Photo‐excited Oxygen Reduction and Oxygen Evolution Reactions Enable a High‐Performance Zn–Air Battery

The storage of solar energy in battery systems is pivotal for a sustainable society, which faces many challenges. Herein, a Zn–air battery is constructed with two cathodes of poly(1,4‐di(2‐thienyl))benzene (PDTB) and TiO₂ grown on carbon papers to sandwich a Zn anode. The PDTB cathode is illuminated in a discharging process, in which photoelectrons are excited into the conduction band of PDTB to promote oxygen reduction reaction (ORR) and raise the output voltage. In a reverse process, holes in the valence band of the illuminated TiO₂ cathode are driven for the oxygen evolution reaction (OER) by an applied voltage. A record‐high discharge voltage of 1.90 V and an unprecedented low charge voltage of 0.59 V are achieved in the photo‐involved Zn–air battery, regardless of the equilibrium voltage. This work offers an innovative pathway for photo‐energy utilization in rechargeable batteries.     

阻尼对空爆荷载等效静载动力系数的影响

为考查阻尼参数对空爆荷载等效静载动力系数的影响,理论推导了空爆荷载下结构等效单自由体系弹塑性位移解及延性比解,设计并计算了阻尼比0.000 1～0.1、延性比1～4的20种典型工况的动力系数,并与现行抗爆设计规范动力系数公式结果进行了对比。结果表明:阻尼比小于0.000 1时可基本代表无阻尼状态,阻尼比0.01的动力系数比无阻尼的最大降低幅度为2.08%,数值差异很小,因此阻尼比为0.01以内时,可忽略阻尼对动力系数的影响;阻尼比0.05的动力系数比无阻尼的降低幅度约9.92%,数值差异较大,认为阻尼比0.05以上时将具有明显的经济效益;现行设计规范动力系数更适用于柔性结构体系,运用于刚性结构抗爆设计时,计算误差较大,对阻尼比较小的结构设计更不利。     

Real‐Time Monitoring of Transport of Chlorinated Hydrocarbons from Industrial Areas Using Open‐Path FTIR Spectrometry with COL1SB

Abstract

Open‐path Fourier transform infrared (FTIR) spectrometry was used to continuously monitor 11 chlorinated hydrocarbon species in the region connecting two different industrial complexes for 24 hr. The single‐beam spectra obtained from open‐path FTIR were analyzed by newly developed software named COL1SB, which generates site‐specific background spectra as well as path‐averaged water vapor concentrations in addition to performing regression analyses. The path‐averaged water vapor concentrations calculated by the COL1SB agreed very well with those measured by a thermo‐hygrometer. In addition, site‐specific background spectra were generated by accounting for chemical absorption of 50 chemical species. The accurate estimation of path‐averaged water vapor concentrations, as well as the usage of site‐specific background spectra, enables chlorinated hydrocarbons to be measured by open‐path FTIR spectrometry at the ppb level. Among 11 chlorinated hydrocarbons considered here, trichlorofluoromethane, carbon tetrachloride, trichloroethylene, and tetrachloroethylene were identified as major chlorinated hydrocarbons having concentrations above 1 ppb. Wind affected the temporal variations of these chlorinated hydrocarbons, indicating the importance of local transport. However, the effect of wind differed from one species to another because of different source characteristics.     

Solid Introduction to an ICP-Atomic Emission Spectrometer for the Analyses of Metals Contents of Air Filters

The direct introduction of solid samples (air filters) to the inductively coupled plasma source of an atomic emission spectrometer using a furnace atomizer has been studied. Conditions have been found for the analysis of elements which volatilize with varyling degrees of difficulty. Lead, copper and vandaium compounds retained on glass fibre filters from air pollution studies have been determined. The results are in good agreement with those obtained by means of established sample dissolution/atomic emision methods.     

