Study on two-stage concentration detection algorithm based on UV-DOAS: For mixed gas of NO and SO2

Nafion/TiO2 nanoparticle decorated thin film composite hollow fiber membrane for efficient removal of SO2 gas

CO2 and SO2 gases are utilized in various industrial applications and are subjects of environmental research. However, these gases are considered toxic and pose dangers at certain concentrations. Therefore, it is crucial to monitor and control the exposure to these gases in the environment to prevent reaching hazardous levels that could endanger both humans and the environment. A non-contact detection and monitoring system is essential to minimize the adverse effects of direct gas exposure. In this research, a non-contact detection system for CO2, SO2, and mixed gases was developed using optical imaging analysis generated by infrared cameras. The images were captured using the FLIR Vue Pro-R infrared camera, with infrared absorbing gas sourced from a 50-watt tungsten lamp. Visual identification of these gases through optical imaging is challenging; however, this study successfully identified these gases using a Convolutional Neural Network (CNN). The CNN architecture used in this study is DenseNet (Densely Connected Convolutional Networks), comprising 169 convolution layers. The CNN model was trained and tested on experimental optical imaging data, categorized into three classes: CO2, SO2, and a mixture of gases. A total of 1030 optical imaging data points were utilized for training. Training was conducted using the AdamW optimization function over 28 epochs. The evaluation of results yielded accuracy, precision, recall, and F1-score metrics. The novelty of this study lies in the successful identification of CO2, SO2, and their mixture by the CNN model with an accuracy of 85%. Precision, recall, and F1-score values are all 0.85. These results indicate that the CNN model effectively distinguishes optical imaging of each gas (CO2, SO2, and their mixture) consistently and accurately. Consequently, it can be concluded that the CNN model performs well in distinguishing between these gases in optical imaging analysis.

This paper proposes an improved target detection algorithm, SDE-YOLO, based on the YOLOv5s framework, to address the low detection accuracy, misdetection, and leakage in blood cell detection caused by existing single-stage and two-stage detection algorithms. Initially, the Swin Transformer is integrated into the back-end of the backbone to extract the features in a better way. Then, the 32 × 32 network layer in the path-aggregation network (PANet) is removed to decrease the number of parameters in the network while increasing its accuracy in detecting small targets. Moreover, PANet substitutes traditional convolution with depth-separable convolution to accurately recognize small targets while maintaining a fast speed. Finally, replacing the complete intersection over union (CIOU) loss function with the Euclidean intersection over union (EIOU) loss function can help address the imbalance of positive and negative samples and speed up the convergence rate. The SDE-YOLO algorithm achieves a mAP of 99.5%, 95.3%, and 93.3% on the BCCD blood cell dataset for white blood cells, red blood cells, and platelets, respectively, which is an improvement over other single-stage and two-stage algorithms such as SSD, YOLOv4, and YOLOv5s. The experiment yields excellent results, and the algorithm detects blood cells very well. The SDE-YOLO algorithm also has advantages in accuracy and real-time blood cell detection performance compared to the YOLOv7 and YOLOv8 technologies.

It is well known that the fatigue strength of steels is decreased by oxygen and/or humidity in the atmospheres. Only few reports have been published, however, on the effect of impurities such as SO2 gas on the fatigue strength of steels. In order to study the effect of SO2 gas on fatigue strengths of steels, rotating bending fatigue tests of a mild steel, a 60 kg/mm2 and an 80 kg/mm2 high strength steels and an 18-8 stainless steel have been corned out in various atmospheres. The employed atmospheres are air, humidified a'r, dry SO2 gas, mixed gas of dry SO2 and humidified air, mixed gas of dry H2S and humidified air, H2O, and H2SO4.On the fatigue strength of the mild steel the influence of dry SO2 gas is not recognized, but the influence of mixed gas of dry SO2 gas and humidified air is detected. The degree of the influence, however, is almost the same as that in humidified air. Therefore the influence of SO2 gas on fatigue strength of the mild steel seems to be little, but some influences of SO2 gas can be surmised from the characteristic aspect of fractured surfaces. On the 60 kg/mm2 and 80 kg/mm2 high strength steels and the 18-8 stainless steel the influence of SO2 gas is not observed. For all the steels tested in this experiment, the influence of H2SO4 is very conspicuous.

Dry scrubbing of gaseous HCl and SO2 with hydrated lime in entrained mixing reactor

Reaction of Portland cement clinker with gaseous SO2 to form alite-ye'elimite clinker

Experimental analysis of the performance of a multisensor two-stage fire detection and water discharge algorithm

By using ultraviolet absorption spectroscopy detection technique,the real-time monitoring for the concentrations of SO2 and H2S mixed gas was realized. Deuterium lamp was used as a light source,and MAYA2000 Pro spectrometer served as spectrograph in the experiment. Based on BeerLambert law and absorption spectrum,the formula of SO2 concentration was deduced by choosing very close two points in the absorption spectrum,which could ignore the interference of the scattering and absorption from other gas. The absorption spectrum of H2 S gas can be achieved by subtracting the corresponding absorption spectrum of SO2 gas from mixed gas spectrum. At the normal temperature and pressure,the concentration of H2 S could be obtained from the absorption peak of H2 S absorption spectrum. The measuring accuracy of mixed gas is about 1 × 10-6( 1 ppm). So,our work realizes the real-time monitoring for SO2 and H2S in mixed gas.

