Energy-Harvesting Characteristics of a Dual-Mode Magnetic Suspension for Vehicles: Analysis and Experimental Verification

The advantages of the proposed dual-mode magnetic suspension are it having a high level of safety and a compact structure compared with the previous studies. However, the structure parameters can affect the energy harvesting of the suspension system. Therefore, this paper aims to analyze the energy-harvesting characteristics of the proposed dual-mode magnetic suspension. Firstly, the structure and working principle of the proposed suspension are introduced. Then, the influences of the various parameters for the actuator on the energy regeneration characteristics are analyzed by the finite element method, such as the magnetic ring, the fixed plug thickness, the heat dissipation, and the air gap, and the actuator parameters are defined by the orthogonal analysis method. Furthermore, the numerical results of the energy harvesting are calculated. Finally, the vibration experimental setup is manufactured, and the simulation analysis is verified by the experiment. The results demonstrate that the excitation amplitude is 3.1 mm, the frequency is 18 Hz, and the maximum induced EMF is 8.8 V. Additionally, compared with passive suspension, the energy harvesting of the proposed suspension has been verified in the laboratory, which lays the foundation for the design and analysis of the dual-mode magnetic suspension in a real vehicle

Measurement report: quantifying source contribution of fossil fuels and biomass-burning black carbon aerosol in the southeastern margin of the Tibetan Plateau

Anthropogenic emissions of black carbon (BC) aerosol are transported from Southeast Asia to the southwestern Tibetan Plateau (TP) during the pre-monsoon; however, the quantities of BC from different anthropogenic sources and the transport mechanisms are still not well constrained because there have been no high-time-resolution BC source apportionments. Intensive measurements were taken in a transport channel for pollutants from Southeast Asia to the southeastern margin of the TP during the premonsoon to investigate the influences of fossil fuels and biomass burning on BC. A receptor model that coupled multi-wavelength absorption with aerosol species concentrations was used to retrieve site-specific Angstrom exponents (AAEs) and mass absorption cross sections (MACS) for BC. An "aethalometer model" that used those values showed that biomass burning had a larger contribution to BC mass than fossil fuels (BCbiomass = 57 % versus BCfossil = 43 %). The potential source contribution function indicated that BCbiomass was transported to the site from northeastern India and northern Burma. The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) indicated that 40 % of BCbiomass originated from Southeast Asia, while the high BCfossil was transported from the southwest of the sampling site. A radiative transfer model indicated that the average atmospheric direct radiative effect (DRE) of BC was +4.6 +/- 2.4 W m(-2), with +2.5 +/- 1.8 W m(-2) from BCbiomass and +2.1 +/- 0.9 W m(-2 )from BCfossil. The DRE of BCbiomass and BCfossil produced heating rates of 0.07 +/- 0.05 and 0.06 +/- 0.02 K d(-1), respectively. This study provides insights into sources of BC over a transport channel to the southeastern TP and the influence of the cross-border transportation of biomass-burning emissions from Southeast Asia during the pre-monsoon

Impacts of primary emissions and secondary aerosol formation on air pollution in an urban area of China during the COVID-19 lockdown

Restrictions on human activities were implemented in China to cope with the outbreak of the Coronavirus Disease 2019 (COVID-19), providing an opportunity to investigate the impacts of anthropogenic emissions on air quality. Intensive real-time measurements were made to compare primary emissions and secondary aerosol formation in Xi?an, China before and during the COVID-19 lockdown. Decreases in mass concentrations of particulate matter (PM) and its components were observed during the lockdown with reductions of 32-51%. The dominant contributor of PM was organic aerosol (OA), and results of a hybrid environmental receptor model indicated OA was composed of four primary OA (POA) factors (hydrocarbon-like OA (HOA), cooking OA (COA), biomass burning OA (BBOA), and coal combustion OA (CCOA)) and two oxygenated OA (OOA) factors (less oxidized OOA (LO-OOA) and more-oxidized OOA (MO-OOA)). The mass concentrations of OA factors decreased from before to during the lockdown over a range of 17% to 58%, and they were affected by control measures and secondary processes. Correlations of secondary aerosols/Delta CO with Ox (NO2 + O-3) and aerosol liquid water content indicated that photochemical oxidation had a greater effect on the formation of nitrate and two OOAs than sulfate; however, aqueous-phase reaction presented a more complex effect on secondary aerosols formation at different relative humidity condition. The formation efficiencies of secondary aerosols were enhanced during the lockdown as the increase of atmospheric oxidation capacity. Analyses of pollution episodes highlighted the importance of OA, especially the LO-OOA, for air pollution during the lockdown

Chemical composition and sources of submicron aerosols in winter at a regional site in Beijing-Tianjin-Hebei region: Implications for the Joint Action Plan

