科创中国

随着近年来计算机及成像技术的高速发展,视频运动目标检测和跟踪已成为计算机视觉领域的一个研究热点.由于运动目标与摄像头位置的相对变化、室内光照的变化及噪声的存在,以及周围环境中相似物体的干扰,传统的Mean-Shift跟踪算法的跟踪效率、准确性和抗干扰能力均无法满足该应用的需要.为了解决这一问题,在传统Mean-Shift跟踪算法基础之上,提出了颜色直方图更新算法、运动信息融合等改进方案,在Mean-Shift迭代搜索过程中加入了速度矢量加权机制,使目标与相似背景能够有效地被区分开来,提高了系统的抗干扰能力.仿真实验结果表明算法有效提高了跟踪的效率及准确性,能够满足复杂工业环境中运动目标跟踪的需要.

针对传统对数极坐标变换局限于跟踪圆形或类圆形尺度变化目标这一问题,提出一种基于椭圆对数极坐标变换域下目标匹配的尺度变化目标跟踪算法.算法利用Mean Shift进行空间定位,确定目标的形心,通过椭圆对数极坐标变换域中目标和候选的最大相关匹配系数来确定目标的尺度参数.实验结果表明:该文算法在目标小形变和光照变化条件下,跟踪误差较小,尺度跟踪准确率更高,具有较好的鲁棒性.

Straight-line compliant mechanisms are important building blocks to design a linear-motion stage,which is very useful in precision applications.However,only a few configurations of straight-line compliant mechanisms are applicable.To construct more kinds of them,an approach to design large-displacement straight-line flexural mechanisms with rotational flexural joints is proposed,which is based on a viewpoint that the straight-line motion is regarded as a compromise of rigid and compliant parasitic motion of a rotational flexural joint.An analytical design method based on the Taylor series expansion is proposed to quickly obtain an approximate solution.To illustrate and verify the proposed method,two kinds of flexural joints,cross-axis hinge and leaf-type isosceles-trapezoidal flexural(LITF)pivot are used to reconstruct straight-line flexural mechanisms.Their performances are obtained by analytic and FEA method respectively.The comparisons of the results show the accuracy of the approach.Both examples show that the proposed approach can convert a large-deflection flexural joint into approximate straight-line mechanism with a high linearity that is higher than 5 000within 5 mm displacement.This can lead to a new way to design,analyze or optimize straight-line flexure mechanisms.

Multi-way principal component analysis(MPCA)has received considerable attention and been widely used in process monitoring.A traditional MPCA algorithm unfolds multiple batches of historical data into a two-dimensional matrix and cut the matrix along the time axis to form subspaces.However,low efficiency of subspaces and difficult fault isolation are the common disadvantages for the principal component model.This paper presents a new subspace construction method based on kernel density estimation function that can effectively reduce the storage amount of the subspace information.The MPCA model and the knowledge base are built based on the new subspace.Then,fault detection and isolation with the squared prediction error(SPE)statistic and the Hotelling(T2)statistic are also realized in process monitoring.When a fault occurs,fault isolation based on the SPE statistic is achieved by residual contribution analysis of different variables.For fault isolation of subspace based on the T2 statistic,the relationship between the statistic indicator and state variables is constructed,and the constraint conditions are presented to check the validity of fault isolation.Then,to improve the robustness of fault isolation to unexpected disturbances,the statistic method is adopted to set the relation between single subspace and multiple subspaces to increase the corrective rate of fault isolation.Finally fault detection and isolation based on the improved MPCA is used to monitor the automatic shift control system(ASCS)to prove the correctness and effectiveness of the algorithm.The research proposes a new subspace construction method to reduce the required storage capacity and to prove the robustness of the principal component model,and sets the relationship between the state variables and fault detection indicators for fault isolation.

Three dimensional(3D)displacements,which can be translated further into 3D strain,are key parameters for design,manufacturing and quality control.Using different optical setups,phase-shift methods,and algorithms,several different 3D electronic speckle pattern interferometry(ESPI)systems for displacement and strain measurements have been achieved and commercialized.This paper provides a review of the recent developments in ESPI systems for 3D displacement and strain measurement.After an overview of the fundamentals of ESPI theory,temporal phase-shift,and spatial phase-shift techniques,3D deformation measurements by the temporal phase-shift ESPI system,which is suited well for static measurement,and by the spatial phase-shift ESPI system,which is particularly useful for dynamic measurement,are discussed.For each method,the basic theory,a brief derivation and different optical layouts are presented.The state of art application,potential and limitation of the ESPI systems are shown and demonstrated.

利用计算流体力学(CFD)方法建立了一个耦合低温水气变换反应的多孔介质二维拟均相反应器模型.采用FLUENT缺省的单温度模型进行模拟,无法得到气固相两相的温度,而且温度场与实际不符.通过用户自定义标量(UDS)添加固相能量方程,将多孔介质的单温度模型修正为气固相耦合传热两温度模型,以源项的形式添加化学反应,将化学反应热添加到气固相能量方程.湍流模型采用Spalart.Allmaras方程,动力学模型采用Langmuir-Hinshelwood方程,催化剂的性质及操作条件以Wei.HsinChen等的实验为基础.采用有限体积法对模型进行非稳态模拟,对反应器内组分浓度、速度场及温度进行了可视化分析.最后列出了非稳态两温度模型在3个时间点的轴向温度曲线,并且与FLUENT缺省的单温度模型进行了对比,两温度模型的结果与实际更相符.