PC基光散射材料的制备研究

将丙烯酸、有机硅光扩散等助剂混合后,经过平行双螺杆挤出机制备了光扩散聚碳酸酯,研究不同配比的丙烯酸和有机硅光扩散剂对聚碳酸酯光学性能的影响。结果表明:采用不同含量的丙烯酸和有机硅光扩散剂复配,添加不同的量可得到不同光学性能的光扩散聚碳酸酯。     

电磁轨道驱动活塞式混凝土泵的建模及特性分析

为了提高混凝土泵性能,提出电磁轨道驱动活塞式混凝土泵的新型驱动方式,为活塞式混凝土泵的驱动方式开辟了新的途径。基于基尔霍夫定律以及相关电学知识,建立了电路特性方程;对系统运动过程进行了动力学分析,建立了活塞运动特性方程;基于MATLAB/Simulink建立了系统工作的仿真模型,分析了泵送距离不同时活塞的运动特性,得出在400 kA幅值的正弦交流电条件下,4种泵送距离工况中,200 m与250 m为最佳;回泵时,3种电源参数条件下,幅值为35 kA的正弦交流作为馈入电流最宜。仿真结果体现了电磁轨道驱动系统设计方案的有效性;为电磁轨道驱动混凝土泵系统的设计提供了理论依据。     

Application of GaN-based ultraviolet-C light emitting diodes--UV LEDs--for water disinfection

GaN-based ultraviolet-C (UV-C) light emitting diodes (LEDs) are of great interest for water disinfection. They offer significant advantages compared to conventional mercury lamps due to their compact form factor, low power requirements, high efficiency, non-toxicity, and overall robustness. However, despite the significant progress in the performance of semiconductor based UV LEDs that has been achieved in recent years, these devices still suffer from low emission power and relatively short lifetimes. Even the best UV LEDs exhibit external quantum efficiencies of only 1-2%.The objective of this study was to investigate the suitability of GaN-based UV LEDs for water disinfection. The investigation included the evaluation of the performance characteristics of UV LEDs at different operating conditions as well as the design of a UV LED module in view of the requirements for water treatment applications. Bioanalytical testing was conducted using Bacillus subtilis spores as test organism and UV LED modules with emission wavelengths of 269 nm and 282 nm.The results demonstrate the functionality of the developed UV LED disinfection modules. GaN-based UV LEDs effectively inactivated B. subtilis spores during static and flow-through tests applying varying water qualities. The 269 nm LEDs reached a higher level of inactivation than the 282 nm LEDs for the same applied fluence. The lower inactivation achieved by the 282 nm LEDs was compensated by their higher photon flux. First flow-through tests indicate a linear correlation between inactivation and fluence, demonstrating a well designed flow-through reactor. With improved light output and reduced costs, GaN-based UV LEDs can provide a promising alternative for decentralised and mobile water disinfection systems.     

LED直流灯具在太阳能户用电源系统中的应用研究

本文通过性能测试对LED直流灯具与荧光灯的系统设计进行对比,并分析了电压波动及高原性气候对LED直流灯具的影响,进而研究了LED直流灯具在太阳能户用电源系统中的适用性。     

LED在照明工程中的应用及安装应注意的事项

本文通过工程实际阐述LED光源特点、发展趋势以及LED在照明工程中的应用和LED照明产品在工程安装中应注意的事项。     

夯扩桩的设计应用研究

夯扩桩作为一种经济桩型,即使在今后相当长一段时间内仍具使用价值,但存在该用夯扩桩时工程技术人员却怕用的现象。因此,本文根据作者对大量工程设计与施工实践的积累总结,就夯扩桩的正确设计方法进行了一些分析探讨。强调了夯扩桩设计时应着重注意的一些问题,并针对一些观点提出了见解及分析,以期利于工程设计实践。     

论都市圈的整体性、成长动力及中国都市圈的发展态势

都市圈不同于一般的城市地区,也不同于一个个单体城市,而是有着自身的特点和形成与演化规律。本文从都市圈的内涵出发,探讨了有关都市圈的若干理论,包括都市圈的五种整体效应:集聚效应、规模效应、结构效应、成本效应和品牌效应;在此基础上分析了都市圈形成的三种要素:区位因素、基础设施和人文要素,以及都市圈成长的四种动力机制:市场机制、制度建设与竞争合作机制。在文章的最后一部分,基于上述有关理论,对中国的都市圈进行了评价和态势分析。     

LED调光控制在人民路隧道照明中的应用

传统隧道照明控制采用"开、关灯控制"模式,上海人民路隧道采用新型光源LED,控制方式也采用了智能化程度较高的调光控制。介绍了人民路隧道照明选用LED调光控制的原因、调光控制系统架构、LED灯具调光原理以及应用的关键技术及指标等,同时对隧道LED调光运营模式提出了建议,分析了节能效果。LED是今后照明的发展方向,LED调光控制是其重要组成部分。     

基于学习成效驱动的暖通专业研究生课程多元化考核方法研究与实践

哈尔滨工业大学暖通学科为研究生开设了基础课、专业基础课和专业课。针对不同类型课程的特点,提出了“期末考试+课程论文+报告答辩”“课堂内容考核+课外阅读考核+综述论文+案例论文+课堂提问+专题讨论”“开卷考试+研究报告+加分计分”“上机实践+研究报告”“课程论文+课堂练习+工程案例分析交流”等多元化的考核方式,注重过程管理。介绍了多元化考核模式及其在暖通学科不同类型课程改革中的应用,以期对其他工科类研究生课程考核提供借鉴。     

Site-selective occupation and luminescence property investigation of Ca18Na3Y(PO4)14:Eu2+ phosphor for full-spectrum LED

Cyan-emitting phosphors have attracted widespread attention as an integral part to realize full-spectrum lighting. Understanding the site occupation of luminescence centers is of great importance to design and clarify the luminescent mechanism for new cyan-emitting phosphors. Here, we report a cyan-emitting phosphor Ca₁₈Na₃Y(PO₄)₁₄:Eu²⁺ synthesized by the high-temperature solid-state method. The crystal structure is characterized by X-ray diffraction and refined by the Rietveld method. The diffuse reflectance spectra, excitation/emission spectra, fluorescence decay curves, thermal stability, and related mechanism are systematically studied. The results show that Ca₁₈Na₃Y(PO₄)₁₄:Eu²⁺ crystallizes in a trigonal crystal system with space group R3c. Under excitation at 350 nm, a broadband cyan emission can be obtained at 500 nm with a half-width of about 120 nm, which is caused by Eu²⁺ occupying five different sites in host, namely, Na2O₁₂ (450 nm), (Ca3/Na1)O₈ (485 nm), Ca2O₈ (515 nm), Ca1O₇ (565 nm), and (Ca4/Y)O₆ (640 nm), respectively. Moreover, crystal structure, room and low temperature spectroscopy, and luminescence decay time are used to skillfully verify the site-selective occupation of Eu²⁺. Finally, a full-spectrum light-emitting diode (LED) lamp is fabricated with an improved color rendering index (∼90.3), CCT (∼5492 K), and CIE coordinates (0.332, 0.318). The results show that Ca₁₈Na₃Y(PO₄)₁₄:Eu²⁺ has the potential to act as a cyan emission phosphor for full-spectrum white LEDs.