一种不同地面分辨率图像的拼接算法

航空遥感监测中变焦镜头的广泛应用以及飞行高度的变化会获得不同地面分辨率的航空影像,因此为了实时监控到飞行区域的整体情况,需要对不同地面分辨率的图像进行拼接。提出了针对不同地面分辨率图像进行拼接的方法。首先用四分法对图像进行分割,检测变化倍率,选择配准策略;然后用基于加速鲁棒性特征(Speeded-Up Robust Features,SURF)的算法对相邻图像进行拼接。获得了焦距变化从高倍过渡到低倍,或从低倍过渡到高倍的拼接图像。通过航空变焦模拟影像的拼接实验和地面变焦影像的拼接实验表明,该方法能够对不同地面分辨率的图像进行拼接,且拼接结果均以高分辨率为基准。     

基于毛竹叶片理化参数的刚竹毒蛾危害检测研究

虫害检测算法研究是开展虫害快速、准确监测，制定精准森防检疫措施的重要基础。以毛竹叶片为研究尺度，基于刚竹毒蛾危害下的寄主外部形态与内部生理现象总结，选择并实测叶损量LL、相对叶绿素含量RCC、相对含水量RWC、原始光谱的733.66~898.56 nm值(ρ_{733.66~898.56})、一阶微分光谱的562.95~585.25 nm值(ρ′_{562.95~585.25})与706.18~725.41 nm值(ρ′_{706.18~725.41})等理化参数，随机划分实验组(63组)和验证组(37组)并设计5次重复实验；分别运用Fisher判别分析、BP神经网络、随机森林等三种方法建立刚竹毒蛾危害等级的检测模型，从检测精度、Kappa系数及R2等指标对模型的检测效果予以分析和比较。结果显示，Fisher判别分析、BP神经网络、随机森林的检测精度分别为69.19%，65.41%，83.78%，Kappa系数分别为0.576 9，0.532 4和0.778 8，R2分别为0.722 2，0.582 6和0.870 9，总体而言，三种方法均具备刚竹毒蛾危害的检测能力，随机森林的检测效果最优，Fisher判别分析次之，再次为BP神经网络；从分等级来看，随机森林的检测精度亦优于Fisher判别分析与BP神经网络，但3种方法对中度危害等级的检测精度均有所不足。该成果可为刚竹毒蛾危害及其他病虫害检测算法的选择提供参考，并为进一步建立冠层、遥感影像像元等尺度的虫害检测模型奠定基础。     

Comparison of microwave‐assisted and conventional extraction of mangiferin from mango (Mangifera indica L.) leaves

Mangiferin is the main bioactive component in mango leaves, which possesses anti‐inflammatory, antioxidative, antidiabetic, immunomodulatory, and antitumor activities. In the present study, a microwave‐assisted extraction method was developed for the extraction of mangiferin from mango leaves. Some parameters such as ethanol concentration, liquid‐to‐solid ratio, microwave power, and extraction time were optimized by single‐factor experiments and response surface methodology. The optimal extraction conditions were 45% ethanol, liquid‐to‐solid ratio of 30:1 (mL/g), and extraction time of 123 s under microwave irradiation of 474 W. Under optimal conditions, the yield of mangiferin was 36.10 ± 0.72 mg/g, significantly higher than that of conventional extraction. The results obtained are beneficial for the full utilization of mango leaves and also indicate that microwave‐assisted extraction is a very useful method for extracting mangiferin from plant materials.     

Survey study and experimental investigation on the local behavior of pedestrian groups

Current research on pedestrian dynamics mainly focuses on the interactions among isolated individuals, the impact of the presence of groups is not fully considered. In recent 5 years, researchers have started to investigate pedestrian group movement. The aim of this work is to explore the local behavior of pedestrian groups by questionnaires and field observation. Survey study focused on pedestrians' psychology when walking in groups, which included five parts: group size, interpersonal distance, spatial relationship among group members, speed adjustment of group members, information transmission, and acid action among group members. Meantime a field observation was carried out to study group movement characteristics, which contained speed, step frequency, offset angle and interpersonal distance. The survey results show that group members have a closer interpersonal distance, faster information transmission and plenty of acid action. Conversely, group walking has a negative influence on pedestrian's speed, step frequency by comparing with the way isolated pedestrian walks. In addition, it is found that for a certain group, the group members are able to keep movement consistent. Also there exists obvious movement diversity among different group types (male dyads, female dyads, couple groups, and ordinary‐friend groups) because of different gender and social relationship. Ultimately the results will be more promising for helping to model the movement of pedestrian groups. © 2014 Wiley Periodicals, Inc. Complexity 20: 87–97, 2015     

