一种用于光照快速改变光伏MPPT控制算法

最大功率点跟踪技术(MPPT)被广泛用在光伏发电系统中,根据光伏电池的特性,提出一种具有光照环和温度环的新型MPPT控制算法,并且优化了系统的启动性能。Matlab仿真结果表明该方法能够快速启动,同时当外界大气环境剧烈变化的时候,能够快速、准确地跟踪光伏阵列的最大功率点,并且减小最大功率点处的振荡,减小功率损失。

Tomato detection method using domain adaptive learning for dense planting environments

This study aimed to address the challenge of accurately and reliably detecting tomatoes in dense planting environments,a critical prerequisite for the automation implementation of robotic harvesting.However,the heavy reliance on extensive manually annotated datasets for training deep learning models still poses significant limitations to their application in real-world agricultural production environments.To overcome these limitations,we employed domain adaptive learning approach combined with the YOLOv5 model to develop a novel tomato detection model called as TDA-YOLO(tomato detection domain adaptation).We designated the normal illumination scenes in dense planting environments as the source domain and utilized various other illumination scenes as the target domain.To construct bridge mechanism between source and target domains,neural preset for color style transfer is introduced to generate a pseudo-dataset,which served to deal with domain discrepancy.Furthermore,this study combines the semi-supervised learning method to enable the model to extract domain-invariant features more fully,and uses knowledge distillation to improve the model's ability to adapt to the target domain.Additionally,for purpose of promoting inference speed and low computational demand,the lightweight FasterNet network was integrated into the YOLOv5's C3 module,creating a modified C3_Faster module.The experimental results demonstrated that the proposed TDA-YOLO model significantly outperformed original YOLOv5s model,achieving a mAP(mean average precision)of 96.80%for tomato detection across diverse scenarios in dense planting environments,increasing by 7.19 percentage points;Compared with the latest YOLOv8 and YOLOv9,it is also 2.17 and 1.19 percentage points higher,respectively.The model's average detection time per image was an impressive 15 milliseconds,with a FLOPs(floating point operations per second)count of 13.8 G.After acceleration processing,the detection accuracy of the TDA-YOLO model on the Jetson Xavier NX development board is 90.95%,the mAP value is 91.35%,and the detection time of each image is 21 ms,which can still meet the requirements of real-time detection of tomatoes in dense planting environment.The experimental results show that the proposed TDA-YOLO model can accurately and quickly detect tomatoes in dense planting environment,and at the same time avoid the use of a large number of annotated data,which provides technical support for the development of automatic harvesting systems for tomatoes and other fruits.

基于meso-位置含有S原子的醌式Bisanthene衍生物的合成与性质表征

在醌式Bisanthene的meso-位置嵌入杂原子S,然后对其光电性质进行研究。原料9-噻吨酮和劳森试剂反应得到硫酮(Ⅲ),接着和水合肼缩合成酮腙(Ⅳ),其后被氧化得到相应的重氮化合物,该产品直接和Ⅲ通过Barton-Kellogg反应制备环硫化合物Ⅴ,接着被Cu粉还原生成烯烃前体Ⅵ。最后对Ⅵ进行Katz-modified Mallory光关环来合成Ⅰ。由于单边关环产物Ⅶ不具有均苯乙烯类结构骨架,不能进一步发生光关环得到目标产物Ⅰ。化合物Ⅶ和Ⅵ相比,表现出扩展的π体系,自身的最大吸收波长红移105 nm,发射波长红移90 nm。另外,电化学测试表明Ⅶ可以被可逆的氧化为阳离子,且被扩展的π体系所稳定。由此推测,目标产物I具有更大的π体系,更长范围的吸收及发射波长,较低的Eg、更多级的可逆氧化电位。

查尔酮合成黄酮化合物的研究进展

综述了近年来各种经查尔酮环化合成黄酮化合物的反应体系、合成方法,介绍了各种反应体系的适用范围,指出了各自的优缺点及其合成黄酮化合物的产率范围,认为黄酮化合物的合成将以新技术、新方法和无污染的绿色合成为发展方向。

Night Vehicle Detection Using Variable Haar-Like Feature

This paper proposes a night-time vehicle detection method using variable Haar-like feature.The specific features of front vehicle cannot be obtained in road image at night-time because of light reflection and ambient light,and it is also difficult to define optimal brightness and color of rear lamp according to road conditions.In comparison,the difference of vehicle region and road surface is more robust for road illumination environment.Thus,we select the candidates of vehicles by analysing the difference,and verify the candidates using those brightness and complexity to detect vehicle correctly.The feature of brightness difference is detected using variable horizontal Haar-like mask according to vehicle size in the location of image.And the region occurring rapid change is selected as the candidate.The proposed method is evaluated by testing on the various real road conditions.

