Effects of Ozone-Gas Bubble Size and pH on Ozone/UV Treatment

A series of ozone/UV treatment under injection of ozone with different ozone-gas bubble sizes was performed at pH 1.7 and 7.4. The increase in the bubble size and the decrease in pH enhanced the ozone utilization efficiency. The enhancement of ozone utilization efficiency was caused by the shift of the production pathway of hydroxyl radical (OH) from the OH production via O₃ ^– to the UV photolysis of H₂O₂. The lower pH caused this shift through the chemical equilibrium of H₂O₂ and HO₂ ^–, and the large bubbles caused this shift through the augmentation of H₂O₂ transport from the bubble surface to the bulk solution.     

A novel revolving vane compressor with a fixed-vane

This paper presents design improvements of a Revolving Vane (RV) compressor which significantly reduce the frictional losses. The original RV compressor has a vane that swivels during the operation. Though in general, the frictional losses of the RV compressor are significantly lower than most currently available rotary compressors, this swivel vane design has a disadvantage of relatively high vane side friction loss. The latter is caused by a high vane-side and slot contact force due to a high gas pressure differential force across the vane. In this paper, a new design concept has been introduced to totally eliminate the vane side friction loss caused by the gas pressure differential force across the vane. This is achieved by rigidly fixes the vane onto the rotor or the cylinder. This new design yielded two possible variants, each reduces the frictional losses by 18% and 41% and improves the mechanical efficiency from 93% to 94% and 96% respectively. In this paper, details analysis on the new design that leads to the improvement in performance are presented and shown. The analysis also reveals that the design with the highest mechanical efficiency comes with a small price of a higher instantaneous peak torque requirement.     

基于效能优化的山地城市绿地空间研究

随着城市化进程的加快,为缓解 人多、地少、山地多、耕地少的矛盾,越来越 多的城市将山地开发作为城市发展的战略。 本文针对山地城市土地资源紧张,城市建设 开发用地、城市绿地、耕地、自然环境矛盾 突出的现实状况,在梳理国内外现有相关研 究成果的基础上,以效能优化为切入点,引 入“生态智慧”的理念及研究方法,探讨了基 于效能优化的山地城市绿地空间研究的目 的、意义及价值,建构了效能优化的山地城 市绿地空间研究的框架,明确了研究的关键 环节,提出以景观生态学的理念,结合城市 空间发展的动态趋势来认识山地城市绿地 的空间特征,系统性、层次性地建立山地城 市绿地效能评价体系,在城市空间的不同尺 度探索山地城市绿地空间效能优化的原则 和策略是山地城市绿地空间效能优化研究 的重点。     

瓜胶压裂液体系示踪剂的筛选

在油气田开发过程中,多数油气井压裂通常是采取分段压裂,各层段一起合排,此过程目前常用总的返排量来判断整体压裂液的返排效果,而无法了解各个层段压裂液的返排情况。为了评价各层段压裂液的返排效果,可在各层段压裂过程中加入一定浓度的不同示踪剂,在返排时对压裂液返排液进行连续取样,检测返排液中各种示踪剂的浓度,从而判断各层段的返排效果,计算压裂液在地层中的残留量。而在压裂中所用示踪剂需要与压裂液配伍,对油田常用的几种示踪剂进行了实验评价。实验研究结果表明,小分子醇类和无机阴离子(SCN-和Br-)不适合作为瓜胶压裂液示踪剂,2种微量物质TA和TB与瓜胶压裂液配伍,不会对压裂液成胶和破胶产生影响,并且由于其在地层环境中有较低的吸附量,不会对定量测量造成影响,可初步选为压裂液示踪剂。     

Analysis of Magnetic Take-Up Roll Employed in Amorphous Alloy Ribbon Production Line

A novel magnetic take-up roll used in amorphous alloy ribbon formation lines is introduced in this paper. The finite element method was used to calculate two different magnetic models for a selected amorphous ribbon. The simulation result showed that magnetic adhesion force can make the ribbon move toward and stay on the magnetic take-up roll. The tests indicated that the results measured complied with simulation ones. Moreover, the final design prototype test successfully satisfy the main objective of the project – to take up the ribbon – with a high success rate.     

