基于无人机和深度学习的大型垃圾填埋场覆膜病害智能识别方法研究

为提高大型生活垃圾卫生填埋场的堆体覆膜穿刺、撕裂等常见病害的巡检效率,以广州市兴丰生活垃圾卫生填埋场为研究对象,基于无人机航拍和深度学习模型,考察了无人机的选型和巡航参数,使用无人机采集病害样本并在病害图像识别模型中采用过采样的训练策略。并在YOLOv5模型上增加细微目标识别层,可实现较高的识别准确率与召回率。研究结果表明:在病害图库样本数量相对有限的前提下利用过采样的策略提升了样本的代表性与均衡性,显著提高了模型病害识别的准确率。无人机结合高精度RTK定位技术能准确定位航拍照片坐标,解决了无明显参照物下覆膜病害定位困难的问题。通过查询病害缺陷照片的地理信息,可以快速找到病害位置,有助于及时开展修复作业。

焊后时效对异种铝合金搅拌摩擦焊接头的影响

采用光学显微镜(OM)、扫描电子显微镜(SEM)、万能力学试验机、显微硬度仪等表征分析了焊后时效工艺对A356-T6/6061-T6异种铝合金搅拌摩擦焊接头的影响,并讨论其影响机制。结果表明,人工时效有利于提高接头的抗拉强度和屈服强度,但延伸率有所下降。当时效温度为165℃、时效时间5 h时,接头抗拉强度和屈服强度分别达285、240 MPa,约为A356-T6母材的96.6%和90%,比未人工时效接头强度提高35.7%和60%,延伸率下降40%。焊后人工时效对整个接头的硬度都有一定的提高作用,焊缝各区提高幅度不一致,改变了焊缝区的硬度分布格局,导致低硬度区和断口位置由返回侧热影响区向前进侧转移。人工时效能有效降低第二相的面积分数和颗粒尺寸,提高第二相的圆整度。但保温温度过高和时间过长,均可能导致第二相面积分数的提高和粗化。

航空高职院校制造类专业课程体系构建的实践与探讨

本文围绕航空制造类专业基于"生产型"课程体系思路与开发流程。以"生产型"工作流程人才培养模式为主线,以能力为本位,从职业岗位需求出发的课程体系构建思路,给出了基于生产型的航空制造类专业课程设置框架。

Land Use/Cover Changes and Environmental Consequences in Songnen Plain,Northeast China

The Songnen Plain in Northeast China,one of the key national bases of agricultural production,went through remarkable land use/cover changes in recent years.This study aimed to explore the long-term land use/cover changes and the effects of these changes on the environment.The Landsat-based analysis showed that,during 1986-2000,cropland,built-up land and barren land had increased,among which cropland had the largest increase of 9,198km2 with an increase rate of 7.5%.Woodland,grassland,water body and swampland had decreased correspondingly,among which grassland had the most dramatic decrease of 6,127km2 with a decrease rate of 25.6%.The transition matrix results revealed that grassland,woodland and swampland were the three main land use types converted to cropland.Climate warming created the potential environment for the conversion of grassland and swampland into cropland.Land resources policy made by central and provincial governments of China affected the pattern and intensity of land use.Land use/cover changes accompanied by climatic variation brought out a series of environmental consequences,such as sand desertification of land,land salinization and alkalinization,grassland degradation,and more frequent floods.Under this circumstance,optimized land use structure and restoration measures are needed.