Experimental and LES investigation of premixed methane/air flame propagating in a tube with a thin obstacle

In this paper, an experimental and numerical investigation of premixed methane/air flame dynamics in a closed combustion vessel with a thin obstacle is described. In the experiment, high-speed video photography and a pressure transducer are used to study the flame shape changes and pressure dynamics. In the numerical simulation, four sub-grid scale viscosity models and three sub-grid scale combustion models are evaluated for their individual prediction compared with the experimental data. High-speed photographs show that the flame propagation process can be divided into five stages: spherical flame, finger-shaped flame, jet flame, mushroom-shaped flame and bidirectional propagation flame. Compared with the other sub-grid scale viscosity models and sub-grid scale combustion models, the dynamic Smagorinsky–Lilly model and the power-law flame wrinkling model are better able to predict the flame behaviour, respectively. Thus, coupling the dynamic Smagorinsky–Lilly model and the power-law flame wrinkling model, the numerical results demonstrate that flame shape change is a purely hydrodynamic phenomenon, and the mushroom-shaped flame and bidirectional propagation flame are the result of flame–vortex interaction. In addition, the transition from “corrugated flamelets” to “thin reaction zones” is observed in the simulation.     

小型家用空调器除霜方式的探讨

提高低温制热量是小型家用空调器技术的一个难点,除霜带来的热量损失是低温制热量损失的一个重要方面。对小型家用空调器的除霜技术的发展进行了分析和总结,对小型家用空调器提出了一些新的除霜方式,对提高空调器的低温制热量、使用性能有重要意义。     

变频空调制冷系统流量调节性能分析和实验研究

通过实验分析不同膨胀阀开度和压缩机频率下系统性能。过热度在‘0’点及前后情况下,制冷系统性能及回油状况随膨胀阀开度调节,会出现较大变化。且在过热度为‘0’时系统制冷量和能效比最高。同时对不同频率下系统性能参数变化规律尤其是换热器效率影响进行分析。给出膨胀阀开度和压缩机变转速联合调节在系统性能最优状态下调节策略。     

用修正的RELIEF方法测量高速空气流瞬时速度的理论研究

修正了拉曼激发激光感应电子荧光（ＲａｍａｎＥｘｃｉａｔｉｏｎｐｕｌｓｅＬａｓｅｒ－ｉｎｄｕｃｅｄＥｌｅｃｔｒｏｎｉｃＦｌｕｏｒｅｓｃｅｎｃｅ简称ＲＥＬＩＥＦ）方法，以实现对亚音速和超音速空气流多点时速度的测量，测量精度优于２％。     

Sol-Gel Nanosized Semiconducting Titania-Based Powders for Thick-Film Gas Sensors

Pure, 5 at%, and 10 at% Ta- or Nb-doped TiO₂ nanosized powders were prepared by the sol-gel method. The powders heated to 400°C have the crystalline anatase structure. While the pure TiO₂ powder heated to 850°C has the rutile structure, the addition of Ta and Nb inhibited the anatase-to-rutile phase transformation at this temperature. Ta was soluble in the titania lattice up to the concentration of 10 at%, while the solubility of Nb was 5 at%. Thick films were fabricated with these powders by screen printing technology and then fired at 650°C and 850°C for 1 h. SEM observations showed that the anatase-to-rutile phase transformation induces a grain growth of about one order of magnitude for pure TiO₂. The addition of Ta and Nb is effective to keep the TiO₂ grain size at the nanometric level even at 850°C. Conductance measurements showed that a good gas response is observed only for the nanostructured titania-based films. The CO response of these materials is only slightly affected by humidity.     

一种新型的空气扰动探测方法

基于光折变材料的二波耦合特性提出了一种新型的空气扰动探测方法。空气中的微扰导致入射到光折变材料中两束光的光程差发生改变，干涉条纹随之发生变化。由于光折变体相位栅建立时间比较长，体相位栅不能及时跟随干涉条纹发生变化，导致干涉条纹与体相位栅间的相移将随空气扰动信息的变化而变化。相移角的改变将导致瞬态能量转移，输出两束光的能量在瞬态能量转移作用下将实现对空气扰动信息的光调制，并且这种调制过程是一种差分调制方式。在接收端采用电差分检测方法便可解调出空气扰动信息。这种利用光折变体相位栅的差分探测方法在未来的探测领域将有广泛的应用前景。