Traffic congestion detection based on vehicle detection and tracking algorithms is one of the key technologies for intelligent transportation systems. However, in expressway surveillance scenarios, small vehicle size and vehicle occlusion present severe challenges for this method, including low vehicle detection accuracy and low traffic congestion detection accuracy. To address these challenges, this paper proposes an improved version of the CrowdDet algorithm by introducing the Involution operator and bi-directional feature pyramid network (BiFPN) module, which is called IBCDet. The proposed IBCDet module can achieve higher vehicle detection accuracy in expressway surveillance scenarios by enabling long-distance information interaction and multi-scale feature fusion. Additionally, a vehicle-tracking algorithm based on IBCDet is designed to calculate the running speed of vehicles, and it uses the average running speed to achieve traffic congestion detection according to the Chinese expressway level of serviceability (LoS) criteria. Adequate experiments are conducted on both the self-built Nanjing Raoyue expressway monitoring video dataset (NJRY) and the public dataset UA-DETRAC. The experimental results demonstrate that the proposed IBCDet outperforms the commonly used object detection algorithms in both vehicle detection accuracy and traffic congestion detection accuracy.
Silica supported sulfuric acid (SSA) has been demonstrated to be capable of effectively removing phenyl VOCs through the reaction-type adsorption mechanism. The effects of the solvent (water, ethyl acetate) used to impregnate silica gel with H2SO4 solution in order to prepare SSA adsorbents have been studied. As-prepared two series SSA(E)-x and SSA(W)-x materials (x = 1, 2, 3, 4) were characterized by TG, SEM/EDS and N2 adsorption/desorption techniques, and their breakthrough adsorption performances were evaluated from experimental and theoretical aspects. The results showed that the H2SO4 loading amounts were 2.8, 4.0, 4.8 and 5.6 mmol g−1 respectively for both SSA(E)-x and SSA(W)-x when x equaled 1, 2, 3, 4. Among them, SSA(E)-4 was found to have a higher proportion of the C-state H2SO4 than SSA(W)-4. Both SSA(E)-x and SSA(W)-x exhibited significant removal capacity of gaseous o-xylene. The reactive temperature regions were determined to be 120–170 °C for SSA(E)-4 and 120–160 °C for SSA(W)-4 with a common optimum point of 160 °C. Both SSA(E)-x and SSA(W)-x adsorbents exhibited excellent recyclability and reuse performance. Further, the series SSA(E)-x materials outperformed the series SSA(W)-x on all adsorption performance metrics, suggesting that ethyl acetate is a preferred solvent for preparing the SSA materials in phenyl VOCs removal application.
To establish a novel approach for VOCs resource utilization, coupled o-xylene oxidation and hematite reduction was investigated in this study in a high-temperature gas-solid reactor in the temperature range 300–700 °C. As the o-xylene-containing inert gas (N2) stream traveled through the hematite particle bed, its reaction behavior was determined in programmed heating and constant temperature modes. Consequently, the effect of bed temperature, flow rate and o-xylene inlet concentration on both o-xylene removal performance and degree of hematite reduction was studied. The raw hematite and solid products were analyzed by TGA, XRF, XRD and SEM-EDS. The results showed that a temperature above 300 °C was required to completely eliminate o-xylene by hematite, and both o-xylene removal capacity and degree of hematite reduction at 5% breakthrough points enhanced on increasing the temperature and decreasing the flow rate. The increment in temperature from 300 °C to 700 °C led to a gradual reduction of Fe2O3 to Fe3O4, FeO and metallic iron. Thus, this study provides a novel, economic and promising technology for treating the VOC pollutants.
Efficient removal of cumene from gaseous streams and recovery of its derivatives was accomplished using a MCM-41-supported sulfuric acid (SSA/MCM-41) adsorbent. The results indicated that the removal performance of the SSA/MCM-41 for cumene was significantly influenced by the process conditions such as bed temperature, inlet concentration, bed height, and flow rate. The dose–response model could perfectly describe the collected breakthrough adsorption data. The SSA/MCM-41 adsorbent exhibited a reactive temperature region of 120–170 °C, in which the cumene removal ratios (Xc) were greater than 97%. Rising the bed height or reducing the flow rate enhanced the theoretical adsorption performance metrics, such as theoretical breakthrough time (tB,th) and theoretical breakthrough adsorption capacity (QB,th), whereas increasing the inlet concentration resulted in tB,th shortening and QB,th rising. As demonstrated in this paper, the highest tB,th and QB,th were 69.60 min and 324.50 mg g−1, respectively. Meanwhile, the spent SSA/MCM-41 could be desorbed and regenerated for cyclic reuse. Moreover, two recoverable adsorbed products, 4-isopropylbenzenesulfonic acid and 4, 4′-sulfonyl bis(isopropyl-benzene), were successfully separated and identified using FTIR and 1H/13C NMR characterization. Accordingly, the relevance of a reactive adsorption mechanism was confirmed. This study suggests that the SSA/MCM-41 has remarkable potential for application as an adsorbent for the resource treatment of cumene pollutants.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.