Effects of X (X = H2S, SO2 and N2O) mole fractions on adsorption behavior and phase equilibrium properties of CO2 + X mixed gas hydrate

The presence of HCl and SO2 gas imposes limitations on syngas utilization obtained from household waste in a wide range of applications. The hydrotalcite-like compounds (HTLs) have been proved that could remove HCl efficiency. However, the research on impact of synthesis conditions of HTLs and SO2 on HCl removal was limited. In this study, a range of Ca–Mg–Al mixed oxide sorbents was synthesized by calcining HTLs, with variations in crystallization temperature, solution pH, and the Ca/Mg molar ratio. These sorbents were examined for their effectiveness in removing HCl at medium–high temperatures under diverse conditions. The adsorption performance of selected sorbents for the removal of HCl, SO2, and HCl-SO2 mixed gas at temperature of 350 °C, 450 °C, and 550 °C, respectively, was evaluated using thermogravimetric analysis (TGA). It was observed that the HTL synthesis parameters significantly influenced the HCl adsorption capacity of Ca–Mg–Al mixed oxides. Notably, HTLs synthesized at 60 °C, a solution pH of 10–11, and a Ca/Mg ratio of 4 exhibited superior crystallinity and optimal adsorption characteristics. For individual HCl and SO2 removal, temperature had a minor effect on HCl adsorption but significantly impacted SO2 adsorption rates. At temperatures above 550 °C, SO2 removal efficiency substantially decreased. When exposed to a mixed gas, the Ca–Mg–Al mixed oxides could efficiently remove both HCl and SO2 at temperatures below 550 °C, with HCl dominating the adsorption process at higher temperatures. This dual-action capability is attributed to several mechanisms through which HTL sorbents interacted with HCl, including pore filling, ion exchange, and cation exchange. Initially, HCl absorbed onto specific sites created by water and CO2 removal due to the surface’s polarity. Subsequently, HCl reacted with CaCO3 and CaO formed during HTL decomposition.Graphical abstract

In order to develop an atomosphere assessment method, we investigated the compound corrosive action of mixed gases by analyzing the products of corrosion of exposed metals and alloys, using an electron probe microanalyzer. Test pieces were exposed to mixed gases : H2S or SO2 (10 ppm) as a background plus HCl, HNO3 (1 ppm respectively) or NH3 (100 ppm) under 90% relative humidity. Test piece metals and alloys were copper, five copper alloys, silver, aluminum, iron and 52 alloy, which are most used for electronic instruments.In H2S background gas the results are as follows:(1) When HCl gas is added, corrosion of nickel silver, cupro-nickel, iron, and 52 alloy is accelerated, and corrosion of beryllium copper, phosphor bronze and silver is suppressed.(2) When HNO3 gas is added, corrosion of all the metals and alloys is suppressed, but after corrosion once begins, corrosion of nickel silver and cupro-nickel is accelerated.(3) When NH3 gas is added, corrosion of brass, silver and 52 alloy is accelerated, and corrosion of nickel silver, and cupro-nickel is suppressed.In SO2 background gas the results are as follows:(1) When HCl gas is added, corrosion of iron is accelerated and corrosion of other metals and alloys is suppressed.(2) When HNO3 gas is added, corrosion of all the metals and alloys is suppressed.(3) When NH3 gas is added, SO2 gas is exhausted to produce ammonium compound, and no corrosive reaction occurs.

The oxidation of nickel sulfide whose atomic fraction of sulfur,x s, is 0.40 to 0.44 was studied in a mixed O2-N2 gas stream at 923, 973, and 1023 K. The oxygen partial pressure was maintained at 2.0 x 104 Pa. In the oxidation of nickel sulfide ofx s = 0.40 and 0.41, a dense NiO layer was formed on the sulfide surface without the evolution of SO2 gas, because of the low sulfur activity. Diffusion of nickel within the inner sulfide core toward the surface controlled the oxidation rate during the first one minute of oxidation. Subsequently, the oxidation rate was controlled by the diffusion of nickel through the formed NiO layer. In the oxidation of nickel sulfide ofx s = 0.44 at 973 and 1023 K, the reaction proceeded irregularly to the interior of the sulfide core with the evolution of SO2 gas, and a porous oxide layer was formed, due to the high sulfur activity of nickel sulfide. For the same reason, this oxidation was also accompanied by the dissociation of nickel sulfide. Under the experimental conditions ofx s = 0.42, 1023 K and xs = 0.44,923 K, the oxidation started with weight increase and without the evolution of SO2 gas, and in the subsequent stage the weight decreased and SO2 gas was evolved.

A MIMO system (multiple antennas at the transmitter and receiver) is capable of very high theoretical capacities. Foschini et al. proposed V-BLAST (Vertical-Bell Lab Layered Space-Time) code with a detection algorithm based on linear combination nulling and successive symbol cancellation. However this conventional detection algorithm requires time to execute both these computational bottlenecks. The time delay will be enhanced if the number of transmit antennas increases. In order to avoid this obstacle, parallel symbol cancellation (PSC) was proposed. But the performance is degraded. In this paper, we propose a two-stage detection algorithm derived from the combination of SSC and PSC to improve the BER performance. The proposed scheme is applied to zero-forcing (ZF) and minimum mean square error (MMSE) criteria. We also perform simulation to verify the analysis.

Separation performance of PEBAX/PEI hollow fiber composite membrane for SO2/CO2/N2 mixed gas

Two-stage neural algorithm for defect detection and characterization uses an active thermography