The Ministry of Environmental Protection released a joint Action Plan for Control of Air Pollution (Hereafter, joint Action Plan, JAP), to reduce PM2.5 concentrations in the Beijing-Tianjin-Hebei region (13TH) during the winter of 2017. To investigate the effectiveness of the controls, we deployed an aerosol chemical speciation monitor and collected filter samples at Xianghe, a representative site for the BTH, to characterize the aerosol composition during the implementation of the JAP. Those results were compared with earlier data obtained from a literature survey and reanalysis of studies in the BTH. During several pollution episodes in the control period, the major aerosol types changed relative to the earlier studies from sulfate, oxygenated organic aerosol, and coal combustion organic aerosol to nitrate and biomass burning organic aerosol. The dominant secondary inorganic aerosol species during the JAP changed from sulfate to nitrate, and the main source for primary organic aerosol switched from coal combustion to biomass burning. These changes can be explained by the fact that the JAP controls targeted coal combustion and SO2 but not biomass burning or NOx emissions. Our evaluation of the control measures provides a scientific basis for developing new policies in the future. (C) 2020 Elsevier B.V. All rights reserved

Zeolitic Imidazolate Framework Film Derived CoFe‐N‐C Nanofoams for Reliable Zn‐air Batteries

Abstract The design of the efficient, flexible air electrode for enhancing the Zn‐air batteries (ZABs) performance is vital in developing a new portable rechargeable power supply. Emerging research indicates that non‐precious metal materials have promising activity for oxygen reduction/evolution in alkaline conditions while constructing a high‐performance and reliable electrode is still a big challenge at the present stage. In this work, a bimetal doped zeolitic imidazolate framework (ZIF) film is synthesized by fast current‐driven synthesis (FCDS) on a thin carbon nanotube film (CNTF). After carbonization at 950 °C, CoFe‐N‐C nanofoam formed on the CNTF, resulting in binder‐free, flexible electrodes. It exhibits excellent activity and stability toward oxygen reduction and evolution. The CoFe‐N‐C/CNTF‐based liquid‐state ZAB shows an output power density of 294 mW cm−2. When applied in solid‐state ZAB, the flexible battery shows high power density and excellent cycling stability

Vehicle Stability Analysis under Extreme Operating Conditions Based on LQR Control

Under extreme working conditions such as high-speed driving on roads with a large road surface unevenness coefficient, turning on a road with a low road surface adhesion coefficient, and emergency acceleration and braking, a vehicle’s stability deteriorates sharply and reduces ride comfort. There is extensive existing research on vehicle active suspension control, trajectory tracking, and control methods. However, most of these studies focus on conventional operating conditions, while vehicle stability analysis under extreme operating conditions is much less studied. In order to improve the stability of the whole vehicle under extreme operating conditions, this paper investigates the stability of a vehicle under extreme operating conditions based on linear quadratic regulator (LQR) control. First, a seven degrees of freedom (7-DOF) dynamics model of the whole vehicle is established based on the use of electromagnetic active suspension, and then an LQR controller of the electromagnetic active suspension is designed. A joint simulation platform incorporating MATLAB and CarSim was built, and the CarSim model is verified by real vehicle tests. Finally, the stability of the vehicle under four different ultimate operating conditions was analyzed. The simulation results show that the root mean square (RMS) values of body droop acceleration and pitch angle acceleration are improved by 57.48% and 28.81%, respectively, under high-speed driving conditions on Class C roads. Under the double-shift condition with a low adhesion coefficient, the RMS values of body droop acceleration, pitch acceleration, and roll angle acceleration are improved by 58.25%, 55.41%, and 31.39%, respectively. These results indicate that electromagnetic active suspension can significantly improve vehicle stability and reduce driving risk under extreme working conditions when combined with an LQR controller

Chemical characteristics and sources of nitrogen-containing organic compounds at a regional site in the North China Plain during the transition period of autumn and winter

Organic nitrogen constitutes a significant fraction of the nitrogen budget in particulate matter (PM). However, the composition and sources of nitrogen-containing organic compounds (NOCs) in PM remain unclear currently in North China Plain (NCP), China. Rare local or regional studies on NOCs were conducted. In this study, ambient fine particles (PM2.5) were collected in Xianghe, a regional background site in NCP, from 26 October to 26 December 2017. The insights from this study include NOC molecule identification, concentration level, and NOC sources and origins. Specifically, we have identified and quantified >90 NOC species, with urea being the most abundant, accounting for 39.7 +/- 4.7% of the total NOC followed by free amino acids (FAAs; 21.9 +/- 1.5%), cyclic NOCs (15.3 +/- 4.5%), amines (14.8 +/- 1.5%), alkyl amides (5.8 +/- 0.5%), isocyanates (1.7 +/- 0.2%), and nitriles (1.1 +/- 0.2%). The time series of FAAs was well correlated (r = 0.51-0.68, p < 0.01) with the organic marker of levoglucosan and was moderately correlated with O-x (r = 0.29-0.41, p < 0.01), suggesting biomass burning and secondary formation were important FAAs sources. We also show that amines can be oxidized and/or reacted by aqueous-phase processing to form secondary aerosols, which are further enhanced by the involvement of iron in the catalytic process. Using the receptor model of positive matrix factorization (PMF), six factors were identified including coal combustion, crustal sources, biomass burning, industry-related sources, traffic emissions, and secondary aerosols. Source apportionment of NOC shows biomass burning was the dominant factor, accounting for 31.8% of the total NOCs. This study provides a unique dataset of NOCs at this regional background site in the NCP, with the insights of NOC chemical composition and sources gained in this study being important for future NOC modeling as well as NOC health effects studies