数据中心交直流混合供电系统效率浅析

介绍了数据中心交直流混合供电系统方案产生的背景。针对目前认为交流直供承担所有负载效率最优化的观点,对交直流混合供电系统的效率进行了理论分析和试验验证,说明了交直流混合供电系统方案中系统效率的影响因素以及在现网机房中如何实现该方案的最佳效率点。作为简单的参考原则,在高压直流系统（HVDC）不休眠的情况下,在目前业界主流的产品配置下,推荐采用交流和高压直流系统（HVDC）均分负载的供电模式。     

从美国AHRI标准210/240中季节能效比的测试计算方法看房间空调器节能技术

本文从美国AHRI标准210/240中对房间空调器季节能效比(SEER)的定义以及测试试验、计算方法入手,阐述房间空调器提高季节能效比的若干方法与方向,在大力提倡节能降耗的新形式下,为提高现有中低能效房间空调器的季节能效比提供设计参考.     

风力发电机叶片变桨距偏离方式的受力分析

通过叶素理论及贝茨理论对两种风机叶片桨距角调节方法进行了对比,系统分析叶片桨距角偏离所引起的受力、边界层分离、攻角及桨距角等参数的变化,计算出叶片升力/阻力变化;通过求解流体边界层方程,揭示出叶片偏离最优桨距角之后产生的实际变化。得到下述结论:桨距角变大时,风机效率变化稳定但变化慢,桨距角调节范围较大;桨距角变小时,风机效率变化敏感,调整范围需要精密控制;该结论可为不同应用区域风机叶片参数调整方式的确定提供参考。     

长三角地区县域中小城市空间形态对碳排放效率影响研究

城市空间形态与碳排放效率存在密 切联系,探究两者间关系可以为县域中小城市 低碳发展提供指引,并为实现高质量发展提 供新参考。文章在大城市碳排放效率评价研 究的基础上结合县域中小城市特征,进行碳 排放效率评价指标选取及模型构建,通过建 立面板数据模型对2005—2020年间长三角 地区县域中小城市空间形态对碳排放效率影 响进行了实证研究,并分析了城市空间形态 对碳排放效率的影响机理。结果表明：城市 空间形态紧凑度、复杂度及破碎化程度与碳 排放效率密切相关;紧凑程度的提高对碳排 放经济效率具有促进作用,复杂程度和破碎 化程度的下降会对碳排放经济效率和碳排放 社会效率产生积极影响。总体而言,城市空间 形态主要通过影响交通碳排放进而对碳排 放效率产生影响,交通碳排放水平是长三角 地区县域中小城市碳排放经济效率和碳排放社会效率的首要影响因素。结合研究结论,本文提出强化结构性填充式开发以及调整空间组织 模式等策略,以期助力县域中小城市低碳发展。     

2~6 GHz紧凑型、高效率GaN MMIC功率放大器

基于0.25 μm SiC衬底的GaN高电子迁移率晶体管(HEMT)工艺,根据有源器件的G_max和输出功率密度,选择末级功率器件尺寸并确定其最优阻抗;采用三级放大器,其栅宽比为1:4:16,实现高功率增益和高效率;利用等Q匹配技术,把偏置电路融入匹配电路中,实现简单、低损耗和宽带阻抗变换;借助电磁场寄生参数提取技术实现紧凑型芯片版图,尺寸为2.8 mm×2.0 mm。测试结果表明,偏置条件漏极电压U_D=28 V、U_G=-2.2 V,在2~6 GHz频率范围内,功率放大器增益大于24 dB,饱和输出功率大于43 dBm,功率附加效率大于45%,可广泛应用于电子对抗和电子围栏等领域。