Numerical Analysis of Nozzle Clearance's Effect on Turbine Performance

Variable nozzle turbine （VNT） has become a popular variable geometry turbine （VGT） technology for the diesel engine application. Nozzle clearance, which can＇t be avoided on the hub and shroud side of the VNT turbine due to the pivoting stators, can lead to turbine performance deterioration. However, its mechanism is still not clear. In this paper, numerical investigation, which is validated by experiment, is carried out to study the mechanism of the nozzle clearance＇s effect on the turbine performance. Firstly, performance of the mixed flow turbine with fixed nozzle clearances tested on flow bench. Performance of the tested turbine with the same nozzle clearance is numerically simulated. The numerical result agrees well with the test data, which proves correct of the numerical method. Then the turbine performance with different nozzle clearances is numerically analyzed. The research showed that with nozzle clearance, flow loss in the nozzle increases at first and it reaches the maximum value when the clearance ratio is 5%. Flow at the exit of the nozzle becomes less uniform with nozzle clearance. The negative incidence angle of the rotor also increases with nozzle clearance and leads to more incidence angle loss in the rotor. The low energy fluid formed in the nozzle due to the nozzle clearance migrates from hub to shroud side in the rotor, which is another main reason for the rotor＇s performance degradation. The present research exposed the mechanism of the dramatically decrease of the turbine performance with nozzle clearance： （a） The loss associated with the nozzle leakage increases with the nozzle clearance; （b） The flow loss grows up quickly in the rotor due to the incidence angle loss and migration of the low energy fluid from hub to shroud side.

Analysis of geological conditions and thermal reservoir characteristics of Guantao Formation in new coastal region

Geothermal resources is one of the most practical and competitive new energy at present,and there is abundant geothermal resources in the new coastal region.The article get the three following conclusion through the geothermal geological condition by the drilling strata and the condition of the reducing test:stratigraphic division is done by the analysis of formation lithology and the drilling aging;the water yield is higher than 100m3/h,the flow temperature is 67℃--71℃;the average geothermal gradient of the overlying strata is 3.08℃--3.33℃/100 m.

Remote Detection of Varying Water Storage in Relation to Surfacial Temperature of Aral Sea

Lake monitoring by remote sensing is of significant importance to understanding the lake and ambient ecological and environmental processes. In particular, whether lake water storage variation could predict lake surfacial temperature or vice versa has long fascinated the research community, in that it would greatly benefit the monitoring missions and scientific interpretation of the lake change processes. This study attempted to remotely detect the dynamics of the Aral Sea and pursue the relationships between varying lake water storage attributes and surface water temperature by using MODIS LST(Moderate-resolution Imaging Spectroradiometer Land Surface Temperature) 8-day composite products, satellite altimeter data, and actual meteorological measurements. Their associations with lake Surface Water Temperatures(SWT) were then analyzed. Results showed the lake water surface areas and elevations of the North Aral Sea tended to increasing trend from 2001(2793.0 km^2, 13.6 m) to 2015(6997.8 km^2, 15.9 m), while those of the South Aral Sea showed a decreasing trend during 2001(20 434.6 km^2, 3.9 m) and 2015(3256.1 km^2, 0.9 m). In addition, the annual daytime and nighttime lake SWT both decreased in the North Aral Sea, while only the daytime SWT in the South Aral Sea exhibited an increase, indicating a rising deviation of diurnal temperatures in the South Aral Sea during the past 15 yr. Moreover, a lower correlation was found between variations in the daytime SWT and storage capacity in the South Aral Sea(R^2 = 0.33;P < 0.05), no fair correlations were tested between lake water storage and daytime SWT in the North Aral Sea nor between lake water storage and nighttime SWT in either part of the sea. These results implied that climate change, if any at least during the research period, has no significant effects on lake dynamics over the two sectors of the Aral Sea with anthropogenic disturbances. However, climate change and human activities may overlap to explain complex consequences in the lake storage variations. Our results may provide a reference for monitoring the spatiotemporal variations of lakes, increasing understanding of the lake water storage changes in relation to the lake SWT, which may benefit the ecological management of the Aral Sea region, in the effort to face the likely threats from climate change and human activities to the region.

