权利的玩教具产品实现形式,以期改善玩教具配套的现实困境.方法 通过分析学前视障儿童触觉训练教育干预概况、梳理学前视障儿童感知特征、剖析触觉训练玩教具现状及问题,以教育补偿中的触觉训练为根本,提炼出系统易用、玩教一体、包容平等的设计原则,并分别以模块化设计、情趣化设计和包容性设计为设计方法展开构思和创意,从系统、宏观的角度围绕学前视障儿童的触觉能力、认知能力、学习能力等要素展开系列化玩教具设计实践.结论 为学前视障儿童的早期干预和教育补偿提供产品保障,使之充分感受到世界的温暖和人性的关爱.     

饱和黏弹性土中圆柱形隧洞的振动特性

基于流体不可压缩饱和多孔介质理论,将衬砌视为具有分数导数本构关系的多孔黏弹性体,在频率域内研究了在内水压力作用下饱和黏弹性土和衬砌系统的振动特性。通过引入与孔隙流体体积分数有关的应力系数,合理地确定了隧洞边界衬砌和孔隙水共同承担的内水压力值。利用衬砌内边界上的边界条件以及衬砌和土体界面处应力和位移的连续性条件,给出了隧洞边界部分透水条件下饱和黏弹性土和分数导数型黏弹性衬砌系统简谐耦合振动时系统动力响应的解析解。结果表明:饱和黏弹土和衬砌结构的动力响应与衬砌材料的黏性有关;应力系数合理地确定了衬砌和孔隙水共同承担的内水压力值。     

多功能氟碳防腐涂层的制备及其性能

本文以醇溶性无机富锌为底漆,环氧云铁为中间漆,同时,面漆以FEVE型氟碳树脂为基料,配合多种防锈颜填料,并以陶瓷空心微珠为隔热填料,在钢材表面制备集防腐隔热于一体的多功能涂层。研究了多功能氟碳涂层的力学性能、耐候性能、隔热性能、电化学性能以及微观结构。结果表明:制备的多功能氟碳涂层硬度达3H以上、耐盐雾达5000h,耐人工紫外老化5000h以上;同时,当陶瓷空心微珠的掺入量为10%时,氟碳涂层的隔热效果达到最佳。     

钢悬链式立管与海床相互作用模拟方法研究

基于大挠度曲线梁模型和弹性地基梁理论,研究了钢悬链式立管与海底相互作用的模拟方法。采用大挠度曲线梁模拟钢悬链式立管的悬垂段,采用弹性地基梁模拟海底流线段。钢悬链式立管与海底相互作用模型不仅考虑了弹性支撑反力和摩擦力,还考虑了动态效应的阻尼力和液化土的吸力。分析表明,采用大挠度曲线梁和弹性地基梁模型分析钢悬链式立管,其单元尺寸的影响较小,可采用较大的计算单元,从而缩短计算时间、减少内存。基于该方法的开发程序与商用程序OrcaFlex吻合较好,但对单元长度的敏感性远远小于OrcaFlex。     

Image Processing of Manganese Nodules Based on Background Gray Value Calculation

To troubleshoot two problems arising from the segmentation of manganese nodule images-uneven illumination and morphological defects caused by white sand coverage, we propose, with reference to features of manganese nodules, a method called“background gray value calculation”. As the result of the image procession with the aidthis method, the two problems above are solved eventually, together with acquisition of a segmentable image of manganese nodules. As a result, its comparison with other segmentation methods justifies its feasibility and stability. Judging from simulation results,it is indicated that this method is applicable to repair the target shape in the image, and segment the manganese nodule image in a short time. Also, it could be used tosynchronously process a large number of manganese nodules on different conditions in an image, laying a good foundation for automatic underwater manganese nodule survey. Even if the target in the image is slightly distorted, the statistical data of manganese nodules are still accurate. Moreover, other methods cannot be fully applied to the segmentation of manganese nodule images; in another word, the effectiveness and stability of this method are proved.     

建筑围护结构能耗的计算机仿真设计

通过对比国内外主要建筑能耗模拟软件,阐述建筑节能潜能主要方法、途径以及建立围护结构温度、能耗模型,并分析建筑围护结构模拟软件的设计和实现计算机仿真的意义。     

Multi-cylinder electrohydraulic digital loading technology for reproduction of large load

To solve the problem of the control accuracy in electrohydraulic loading systems caused by load increment, this paper proposes a multi-cylinder electrohydraulic digital loading (MEDL) technology for accurate reproduction of large load. A traditionally used single cylinder loading (SCL) is replaced by a new hydraulic cylinders group that includes N hydraulic cylinders at each point, in which one is controlled by the electrohydraulic servo valve and the others (N-1) are controlled by the on-off valve. The areas of the on-off valve controlled (OVC) cylinders form an increasing geometric sequence with a common ratio of 2. In addition, the force of the servo valve controlled (SVC) cylinder can be regulated continuously, and the OVC cylinders have only two states of no force or maximum force. There should be no force tracking error caused by nonlinear factors for the OVC cylinders. Thus, a continuous accurate large loading can be achieved by changing the working area of the cylinders group. Moreover, an improved full closed-loop (FCL) control strategy is proposed to solve the load reverse sudden change caused by the asynchronous opening and closing of the servo valve and on-off valve. With a case of N = 4 for MEDL, AMESim simulation results illustrated that the tracking error of the 4-cylinder group was about 1/6 of the single cylinder under a case of 40 kN. Furthermore, extensive experiments conducted on a real full loading bench under the FCL control method indicated that compared with SCL, the tracking error of the 4-cylinder group with a multi-step signal and various-frequency sinusoidal signals were reduced by 73% and 46%, respectively. Both simulation and experimental results proved that the proposed MEDL technology improved the loading accuracy and optimized the dynamic performance of the system.     

基于LCTF成像仪的光谱反射率测量研究

目标物体的光谱反射率是水下光谱检测中重要的物理特性。复杂的水下环境,尤其是浑浊水体对光有较强的吸收与散射作用,增大了光谱探测的难度。文中在比对测量法的基础上,提出了引入黑、白板对测量结果进行矫正的光谱反射率探测方法。利用基于液晶可调谐滤光片的水下光谱成像仪快速稳定地采集多浊度、多光照条件下的光谱图像数据。数据分析结果证明了浊度增加会使得黑、白板的像素响应比值非线性增加,尤其在400~500 nm范围内。且基于黑白板的光谱反射率探测方法可以有效去除水体散射对光谱反射率重建的影响,使得不同浊度条件下得到的目标物光谱反射率最大绝对误差为5.3%。