Robust lane recognition for structured road based on monocular vision

A robust lane detection and tracking system based on monocular vision is presented in this paper.First,the lane detection algorithm can transform raw images into top view images by inverse perspective mapping(IPM),and detect both inner sides of the lane accurately from the top view images.Then the system will turn to lane tracking procedures to extract the lane according to the information of last frame.If it fails to track the lane,lane detection will be triggered again until the true lane is found.In this system,θ-oriented Hough transform is applied to extract candidate lane markers,and a geometrical analysis of the lane candidates is proposed to remove the outliers.Additionally,vanishing point and region of interest(ROI)dynamically planning are used to enhance the accuracy and efficiency.The system was tested under various road conditions,and the result turned out to be robust and reliable.     

气雾射流动态传热实验研究

设计搭建了气雾射流动态传热实验装置,建立了二维非稳态导热反问题模型,研究了表面温度和表面热流密度的时间分布.结果表明在冷却过程中缸体穿越喷射区与淌水区历经了几个不同的换热阶段,温度曲线出现了明显的周期性的特点,成功的模拟了连铸二冷气雾冷却周期性换热的特征.     

具有内模结构的锅炉汽包水位PID控制

锅炉是向诸多工业生产过程提供热能与动力的重要设备之一.为了有效地克服汽包水位的负调现象,采用一种基于三冲量控制方案的内模PID控制方法,即副回路利用常规PI控制算法快速抑制给水流量变化带来的干扰,主回路采用内模PID控制算法用以克服蒸汽流量变化产生的扰动.仿真结果表明所提出的控制策略能够加快响应,减小超调,缩短调节时间,算法简单易于工程实现且具有较强的鲁棒性.     

一种新的无人机偏航航迹计算方法

针对某型无人机模拟操作软件航迹计算精度存在的不足,提出了一种基于椭圆正反解公式的新的航迹计算方法．根据大地坐标系与大地基准相关原理,利用微元分析法计算无人机偏航航迹,通过缩小时间间隔,计算出等高飞行的无人机在小偏航角情形下的航迹经纬度．仿真验证结果表明,该方法能准确地计算小偏航角状态下无人机的飞行航迹,并能正确地对无人机飞越极点和赤道等特殊情况进行航迹修正,可用于其他飞行器的偏航航迹计算．     

Method for calculating dynamic yield stress of fresh cement pastes using a coaxial cylinder system

The calculation of the rheological parameters of fresh cement pastes plays a key role in understanding the rheology of cement-based mixes. Because cement paste is not a simple Bingham fluid, a suitable nonlinear model must be found for characterizing its flow. A test system in which the rotational speed or shear rate can be changed in multiple steps is regarded as a suitable rheological test protocol because the paste reaches a steady state. Furthermore, theoretical derivations show that the solution of the Couette inverse problem corresponding to the modified Bingham model and the Herschel–Bulkley (H-B) model is complex. However, a comparative analysis revealed that the yield stress of fresh paste could easily be obtained through a calculation process based on a Parabolic model. This study presents the complete calculation procedure for this model. The influence of the plug flow is considered, and test points with low minimum shear stress (τ_min) are excluded. Finally, the accuracy of the proposed method is verified through comparisons with the results obtained using mini-cone slump tests. These results show that the dynamic yield stress calculated using the expression of the Couette inverse problem based on the Parabolic model in consideration of the plug flow is very close to the yield stress obtained using the mini-cone slump flow test. This proves that the proposed method could precisely characterize the dynamic yield stress of cement pastes.     

In-plane anisotropy of 1545 aluminum alloy sheet

1　INTRODUCTIONThe in plane anisotropy of mechanical proper ties brings the limitation to the use of alloy sheet.At the same time, during the material processing,the difficulties of contour machining will also be in creased. For this reason, when designing high performance aluminum alloy sheets, the in planeanisotropy is an important performance parameterthat must be considered. Studies have shown thatminor Sc and Zr in the Al Mg Mn alloy can refinegrains of cast ingot, inhib…     

Casting/mold thermal contact heat transfer during solidification of Al-Cu-Si alloy (LM 21) plates in thick and thin molds

Heat flow at the casting/mold interface was assessed and studied during solidification of Al-Cu-Si (LM 21) alloy in preheated cast iron molds of two different thicknesses, coated with graphite and alumina based dressings. The casting and the mold were instrumented with thermocouples connected to a computer controlled temperature data acquisition system. The thermal history at nodal locations in the mold and casting obtained during experimentation was used to estimate the heat flux by solving the one-dimensional inverse heat conduction problem. The cooling rate and solidification time were measured using the computer-aided cooling curve analysis data. The estimated heat flux transients showed a peak due to the formation of a stable solid shell, which has a higher thermal conductivity compared with the liquid metal in contact with the mold wall prior to the occurrence of the peak. The high values of heat flux transients obtained with thin molds were attributed to mold distortion due to thermal stresses. For thin molds, assumption of Newtonian heating yielded reliable interfacial heat transfer coefficients as compared with one-dimensional inverse modeling. The time of occurrence of peak heat flux increased with a decrease in the mold wall thickness and increase in the casting thickness.     

Equivalent heat transfer coefficient at casting/Cu mould interface and temperature field simulation

1　INTRODUCTIONThesolidifiedmicrostructuresofalloysdependontheirsolidifyingprocesswhoseprimarycharacteristicsarethetemperaturedropofthesuperheatedmeltandthere leaseofthelatentheat.Sothestudyontheheattransferduringthesolidificationprocessistheessentialprobleminthesolidificationtheorystudy .Theresearchersworkingonthenumericalsimulationofthesolidificationprocessallknowthattheinterfacialheattransfercoefficientatthecasting/mouldisavariablechangingwithtime .Thusthedeterminationoftheinterfacialh…     

考虑并联机构结构参数误差的控制模型研究

文章以一三平动自由度并联机构为研究对象，有效解决了因理论模型控制实际机构引起的空间层面不对称的问题，进而提高了系统的控制精度。首先建立了坐标系和分析误差源，在此基础上借助空间矢量链分析方法，推导了含误差参数机构控制的正、逆解模型，有效地解决了因立柱导轨垂直度误差引起的机构误差问题。仿真结果验证了模型的正确性，研究成果已应用此类机构的开发中。     

弯曲回弹逆解公式及其在焊管预弯机组设计中的应用

根据小曲率弯曲成形的特点，考虑了板料弯曲的纯弹性变形部分对回弹的影响，推导出根据板料强度、厚度和最终成形半径直接计算弯曲半径的回弹逆解公式，并应用于大口径UOE焊管预弯成形的设计上。根据计算公式给出了B-X100钢级板料UOE焊管预弯成形的预弯辊半径优化设计诺谟图。