Light-emitting diodes (LEDs) have been regarded as the best artificial source of light for a plant factory. However, the effect of light quality on seedling production in such environments requires further study. On the basis of the practical application of light on cucumber seedlings (Ansha Company) in plant factories, the present investigation tracked and recorded the specific effects of red and blue light on the growth of the seedlings by analyzing the photo-biological mechanism involved. The growth parameters, as well as the photosynthetic characteristics of cucumber seedlings, were measured at different variations of light quality. The results showed that when the proportion of red light in the light source was higher than blue light, the height of the seedlings, leaf size, stem diameter, Dixon Quality Index (DQI), relative chlorophyll content, and the net photosynthetic rate were higher than those of the experimental group with a relatively high proportion of blue light. In the case of R7B3 (70% red light and 30% blue light), the stem diameter, DQI, and net photosynthetic rate of seedlings were 14%, 57%, and 22% higher than the minimum value, respectively. The present study analyzed the influence of red and blue light on plant growth characteristics during actual production and provides standardization for it.

The quality of tea is relative with its concentration. In this paper, we present a method to identify the concentration of tea based on Tyndall effect. The tea is illuminated by 3-watt LED light sources with the main wavelength in ultraviolet and visible bands. The intensities of transmitted light are detected using the distributed photometer and the images of light distribution are captured by CCD camera at vertical direction to observe the Tyndall effect. The intensities and images for different light sources are compared. The experimental results show that there exist Tyndall phenomenon in tea. In addition, the Tyndall effect becomes weaker as the tea concentration increases when the tea is illuminated by the LED light sources with the main wavelength in the ultraviolet band. The method presented in this paper should be helpful for rapid identification of the tea quality

随着社会的发展,大型机场的任务繁重且日益增多,以及机场的人工技术弊端日益凸显,为实现智能化管理大型机场,改善出现的问题,目前已有部分机场引入物联网技术.因为利用物联网技术能够更加便于管理,所以该技术在建设一个安全、绿色且节约人工的智慧机场时起到重要作用.以浦东国际机场智慧场区为例,介绍智慧机场的水质在线监测系统,该系统采用4G、窄带互联网(NB-IoT)、光纤、全球定位系统(GPS)等物联技术来进行精准的建设布局,实现水质信息的数据采集、数据处理以及实时传输等管理目标.

With the rapid development of LED technology, the lighting effect of LED lamp belt in the atmosphere lamp has been unable to meet the needs of the modern market, and the COB lamp belt has gradually entered the public field of vision due to its advantages of high light uniformity, low junction temperature and large luminous Angle. In this paper, the stability, light uniformity, junction temperature and other performance of the two kinds of lamp belt under different color temperature and different power were analyzed by setting contrast experiment. It was found that LED lamp belt had uniform light and poor heat dissipation effect due to chip distribution characteristics, and it would accumulate a lot of heat and appear color shift phenomenon when continuously lit. The COB lamp belt can not only maximize the heat dissipation performance of the substrate, but also achieve more uniform light distribution by the way of multi-chip arrangement. The relationship between the thermal performance and chip spacing is analyzed by optimizing the design, which plays a guiding role in the actual production of the lamp belt

There is an obvious colloid state in sauce-flavor liquor due to its unique brewing process and long storage time, which is an important quality feature of sauce-flavor. Aiming at the problems of time, cost, and the strong professionalism of the traditional quality identification method, we proposed a method to identify the quality of sauce-flavored liquor based on the Tyndall phenomenon. The influence of different wavelengths of light on the light scattering in liquor was explored, and it was concluded that the ultraviolet and blue light bands have a certain efficiency in the identification of liquor. Additionally, we analyzed the relationship between the particle size uniformity of liquor colloids and liquor quality according to the Tyndall phenomenon. We found that higher quality liquor has a brighter and lighter Tyndall path and a smaller light flooding angle due to the uniformity of the particles in it. This method can be used to achieve qualitative identification and is suitable for the identification of sauce-flavored liquor.

倒装LED芯片克服了正装LED芯片的不足,提高了 LED器件的可靠性和使用寿命.在实际生产过程中,焊接工艺是倒装芯片封装过程中的关键步骤,倒装LED芯片互连界面的可靠性被认为是最重要的可靠性问题之一.随着微电子封装的发展和焊点使用环境的日益特殊,对无铅焊料的性能提出了更加严格的要求.由于小尺寸效应和高表面能,纳米颗粒已被广泛用于改善无铅焊料的微观结构和性能.因此,含有纳米颗粒的复合焊料最近引起了广泛关注.本文回顾了近年来对SnAgCu复合焊料合金的研究,并介绍了纳米颗粒对其微观结构、机械性能、润湿性和可靠性的影响.分析总结了纳米粒子强化的机理.此外,还讨论了纳米颗粒增强无铅焊料的不足和未来发展趋势,希望为这些复合焊料在封装中的应用提供一定的理论参考.