Comparative Analysis of Chemical Constituents in Different Parts of Lotus by UPLC and QToF-MS

Six parts of lotus (seeds, leaves, plumule, stamens, receptacles and rhizome nodes) are herbal medicines that are listed in the Chinese Pharmacopoeia. Their indications and functions have been confirmed by a long history of clinical practice. To fully understand the material basis of clinical applications, UPLC-QToF-MS combined with the UNIFI platform and multivariate statistical analysis was used in this study. As a result, a total of 171 compounds were detected and characterized from the six parts, and 23 robust biomarkers were discovered. The method can be used as a standard protocol for the direct identification and prediction of the six parts of lotus. Meanwhile, these discoveries are valuable for improving the quality control method of herbal medicines. Most importantly, this was the first time that alkaloids were detected in the stamen, and terpenoids were detected in the cored seed. The stamen is a noteworthy part because it contains the greatest diversity of flavonoids and terpenoids, but research on the stamen is rather limited.     

Piper betle (L): Recent Review of Antibacterial and Antifungal Properties,Safety Profiles,and Commercial Applications

Piper betle (L) is a popular medicinal plant in Asia. Plant leaves have been used as a traditional medicine to treat various health conditions. It is highly abundant and inexpensive, therefore promoting further research and industrialization development, including in the food and pharmaceutical industries. Articles published from 2010 to 2020 were reviewed in detail to show recent updates on the antibacterial and antifungal properties of betel leaves. This current review showed that betel leaves extract, essential oil, preparations, and isolates could inhibit microbial growth and kill various Gram-negative and Gram-positive bacteria as well as fungal species, including those that are multidrug-resistant and cause serious infectious diseases. P. betle leaves displayed high efficiency on Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa, Gram-positive bacteria such as Staphylococcus aureus, and Candida albicans. The ratio of MBC/MIC indicated bactericidal and bacteriostatic effects of P. betle leaves, while MFC/MIC values showed fungicidal and fungistatic effects. This review also provides a list of phytochemical compounds in betel leaves extracts and essential oils, safety profiles, and value-added products of betel leaves. Some studies also showed that the combination of betel leaves extract and essential oil with antibiotics (streptomycin, chloramphenicol and gentamicin) could provide potentiating antibacterial properties. Moreover, this review delivers a scientific resume for researchers in respected areas and manufacturers who want to develop betel leaves-based products.     

Different charging behaviors between electrons and holes in Si nanocrystals embedded in SiN_x matrix by the influence of near-interface oxide traps

Si-rich silicon nitride films are prepared by plasma-enhanced chemical vapor deposition method,followed by thermal annealing to form the Si nanocrystals(Si-NCs)embedded in Si Nx floating gate MOS structures.The capacitance–voltage(C–V),current–voltage(I–V),and admittance–voltage(G–V)measurements are used to investigate the charging characteristics.It is found that the maximum flat band voltage shift(△VFB)due to full charged holes(～6.2 V)is much larger than that due to full charged electrons(～1 V).The charging displacement current peaks of electrons and holes can be also observed by the I–V measurements,respectively.From the G–V measurements we find that the hole injection is influenced by the oxide hole traps which are located near the Si O2/Si-substrate interface.Combining the results of C–V and G–V measurements,we find that the hole charging of the Si-NCs occurs via a two-step tunneling mechanism.The evolution of G–V peak originated from oxide traps exhibits the process of hole injection into these defects and transferring to the Si-NCs.     

城市化进程中上海植被的多样性、空间格局和动态响应（Ⅶ）： 上海浦东近自然森林十年间的动态变化及模式优化

以2000年在上海浦东新区营建的近自然森林为研究对象,通过对群落种类组成、植株密度、植株高度、胸径和土壤养分的跟踪调查,研究了近自然森林十年间的动态变化.结果表明：经过10 年生长,林分长势良好,植物种类组成基本上仍以初期种植的物种为主,伴有少量自然侵入种;由于建设前期缺乏荫蔽,苦槠（Castanopsis sclerophylla）、红楠（Machilus thunbergii）等常绿阔叶树种枯死较多,枫香（Liquidambar formosana）和女贞（Ligustrum lucidum）死亡率低、生长迅速,逐渐占据群落上层后,常绿阔叶树种逐渐适应群落环境,趋于稳定生长;随着群落的发展近自然森林土壤养分较种植初期稳定上升.针对存在的问题,结合近自然森林优化模式建设的尝试,提出了“异龄复层落叶—常绿混交林”的种植模式,为城市地标性的植物群落构建提供指导与参考.