Fruit protected cultivation in China

Protected fruit cultivation in China has developed very quickly from the early 1990s, and now it is an important branch in fruit cultivation. A brief review including fruit species, developing history, growing area, output, and distribution in the whole country is made in the paper. Characteristics of the dominant kinds of greenhouse, environmental control methods, and standards of temperature, humidity, light and CO2 for different fruit species are presented. Information on varieties, growing benefits, special management practices and other aspects of the main fruit species used for protected cultivation are also presented.

Effect of temperature and photoperiod on maturation of Cephalothrix hongkongiensis(Nemertea: Palaeonemertea)

The limited knowledge about the relationships between environmental factors and the maturation and reproductive seasonality of nemerteans is mostly obtained from field studies, and in many cases is conjectural. Few species have been studied under well-controlled laboratory conditions. In this work, the effects of temperature and photoperiod on gonad development and spawning of Cephalothrix hongkongiensis were observed by rearing worms under different temperatures and photoperiods. Worms reared at 4~C and 6~C showed no growth or gonadal development, and all died within 109 days. At 8~C and 12~C, gonads could be seen from 90 days to the termination of the 360-day experiment, but no spawning was observed. Worms maintained at 16, 24, and 28~C showed both gonadal development and spawning, and matured faster at higher temperatures. Under a fixed temperature （16℃）, photoperiod did not have any significant impact on maturation and spawning. It is likely that temperature plays a major role in regulating the maturation and reproductive cycle of C. hongkongiensis.

Organic indoor light harvesters achieving recorded output power over 500%enhancement under thermal radiated illuminances

Organic photovoltaic(OPV)cells have found their potential applications in the harvest of indoor light photons.However,the output power of such indoor devices is usually far from the demand of the internet of things.Therefore,it is essential to boost the output power of indoor organic photovoltaics to a much higher level.As wildly deployed among industrial and civil luminous environments,thermal radiation-based indoor light sources are alternative candidates to supply the essential power of the off-grid electronics with a broad consecutive emission spectrum.In this work,we evaluated the photovoltaic performance of organic solar cells under indoor incandescent and halogen illuminations.Impressively,under such thermal radiations,an improvement over 500%of the output power density can be achieved in comparison with that under light-emitting diodes and fluorescent lamps,reaching a record high value of 279.1 lWcm^(-2) by the PM6:Y6-based device.The remarkable power output is originated from the extra near-infrared spectrum of indoor thermal lights,which restricts the effective area under 10 cm^(2) in achieving 1 mW output power.This work clarifies the feasibility of collecting photons radiated from indoor thermal light sources through OPV cells,and enlightens the further applications of indoor OPV cells under multiple illumination environments.

Readily accessible rhodamine B-based photoresponsive material

A photochromic rhodamine B-based material containing Cd（Ⅱ） as bridge was facilely prepared. The 4-methoxylsalicylalde hyde rhodamine B bydrazone Cd（Ⅱ） complex displayed unusual ring-open response upon 365 nm UV irradiation, exhibiting long photochromic lifetime and good fatigue resistance. The UV-induced ring-open of the complex led to a distinct color and fluorescence change in acetonitrile. A new mechanism was put forward： salicylaldehyde part in the complex underwent UV-promoted isomerization from enol-form to keto-form, enhancing the chelation of Cd（Ⅱ） and yielding the ring-opening rhodamine B part. Compared to other reported photochromic systems, this new photochromic material offered attractive new insights into the development of low cost photochromic materials with good performance.

Competition between toxic and nontoxic Microcystis (Cyanophyceae) under different light and temperature conditions

Dear Editor,In aquatic environments,cyanobacteria usually proliferate faster than other phytoplankton assemblages during warm seasons,particularly in eutrophic waters(Ma et al.,2015).Microcystis,a common cyanobacterial genus that potentially produces microcystins(MCs)and nontoxic strains,dominates in eutrophic freshwater bodies,and its biomass increases quickly during the warm period;these changes result in increased water turbidity and changes in light quality and quantity in the water column(Li and Li,2012).Additionally,