在分析智慧物联系统需求的基础上,阐述了红外光学雨量实时监测技术对智慧机场雨量实时监测系统的保障作用.介绍了雨量测量技术及具有代表性的雨量计,然后介绍了红外光学雨量计的工作原理,并对该雨量计在智慧机场中的应用给出了方案分析.

The effect of correlated color temperature (CCT) on the thermal performance of light emitting diode (LED) filament in flip-chip packaging was investigated in detail. Two filaments with different lengths were selected as the research object, and the thermal resistance of filaments under three CCT (2200 K, 2400 K, 2700 K) were studied. The optical properties and thermal parameters of the two groups of filaments were measured, and the results were analyzed combined with the color coordinate. The experimental results show that thermal properties of LED filaments is closely related to CCT. Under constant current condition, junction temperature decreases with the increase of color difference. With the change of phosphor glue and phosphorus powder ratio, the color temperature of LED filament also changes. In the filaments with the same chip structure and packaging mechanism, the higher the proportion of red phosphorescent powder, the worse the heat dissipation performance of the filament. These results show that in the design and manufacture of LED filament, it is helpful to control the CCT of LED filament under the premise of meeting the use requirements.

This article focuses on the study of voids in the solder joint interface of flip-chip LEDs. Additional flux is added to the solder paste to reduce the frequency of voids, and the mechanical properties of the solder joints are compared and analyzed. Two kinds of fluxes (NC559-TPF, TSF-6516) are selected. They are used in two kinds of solder pastes (lead and lead-free solder paste). The amount of flux added is 0 mL, 0.4 mL, and 0.8 mL. The other preparation conditions for all combinations are the same and are within the recommended scope of the manufacturer's documentation. X-rays are used to detect and analyze the distribution and quantity of voids in the solder layer. A push–pull tester is used to analyze and evaluate the mechanical strength of the solder joints. A scanning electron microscope was used to observe the microscopic morphology of the cross-section of the solder joint and the fracture morphology of the interface after the shear test. It was found that adding a proper amount of high-activity flux to the solder paste can reduce the frequency of voids and improve the mechanical reliability of the solder joints. Finally, we tested the thermal performance of the flip-chip LED filament for verification.

随着物联网和智能控制技术的高速发展,照明行业正由原来的机械化控制向智能化、系统化方向转移,智能化产品开始不断涌入市场.标准是一种引导和规范行业发展的文件,也是作为行业发展的技术支撑,对国家政策、行业的发展以及消费者都会产生很大的影响.本文对目前相关的智能照明标准进行解读,为全面掌握智能照明标准化现状、完善智能照明标准化体系及智能照明产业发展保驾护航提供参考.

This article mainly studies the thermal characteristics of light source of the street lamp, and systematically analyzes the effective ways of heat transfer and heat dissipation of street lamp. Based on experiments and finite element simulations, the heat dissipation channels of street lights were studied, and the weak links of heat transfer and heat dissipation were analyzed, and the heat dissipation structure of street lamp was optimized. The experimental results show that the junction temperature of the chip is lower than 90 °C in the steady state, and the luminous efficiency decreases by 5.93%. In order to ensure the efficiency and reliability of the street lamp, it is recommended that the junction temperature of the street lamp be controlled below 85 °C. After analyzing the arrangement of the chips, silicone grease with different thermal conductivity and aluminum substrate, it is found that the substrate is the bottleneck affecting effective heat transfer, and the use of diamond like carbon metal core printed circuit board (DLC-MCPCB) can reduce the junction temperature by 17.04 °C. Through the grid design of shell of the street lamp, the heat dissipation effect of the street lamp surface can be enhanced, and the junction temperature can be reduced by 7.04 °C. Based on these studies, the optimal design model of street lamp was obtained, which provides guidance for practical applications.

针对市面上LED植物补光灯波长单一的问题,采用多色LED集成芯片设计了一种LED植物补光灯.建立了植物灯的三维模型,并利用有限元软件FloEFD对其进行热学模拟.在保证光照均匀的条件下,分析散热板安装方向、外壳开孔、风扇风向、翅片高度等对散热性能的影响,对散热结构进行优化设计并制作了LED植物补光灯实物.优化后的植物补光灯适用于室内植物补光,对植物灯的散热设计具有一定指导意义.

随着绝缘栅双极晶体管(IGBT)向高功率和高集成度方向发展,在结构和性能上有很大的改进,热产生问题日益突出,对散热的要求越来越高,IGBT芯片是产生热量的核心功能器件,但热量的积累会严重影响器件的工作性能.因此,对IGBT模块的温度进行有效地检测和管理是十分重要的环节.综述了IGBT模块的研究现状、研究热点以及散热相关技术,主要介绍了主动散热和被动散热的方法、以及IGBT功率模块的热阻网络系统和散热系统设计的主要步骤,和减小热阻来增强散热的方法.