Search

In challenging night-time settings, drivers often struggle to accurately discern nearby vehicles, which can lead to traffic incidents due to complex lighting conditions and the issues of dim visibility, blurring, and occlusion of vehicles. To address this issue, this study introduces an advanced method that utilizes an enhanced YOLOv5 algorithm designed to improve the detection of vehicles during night driving and ensure detection accuracy in low-light environments. The method integrates SKAttention into the network's Backbone layer to address overlapping and redundant information within the model. This integration is achieved by generating multiple pathways with varying convolutional kernel sizes, which correspond to the different sensory field sizes of neurons, thus enhancing information processing efficiency. Additionally, the original up-sampling operator of the model is replaced with the Content-Aware Feature Reorganization (CARAFE), which leverages underlying content information to predict the reorganization kernel and reassemble predefined neighborhood features, preserving the quality of feature maps post-zooming. The incorporation of SIOU also significantly enhances the model's ability to pinpoint defect locations with greater accuracy, leading to improvements in both training speed and inference accuracy. Experimental results demonstrate that the optimized model, dubbed KSC-YOLOv5, surpasses the baseline YOLOv5 model, showing a mean average precision (mAP) increase of 2 percentage points to 91.2%. Furthermore, when compared with other iterations of the YOLO algorithm, KSC-YOLOv5 exhibits superior performance in terms of average detection accuracy. This refined model effectively navigates the challenges posed by inadequate lighting and vehicle blurring in nocturnal environments, achieving precise vehicle detection. [ABSTRACT FROM AUTHOR]

The low power consumption of the near-critical compressor is the key factor for the high efficiency of supercritical CO2 Brayton cycle. In the numerical simulation of the compressor, the rapid changes in the thermophysical properties of the CO2 near the critical point make it difficult to capture the condensation phenomenon. This paper investigates the influence of fluid physical properties on the condensation phenomenon. Firstly, the differences in the physical properties of CO2 in the SRK EOS (equation of state), PR EOS, and SW EOS are compared. Then, the simulation of nozzles and compressors were carried out and discussed. Results show that the condensation positions predicted by the three EOSs are basically the same. Compared with SW EOS, the disparities between the maximum condensation mass fraction predicted by the PR and SRK EOSs is 5.7% and 11.5%, and that of total pressure ratio is 0.3% and 3.8%, respectively. The results show that PR EOS can be considered for numerical simulation in engineering practice. Since its physical property calculation results are closer to the actual physical properties while the physical properties change more gently, it has considerable accuracy and numerical stability. [ABSTRACT FROM AUTHOR]

As the bottom cycle of gas turbine waste heat utilization, the S-CO2 cycle can enhance the power output capacity of the system. Based on the energy analysis of the recompression cycle and the partial cooling cycle for gas turbine waste heat utilization, the two cycles are improved from the matching of heat exchange flow of regenerator and heater in this paper. Under the same parameters, compared with the cycle before improvement, increase in heat source utilization rate and net power output of improved cycles is 45.69% and 39.31%, 43.54 MW and 35.43 MW, and the power consumption cost is decreased by 0.6106 $/kWh and 0.6289 $/kWh. However, as part of heat recovery inside the system is replaced by the heat of the heat source, the thermal efficiency is decreased by 10.43% and 8.7%, respectively. Variable parameter study is conducted on the two improved cycles to analyze the cycle characteristics from the perspective of energy, exergy, and economy (3E). The results showed that the improved recompression cycle has a high thermal power conversion capacity, higher system thermal efficiency and exergy efficiency and lower power generation cost, while the improved partial cooling cycle has higher waste heat utilization potential. However, the area of heat exchangers in both cycles tends to increase, which is not conducive to the compactness of the system. [ABSTRACT FROM AUTHOR]

The objective of this paper is to understand the benefits that one can achieve for large-scale supercritical CO2 (S-CO2) coal-fired power plants. The aspects of energy environment and economy of 1000 MW S-CO2 coal-fired power generation system and 1000 MW ultra-supercritical (USC) water-steam Rankine cycle coal-fired power generation system are analyzed and compared at the similar main vapor parameters, by adopting the neural network genetic algorithm and life cycle assessment (LCA) methodology. Multi-objective optimization of the 1000 MW S-CO2 coal-fired power generation system is further carried out. The power generation efficiency, environmental impact load, and investment recovery period are adopted as the objective functions. The main vapor parameters of temperature and pressure are set as the decision variables. The results are concluded as follows. First, the total energy consumption of the S-CO2 coal-fired power generation system is 10.48 MJ/kWh and the energy payback ratio is 34.37%. The performance is superior to the USC coal-fired power generation system. Second, the resource depletion index of the S-CO2 coal-fired power generation system is 4.38 µPRchina,90, which is lower than that of the USC coal-fired power generation system, and the resource consumption is less. Third, the environmental impact load of the S-CO2 coal-fired power generation system is 0.742 mPEchina,90, which is less than that of the USC coal-fired power generation system, 0.783 mPEchina,90. Among all environmental impact types, human toxicity potential HTP and global warming potential GWP account for the most environmental impact. Finally, the investment cost of the S-CO2 coal-fired power generation system is generally less than that of the USC coal-fired power generation system because the cost of the S-CO2 turbine is only half of the cost of the steam turbine. The optimal turbine inlet temperature T5 becomes smaller, and the optimal turbine inlet pressure is unchanged at 622.082°C/30 MPa. [ABSTRACT FROM AUTHOR]

