Loop Closure Detection Algorithm Based on Greedy Strategy for Visual SLAM

动态环境与视觉混淆严重影响视觉闭环检测性能.基于贪心策略,提出了一种在线构建视觉词典的闭环检测算法.算法优先处理Surf描述与已有单词Surf描述欧式距离最大的特征点,改进特征点与单词Surf描述最近邻的约束条件,生成了表征性能强、量化误差小的视觉词典,算法具备实时性,并在动态环境图像集与视觉混淆多发生的图像集上,在确保100%,准确率的条件下,最大召回率分别提升了5%,与4%,.The performance of loop closure detection is seriously affected by dynamic objects and perceptual aliasing in the environment. Based on greedy strategy, a real-time loop closure detection approach using online visual dictionary is proposed. The process of dictionary construction gives priority to dealing with Surf feature that has the maximum Euclidean distance from the closest vocabulary word. A more discriminative and representative visual vocabulary is produced through adding constraint condition to the nearest neighbor distance. This visual vocabulary guarantees a small quantization error. The proposed approach meets real-time constraints. Experiments based on datasets from dynamic environments and visually repetitive environments demonstrated that the largest recall rate increased by 5% and 4% respectively at 100% precision. © 2017, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.国家自然科学基金资助项目(61274133). Supported by the National Natural Science Foundation of China(61274133

Loop Closure Detection Algorithm Based on Greedy Strategy for Visual SLAM

动态环境与视觉混淆严重影响视觉闭环检测性能.基于贪心策略,提出了一种在线构建视觉词典的闭环检测算法.算法优先处理Surf描述与已有单词Surf描; 述欧式距离最大的特征点,改进特征点与单词Surf描述最近邻的约束条件,生成了表征性能强、量化误差小的视觉词典,算法具备实时性,并在动态环境图像集; 与视觉混淆多发生的图像集上,在确保100%,准确率的条件下,最大召回率分别提升了5%,与4%,.The performance of loop closure detection is seriously affected by; dynamic objects and perceptual aliasing in the environment.Based on; greedy strategy,a real-time loop closure detection approach using online; visual dictionary is proposed.The process of dictionary construction; gives priority to dealing with Surf feature that has the maximum; Euclidean distance from the closest vocabulary word.A more; discriminative and representative visual vocabulary is produced through; adding constraint condition to the nearest neighbor distance.This visual; vocabulary guarantees a small quantization error.The proposed approach; meets real-time constraints.Experiments based on datasets from dynamic; environments and visually repetitive environments demonstrated that the; largest recall rate increased by 5%, and 4%, respectively at 100%,; precision.国家自然科学基金资助项

小槐花的化学成分研究

目的:系统研究中药小槐花中的化学成分。方法:利用大孔树脂,Sephadex LH-20,ODS及正相硅胶柱等色谱手段进行分离,通过多种波谱学数据分析进行化合物的结构鉴定。结果:从小槐花60%乙醇提取物中分离得到15个化合物,经结构鉴定分别为豆甾醇(1),β-谷甾醇(2),柠檬酚(3),黄槿酮A(4),异柠檬酚(5),kenusanone I(6),neophellamuretin(7),清酒缸酚(8),古柯三醇(9),黄槿酮D(10),山柰酚(11),8-prenylquercetin(12),leachianone G(13),5,7,4'-三羟基-二氢黄酮醇(14),4H-1-benzopyran-4-one,2-(3,4-dihydroxyphenyl)-2,3-dihydro-3,5,7-trihydroxy-8-(3-methyl-2-butenyl)-,(2R-trans)-(9CI)(15)。结论:除化合物8外,所有化合物均为从该种植物中首次分离得到

韓日 設備戰略 比較硏究 -電子/纖維産業을 中心으로

1992-06최근에 제기되고 있는 한국경제의 위기상황과 관련하여 제조기업의 경쟁력 약화가 큰 문제점으로 대두되고 있다. 가장 건정하고 오래 지속될 수 있는 경쟁우위는 제조부문에서 나온다는 사실로부터 생산전략의 중요성이 학제와 실무계에 재인식되고 있다. 情報化社會의 진전이 본격적으로 이루어짐에 따라 시장과 고객의 성격이 달라지고, 이에 대처하는 기업의 경쟁방식에 있어서도 많은 변화가 요구되고 있는 것이 현실이다. 본 연구는 90년대, 나아가 그 이후의 기업환경을 전망하고, 이에 대처하는 제조기업 설비전략의 전개방향을 모색하기 위한 한일 비교연구를 시도하였다

GaAs/AlGaAs量子级联激光器

利用分子束外延方法生长了激射波长约为9μm的GaAs/Al0.45Ga0.55As量子级联激光器.条宽35μm,腔长2mm的器件准连续激射温度最高达120K,81K下未经收集效率修正的峰值功率超过70mW

7.8μm二级分布反馈量子级联激光器

报道了基于应变补偿的InP基In0.53+xGa0.47-xAs/In0.52-yAl0.48+yAs分布反馈量子级联激光器.采用二级光栅作为反馈,激射工作波长为7.8μm,在1%占空比,5kHz频率的工作条件下,在93～173K的温度范围内,单模发射光谱边模抑制比均超过20dB,调谐系数dλ/dT=0.5125nm/K.在93K时,峰值功率为30mW,直到153K时,峰值光功率仍达到12mW

长期禁食对尿酸代谢的影响及其调控机制探讨

为研究长期禁食过程中大鼠尿酸代谢的变化及其潜在的调控机制，以Sprague-Dawley（SD）大鼠为动物模型，通过病理组织切片、生化检测、荧光定量PCR（qRT-PCR）以及蛋白免疫印迹（Western blotting）等方法分析不同禁食时间（1，2，3，5，7天）大鼠尿酸水平及其代谢相关基因和蛋白的表达变化。结果表明，长期禁食未对大鼠肾脏组织产生明显的损伤，引起了血尿酸水平上升、尿尿酸水平波动性变化和血液尿酸酶活性升高；随着禁食时间的延长，主要尿酸转运蛋白的mRNA和蛋白表达水平逐渐上调。长期禁食过程中大鼠尿酸代谢变化可能与尿酸转运蛋白及尿酸酶活性有关

作業現場問題點分析與改善研究－以通鷾公司為例

出處：真理大學工管

短腔长单模量子级联激光器

报道了激射波长为5．4和7．84μm的应变补偿In1-xGaxAs／In1-yAlyAs量子级联激光器的单模激射．以高质量的应变补偿量子级联激光器材料为支撑，通过减小FP腔长，开辟实现单模器件的新途径．首次实现阈值电流仅为50mA、腔长为145μm的激射波长在λ≈5．4μm的单模激射和阈值电流仅为80mA、腔长为170μm的激射波长在λ≈7．84um的单模激射．这是目前InGaAs／InAlAs材料体系最短腔长的边发射量子级联激光器