基于轻量级OpenPose改进的幻影机手势交互系统

目前人机交互方式多以键盘鼠标为主,而基于深度学习手势识别的交互方式算法准确率不高,且实时性和系统稳定性均有待提升。提出一种新颖的针对轻量级OpenPose进行改进的幻影机手势交互系统。采用轻量级OpenPose将人手简化建模为21个关键点,以MobileNetV1作为基础模型,应用部分亲和域（Part Affinity Fields,PAF）方法实现人手关键点的检测并画出简化骨骼图。为进一步提升人机交互系统的实时性,采用幻影模块（Ghost Module）对卷积层进行降维,用更少的硬件资源取得同样的识别效果。最后搭建验证环境,根据画出的人手骨骼图进行模式匹配,根据匹配识别结果生成交互控制指令,经由蓝牙通讯将指令传送至Arduino UNO平台控制小车实现交互响应。经过初步训练后,该系统在COCO2017验证集上能实现58.7%的准确率,保持了原始OpenPose网络和轻量OpenPose网络的人手关键点识别效果,在家用PC机上可实现每秒32~36帧的识别速率和较高的手势识别率。     

应用一步流动法快速测定土水特征曲线试验研究

实验室常用压力板仪进行常规试验测定粉土土水特征曲线（SWCC）,需耗费数月时间,效率不高。对快速测定粉土SWCC进行了试验研究：采用压力板仪对粉土试样开展一步流动法试验;同时,用Hydrus-1D建立一维水分运移模型;结合模型对干密度为1.78 g/cm3粉土试样中溢出水量随加压时间的关系曲线进行拟合,并得出VG模型中难以实测的参数α和n;根据参数反算出粉土试样SWCC并和压力板仪常规试验的SWCC进行对比。为了消除试验中加载压力过大可能造成的固结对试验结果的影响,还对干密度为1.65 g/cm3的粉土试样进行固结试验使其干密度增大为1.78 g/cm3,再对固结后粉土试样分别进行常规试验和一步流动法试验。对由两种试验得到的固结粉土的SWCC与初始干密度1.78 g/cm3粉土由两种试验实测的SWCC进行了比较。结果表明：① 一步流动法试验拟合的SWCC与常规试验实测的SWCC重合度高;② 一步流动法试验具有快速性和有效性;③ 由Hydrus-1D建立的一维水分运移模型得出的SWCC与常规试验实测的SWCC接近;④ 一步流动法试验结果不会受到固结的影响。     

大跨度楼盖结构在运动荷载下的振动性能

为研究人员运动荷载下大跨度楼盖的振动特性,以内蒙古伊旗全民健身体育中心大跨度张弦梁楼盖体系为背景,采用生物力学测力平台进行人员行走、跑步、跳跃、起立等运动荷载实测和相关分析研究.考虑可能出现的各种运动荷载工况,对大跨度张弦梁楼盖区振动开展有限元分析和现场实测.分析表明:行走、跑步及跳跃荷载工况下,人员动力放大系数分别约为1.2、2.4及4.9,大跨度楼盖在人员运动荷载数值模型激励下,所得有限元分析结果与现场实测竖向加速度峰值及理论计算值吻合较好.     

内聚力模型在裂纹萌生及扩展中的应用

断裂及开裂是工程中严重的结构失效形式.结合传统断裂力学中应力强度因子K以及J积分,综述了内聚力模型基本思想及发展,分析了典型的内聚力模型及模型应用的局限性,总结了不同内聚力模型在有限元中的实现形式,概述了国内外学者关于内聚力模型解决不同材料裂纹萌生与扩展的研究状况,得出了内聚力模型可以用以研究裂纹尖端塑性变形、静力和疲劳载荷条件下的蠕变开裂,以及金属、岩土材料及混凝土、复合材料及纳米晶材料裂纹萌生与裂纹扩展的结论.     