The recycling and utilization of feather waste from animal husbandry and straw from agriculture is a worldwide problem. In this study, keratin was extracted from waste feathers and used to modify urea‐formaldehyde (UF) adhesive to obtain biodegradable adhesive for making straw flowerpots with high performance. The results showed that keratin could reduce free formaldehyde and improve the thermal stability of UF. Furthermore, the mechanical properties of the flowerpot with keratin were greatly improved. The observed performance enhancements were attributed to the excellent adhesiveness of the bonding interface. In addition, the addition of keratin makes the flowerpot more hydrophilic and provides a better source of nutrients for microbes to grow and reproduce on the surface of the flowerpot, which is more conducive to the biodegradation of flowerpots after they are discarded. Our experiment suggests the great potential in terms of profitability and environmental protection by flowerpots prepared by fermented straw fiber and keratin‐modified UF. [ABSTRACT FROM AUTHOR]

The objective of this paper is to provide the optimal choice of single-reheating or double-reheating when considering residual flue gas heat in S-CO2 coal fired power system. The cascade utilization of flue gas energy includes three temperature levels, with high and low temperature ranges of flue gas heat extracted by S-CO2 cycle and air preheater, respectively. Two methods are proposed to absorb residual flue gas heat Qre in middle temperature range. Both methods shall decrease CO2 temperature entering the boiler T4 and increase secondary air temperature Tsec air, whose maximum value is deduced based on energy conservation in air preheater. The system is analyzed incorporating thermodynamics, boiler pressure drop and energy distribution. It is shown that at a given main vapor temperature T5, the main vapor pressure P5 can be adjusted to a value so that Qre is completely eliminated, which is called the main vapor pressure adjustment method. For this method, single-reheating is only available for higher main vapor temperatures. The power generation efficiency for single-reheating is obviously higher than double-reheating. If residual flue gas heat does exist, a flue gas heater FGC is integrated with S-CO2 cycle, which is called the FGC method. Both single-reheating and double-reheating share similar power generation efficiency, but single-reheating creates less residual flue gas heat. We conclude that single-reheating is preferable, and the pressure adjustment method achieves obviously higher power generation efficiency than the FGC method. [ABSTRACT FROM AUTHOR]

In this study, benzylated bamboo flour (BBF) was synthesized using benzyl chloride under mild conditions. This material can be added to medium density polyethylene (MDPE) as a reinforcing filler material. The crystal structure and properties of the BBF and corresponding BBF/MDPE panels were investigated by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, mechanical tests and surface hydrophobicity measurements, and the obtained results are in good agreement. According to the scanning electron microscopy and X-ray diffraction investigations, the crystal structure of the bamboo material disappeared after the addition of benzyl chloride. The Fourier transform infrared spectroscopy analysis provided further evidence for the successful benzylation. The intensity of the bands attributed to the O-H stretching or deformation vibrations decreased, and the intensity of the bands attributed to the C = O and C-O bonds in the benzyl group increased, which was confirmed by the X-ray spectroscopy analysis. The volume fraction of the dispersed phase increased dramatically, and the interfacial fusion between the BBF particles and the MDPE matrix improved. The tensile strength and flexural strength of the prepared BBF/MDPE panels were up to 24.21% and 26.73% higher, respectively, compared with panels fabricated from unmodified bamboo flour. Furthermore, the surface hydrophobicity was found to be higher, which confirmed the good interface fusion. The strengthening mechanism is discussed in this paper, and the overall results suggest that BBF is a promising candidate material for the substitution of traditional wood fibers and unmodified bamboo flour in wood plastic composites. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The hydrolytes soy protein isolates (HSPI)-modified urea–formaldehyde (UF) resins were synthesized via copolymerization process. The best bonding strength is 1.50 MPa and improves 51.5% compared with pure UF. In addition, the formaldehyde emission decreased. The effect of (HSPI) on the biodegradable (UF) resins was investigated. Biodegradation was evaluated by composting under controlled conditions in accordance with ISO 14855. The faster degradation rate was obtained when lower hydrolysis degree of HSPI was added into the system. Characterization of the resulting samples was performed by attenuated total reflection Fourier transform infrared spectroscopy, thermo-gravimetric analysis, XRD, scanning electron microscopy, and AFM. The results showed that no evidence of biodegradation was found for UF resins. The UF modified with lower hydrolysis degree of hydrolytes soy protein isolates (HSPI) resulted in a faster degradation rate. The HSPI in the network of modified UF degraded first, which resulted in the broken of the network of HSPI-modified UF resins. The thermal stability of degraded resins was found to be enhanced as the mineralization time increased. Not only the surface of the sample was degraded, but also the crystalline regions of the samples were also decomposed. The degradation on the modified UF surface occurs mainly via the formation of holes. The roughness of the degraded surfaces of modified UF resins increases with the hydrolysis degree of HSPI decreases. The presence of HSPI has driven the degradation of urea–formaldehyde. The modified resins used as adhesives in biodegradable seedling container can be seen as a controlled release source of nitrogen fertilizer. [ABSTRACT FROM PUBLISHER]