Research and Measures on the Security of Internet of Things

With the development of intelligent perception, recognition technology and pervasive computing,Internet of things（IoT） is widely used, the security problem is also concerned by more and more researchers.IoT is a double-edged sword. On the one hand, it has great potential in simplifying the business process and provides an effective way for the enterprise to interact with the customers. But on the other hand, it also provides convenience for cyber crimes and hackers. First of all, Three layers logic architecture of IoT is introduced, andthe security problems at each level and the key points of the research are expounded, and then the security requirements are analyzed. The main causes of security problems are summarized and analyzed： physical attack and the threat of equipment and malware, file attack and hacker attack. Finally, through the application of the existing technology in IoT environment, the exploration of new technology and the security of the hardware related to IoT, the security of the software and the security team, the future research direction of the security of IoT is pointed out.

漫谈粉彩瓷的传承与形式意蕴

粉彩瓷具有粉润优雅的颜色,加上层次丰富的色调,映衬在白如玉的瓷器上,形成了粉彩独有的艺术风格。年轻人应通过各种渠道了解这门艺术,了解粉彩瓷的艺术魅力。

王军

由于L-半胱氨酸（Cysteine，Cys）在病理生理学以及临床医学等学科领域的重要性，Cys的高选择性检测长期以来受到高度关注．重点综述2010年至今可视化检测Cys的传感器／体系，并根据传感机制的不同分为反应型单分子传感器以及基于金属配合物和纳米材料的传感体系．还简单展望了Cys传感器／体系的发展趋势．

Numerical Investigation of the Superimposed Effects on Stator Wake Oscillation in an Axial-radial Combined Compressor

The superimposed influences of the blade rows in a multistage compressor are important because different matches of upstream and downstream blades can result in significant differences in the stator wake oscillation. Numerical investigation of the axial stator wake oscillation, which is affected upstream by the axial rotor and downstream by the radial rotor, was performed in an axial-radial combined compressor. Many configurations with different blade numbers and locations, which influence axial stator wake oscillation were investigated. When rotors have equal blade numbers, the axial stator wake oscillates periodically versus time within time T(moving blade passing 1/3 revolution). In contrast, stator wake oscillates irregularly within T when rotors have different blade numbers. A model-split subtraction method is presented in order to separate the influences of the individual blade rows on the wake oscillation of the axial stator. Analysis from the rotor-stator configuration showed that the unsteady flow angle fluctuation response is caused by the upstream rotor. For the rotor-stator-rotor configuration, the unsteady flow angle fluctuations are influenced by upand downstream blade rows. With the model-split subtraction method, the upand downstream influences on the flow angle fluctuation could be clearly separated and quantified. Low amplitudes could be observed when the influences from upand downstream moving rows were superimposed with the "positive peaknegative peak" type wave. Clocking investigations were carried out to change the relative superimposed phase of influences from the surrounding blade rows in order to modulate the amplitudes of the axial stator wake oscillation. However, the amplitudes did not reach the maximum when they were superimposed with "positive peak-positive peak" type wave due to the impact of the interaction between the two moving blade rows.

基于LiDAR点云的大型垃圾填埋场数字高程模型建模方法研究

为解决无人机巡检应用于生活垃圾填埋场堆体稳定性监测的技术难点,以国内华南地区最大的兴丰垃圾填埋场为研究对象,对其进行点云数据采集,采用径向基函数、最近邻域、不规则三角网、反距离加权方法4种方法建立数字高程模型,并通过对堆体阴影图、地形相关性、等高线图、最大排水长度图的模型参数分析,比选适宜于垃圾填埋场的点云采集与建模方法。结果表明:垃圾填埋场表面覆盖有反射方向性强的树脂类覆膜,对激光雷达射线的反射有明显的方向性,对无人机的可测试范围有较强的抑制作用。50 m航线高度下,需要航线间隔≤60 m才可保障高于100点/m^(2)的数据采集量。在覆膜坡度较大区域,需布置单独的航线。比对建模及应用效果可知:不规则三角网方法综合性能最佳,地形高程精度偏差≤2 cm,可以较好地应对地形等高线绘制、流水流迹模拟等任务。