饱水对岩溶灰岩力学性质与纵波波速的影响

为研究饱水对岩溶灰岩力学性质和纵波波速的影响,进行自然和饱水状态下岩样的力学性能和弹性波测试。试验结果表明:饱水对岩溶灰岩的单轴抗拉强度、抗拉强度和弹性模量有明显的软化作用,饱水状态试样的峰值应变和泊松比整体上大于自然状态的对应值;岩溶灰岩试样在饱水条件下的纵波波速均明显高于自然状态下的纵波波速,试样的单轴抗压强度和抗拉强度与纵波波速具有较高的线性相关性。基于目前的研究现状,阐述了研究成果在隧道与周边高压充填隐伏溶腔间防突岩层稳定性评价及最小防突厚度确定中的应用。     

Bioelectrochemical sulfate reduction enhanced nitrogen removal from industrial wastewater containing ammonia and sulfate

Low organic carbon-to-nitrogen ratio and existing sulfate (SO₄²⁻) in industrial wastewater limited nitrogen removal. Coupling SO₄²⁻ reduction with sulfide autotrophic denitrification provides a novel strategy. Herein, bioelectrochemical sulfate reduction was coupled with heterotrophic sulfate reduction to drive sulfide autotrophic denitrification. In this coupled system, total nitrogen (TN) removal efficiency was increased from ~25% to ~85% by inputting −45 mA electricity. With the help of supplying electrons to denitrification through SO₄²⁻ reduction, coulomb efficiency was improved to 61.5%. Also, bioelectrochemical sulfate reduction could improve sulfur recovery and thus increase TN removal efficiency. Furthermore, through tuning turnover numbers of SO₄²⁻, high TN removal efficiency can be obtained at various concentrations of SO₄²⁻. Moreover, main functional bacteria in this system were identified. Finally, ~75% TN removal efficiency was achieved with real wastewater in this system. Overall, this work offered a new approach for efficient nitrogen removal from industrial wastewater containing SO₄²⁻.     

Electrically conductive and thermally stable SiC-TiC containing nanocomposites via flash pyrolysis

Flash pyrolysis, which combines conventional pyrolysis with flash sintering, was first conducted to produce polymer derived SiC-TiC nanocomposites. Pre-pyrolysis at 800℃ allows the conversion from titanium isopropoxide (TTIP) modified polysiloxane to an amorphous SiTiOC ceramic. The subsequent application of an electric field gives rise to the formation of turbostratic carbon and creates Joule heating to obtain a sample internal temperature of ~1400℃. The precipitation of β-SiC, TiC, as well as titanium oxides is realized upon carbothermal reduction of extensively phase separated SiO₂ and TiO₂ with carbon. Increasing TTIP content embodies the nanocomposites with prominent electrical percolation behaviors. The electrical transport of the synthesized ceramics follows an amorphous semiconductor mechanism. High thermal stability in air is guaranteed, thanks to the in-situ formed TiC nanocrystals and preferentially reduced amorphous carbon. Flash pyrolyzed nanocomposite with a Ti:Si molar ratio of 0.20 exhibits the highest electrical conductivity (0.696 S/cm) and minimum mass change (~2%) at 1000℃, serving as a competitive candidate for electro-discharge machining (EDM) applications or self-standing conducting devices that must withstand high temperature conditions.     

Electrochemical investigation of La0.4Sr0.6TiO3 synthesized in air for SOFC application

Journal of Applied Electrochemistry - La-doped titanate materials have been widely investigated as alternative Ni-free anodes for solid oxide fuel cells (SOFCs). In this study, La0.4Sr0.6TiO3 (LST)...     

移动硬盘盒精密热流道注塑模具设计

热流道注塑模具在模具行业中的应用越来越广泛,采用热流道系统不仅可以保证塑件质量、提高材料的利用率,还能显著提高塑件的生产效率。通过对移动硬盘塑料件的结构及成型工艺特点进行分析,设计了移动硬盘塑料件热流道注射模具,重点对热流道模具热平衡计算和热流道浇注系统进行了分析计算,模具采用单点热流道、一模两件潜伏式浇口、外滑块抽芯机构及斜推杆抽芯成型倒扣设计。实践证明,该移动硬盘塑料件模具设计结构合理,在提高塑料件成型质量的同时,提高了材料的利用率及生产效率,为同类结构特点的热流道注塑模设计提供了参考。     

Ba—P复合变质对铝硅合金初晶硅的细化作用

研究了钡、磷及钡磷复台变质对过共晶铝硅合金初晶硅的细化作用，发现钡变质可细化初晶硅的尺寸，同时使硅晶体由板块状改变为树枝状；磷变质可明显细化初晶硅，但对其形状因子改变不大；但磷复合变质综合了二者的优势。硅晶体表面有钡或钡的化合物的吸附，认为吸附抑制机制是钡变质的实质。