大螺距连续螺旋折流板换热器制造工艺研究

针对大螺距连续螺旋折流板螺旋升角大、成型困难的问题，分析了连续螺旋板成型的基本原理，提出了螺旋导向+热成型+周向力的成型方案，设计制造了连续螺旋折流板压制成型模具，压制过程中通过模具转动得到了一个完整周期的连续螺旋折流板；分析了大螺距连续螺旋折流板钻孔加工的难点，提出了采用数控加工中心铣削加工的方案。通过合理的刀具选择和装夹设计加工出了连续螺旋折流板，解决了大螺距螺旋面管孔加工问题，为大螺距连续螺旋折流板的成型及加工提供了借鉴。     

炮掘岩巷大块矸石成因分析及防治措施

为了解决辛置煤矿东四延伸皮带巷掘进过程中由于大矸产生率过高造成巷道掘进效率低下的问题,在对大矸产生原因进行分析的基础上,提出采用锲直复合掏槽爆破方式代替原有的直眼掏槽爆破,并从巷道掘进效率、大矸产生率等方面进行详细对比分析。掘进采用锲直复合掏槽爆破方式后,大矸产生率从30%以上降低到20%以内,且最大矸石粒径从1000 mm×800 mm降低到500 mm×400 mm,巷道掘进进尺从1.5 m/d提升至3 m/d,应用效果显著。     

大倾角综放开采放煤工艺参数模拟分析

利用离散元软件PFC2D,对平舒矿沿倾向上开采时的大倾角放顶煤的冒落规律进行研究,得出不同参数下放煤过程的煤矸冒落图形。通过对不同采煤高度、放煤步距的采出率和含矸率的对比分析,得出上向放顶煤开采的最合理放煤工艺参数,为后续大倾角放顶煤不同开采方向的工艺参数优化提供了依据。     

Perceptual quality assessment for multimodal medical image fusion

Recent years have witnessed that the multimodal medical image fusion (MMIF) plays critical roles in clinical diagnostics and treatment. Many MMIF algorithms have been proposed to improve the MMIF images quality. The quality of multimodal medical fused images will significantly affect the results of the clinical diagnosis. However, little work has been designed to evaluate the effectiveness of MMIF algorithms and the quality of MMIF images. To this end, this paper presents a perceptual quality assessment method for MMIF. A MMIF image database (MMIFID) is first built to employ the classical MMIF algorithms, and the subjective experiment is conducted to assess the quality of each fused image. Then, a no-reference objective method is proposed for the perceptual quality evaluation of MMIF images,which uses Pulse Coupled Neural Network (PCNN) in Non-subsampled Contourlet Transform (NSCT). A fused image is decomposed by NSCT into low frequency sub-band (LFS) and high frequency sub-band (HFS). It is used to motivate the PCNN processing, and large firing times are employed to measure LFS and HFS. Finally, two components evaluation results are combined to obtain the overall objective quality score. Experimental results based on the MMIFID indicate that our presented method outperforms the existing image fusion quality evaluation metrics, and it provides a satisfactory correlation with subjective scores, which shows effectiveness in the quality assessment of medical fused images.     

基于网络数据统计的食品欺诈研究分析

目的 建立符合我国国情的食品欺诈数据库, 补充国际上已建立的经济利益驱动型掺假(economically motivated adulteration, EMA)数据库空白。方法 搜集2001~2019年发生的食品欺诈行为, 初步建立具有中国国情的食品欺诈数据库。对数据库中信息完备的454条欺诈数据进行分析。结果 媒体报道数据占食品欺诈信息总数的71.6%; 食用农产品、酒类、乳制品、肉制品等11类产品是欺诈事件发生较多的食品类别; 产品欺诈(72.2%)高居食品欺诈类型的首位; 2001~2019年食品欺诈事件数量呈现出先上升后降低, 再上升再降低的“M”状趋势; 目前食品欺诈检测技术主要以理化分析技术为主, 针对的食品类别还有限; 食品欺诈信息以中国为主(89.0%), 涉及到世界各个地区。结论 食品欺诈是广泛存在的全球性问题, 本研究建立的食品欺诈数据库为预防食品安全风险起到了重要的技术支撑作用。     

空间红外大口径折射式低温镜头设计与验证

针对目标探测类空间红外相机大范围成像、高灵敏度探测、高精度定位等应用需求,文中提出采用像方远心光路和低温光学技术结合的解决方案,设计了物方视场角8°×8°、入瞳口径265 mm、工作温度200 K的像方远心折射式光学系统。镜头最大口径280 mm,采用多级分散的弹性支撑设计,解决大口径低温透镜装框、透镜组件支撑和镜头整体安装各环节的热应力卸载问题。在保证高刚度和低漏热的情况下,使低温下透镜的热应力对镜头能量集中度的影响降低到可接受范围内。镜头完成装调及室温下像质确认后,进行了力学振动试验,并将其制冷到200 K水平测试像质,测试结果表明,镜头能量集中度达到轴上75%,边缘视场72%。     

A star pattern recognition algorithm for cameras with large FOV

In most large field of view (FOV) observations, the distortion problem is inevitably and significantly more serious than in small FOV ones. In the circumstances, many traditional star identification approaches are not able to efficiently identify stars any more. In order to deal with this problem, we put forward a star identification method that is less sensitive to distortion. The method first processes stars in the central area of the image, using traditional identification logic, and then applies the region growing strategy to enlarge the identified regions iteratively until the entire image is covered. The performance of the new scheme is analysed in the presence of both simulated data and real data. The results show that the proposed algorithm has the advantage of speed, and the strategy of regional extension can efficiently identify stars in large FOV images compared with other existing algorithms.     

沿空切顶成巷段巷道围岩变形规律研究

以宏景塔一矿回采工作面为研究对象,基于切顶卸压无煤柱自动成巷技术原理,采用数值模拟计算和现场实测的方法,对该矿成巷段巷道围岩支承压力分布及围岩变形规律进行分析。研究结果表明:随着工作面向前推进,巷道围岩支承压力呈先增大后减小最后趋于稳定的变化趋势,支承压力稳定值为13.5 MPa;受工作面回采动压的影响,距离工作面70 m以内,锚索受力急剧增大到恒阻值、巷道围岩变形明显;距离工作面70~150 m,锚索受力迅速减小、巷道围岩变形逐渐变缓;在距离工作面150 m之后,锚索受力仅有微量变化、巷道围岩变形趋于稳定。因此确定支护体回撤保守安全位置为工作面后方150 m。工程实践表明:所设支护体回撤距离能够应对巷道围岩变形,成巷效果良好。     

高层建筑中上下相邻双层大跨度钢桁架施工技术

介绍了上海前滩10-01地块(办公及住宅)高层建筑上下相邻双层大跨度钢桁架施工技术。结合项目桁架结构特点,分析讨论了双层桁架的支撑措施布设及安装过程中的注意要点,解决了±0m楼板不能满足双层桁架荷载要求的问题,提出了待下层桁架支撑卸载后,利用下层桁架布设上层桁架支撑,完成上层桁架安装的方案。同时通过有限元计算分析,对桁架施工过程进行计算模拟,研究施工过程的结构位形及内力,保证施工质量与安全。