The hydrolyzed soy protein isolate (HSPI) was used to partially substitute urea to synthesis modified urea–formaldehyde (UF) adhesives via copolymerization process, in order to reduce the dependency on petroleum-based chemicals and mitigate possible environmental pollution. The soy protein isolate (SPI), HSPI, and modified UF adhesives were characterized by attenuated total reflection Fourier transform infrared spectroscopy,1H nuclear magnetic resonance (1H NMR), and thermo-gravimetric analysis (TGA). The bonding strength, adhesive properties, biodegradability, and micrographs of the UF and HSPI-modified UF after degradation were also measured. The results show that the SPI native structure is unfolded during the treatment with sodium hydroxide. The thermal stability of HSPI is better than SPI. HSPI can incorporate into the structure of cured UF adhesives with three different feeding methods. And the best bonding strength of modified UF adhesives is 1.31 MPa when HSPI is added at the first step. The formaldehyde emission of modified UF adhesives is lower compared with UF. The earlier the HSPI is added, the better the properties for modified UF adhesives can be obtained. The degradation rate of modified UF adhesives improved nearly two times compared to the UF after six months of degradation in biologically active soil. There are microorganisms adhering to the surface of modified UF from the SEM micrographs. [ABSTRACT FROM AUTHOR]

ABSTRACT The hydrolyzed soy protein isolate (HSPI) with different hydrolysis degree was applied to modify urea-formaldehyde resins (UF) via copolymerization process. The properties of HSPI were characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and TGA. The results show that HSPI with different hydrolysis degree is obtained. 1H NMR and ATR-FTIR spectra indicate that HSPI with different hydrolysis degree can incorporate into the structure of cured and uncured UF. The UF modified with higher hydrolysis degree of HSPI possess more stable units and contribute to the lower exothermic peak temperature in DSC curves. The bonding strength of HSPI modified UF increases as the hydrolysis degree of HSPI increases at the hot-press temperature of 120°C and decreases at the hot-press temperature of 150°C. The best bonding strength is 1.53 MPa at the hot-press temperature of 135°C and improved 56.12% compared with UF. In addition, the formaldehyde emission is dramatically reduced. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41469. [ABSTRACT FROM AUTHOR]

The straw-bale has been widely used in the building field, compared to the traditional architecture material, it has lots of advantages such as high thermal resistance value, light weight, and environmental friendly material. In order to investigate the application effect, a solar greenhouse was designed and built with straw-bale. The performance of straw-bale wall solar greenhouse was evaluated, and compared with the soil wall and brick wall solar greenhouse. The hygroscopicity and desorption of straw, and thermal conductivity of straw-bale were evaluated. The moisture content of straw-bale, temperature and humidity, crop yield, morbidity of different solar greenhouse (soil wall, brick wall, and straw-bale wall) were discussed in the paper. The results showed that the maximum moisture content of straw was about 22.0% under the condition of 97% relative humidity and 25°C temperature, while the maximum moisture content of straw in the solar greenhouse was 23.6% during the experiment. The thermal conductivity of straw-bale with density of 0.20 g/cm3 was 0.069 W/(m·K), while the thermal conductivity of soil wall and brick wall were 1.210 W/(m·K) and 0.982 W/(m·K). The inertia index of straw-bale wall (0.46 m), soil wall (4.0 m) and brick wall (0.5 m) were 5.603, 43.513, and 4.636, respectively. The air temperature in the straw-bale wall solar greenhouse was 1.3°C higher than that in the brick wall solar greenhouse, and 2.1°C lower than that in the soil wall solar greenhouse. All the air temperature of solar greenhouse was above 9.0°C when the outdoor temperature was -7°C. The soil temperature in the straw-bale wall solar greenhouse was 1.2°C higher than that in the brick wall solar greenhouse, and 1.1°C lower than that in the soil wall solar greenhouse. All the soil temperature of solar greenhouse was above 12.1°C when the outdoor temperature was -7°C. The average air relative humidity of straw-bale wall, soil wall, and brick wall solar greenhouse were 75%, 87%, and 84%, respectively. The straw-bale displayed the adjusting capacity at some extent for the greenhouse air humidity due to the structural porosity of straw. It can not only improve the internal environment of greenhouse, but also restrain the occurrence of plant diseases. During full fruit period of the planted color peppers, the morbidity in the greenhouse with soil wall, brick wall, and straw-bale wall were 25%, 50% and 0, respectively, and the crop yields in the three kinds of greenhouse were 6 375, 7 130 and 6 833 kg, respectively. What's more, according to the design in the work, 35 000 kg straw (air dried) had been used to build the straw-bale wall solar greenhouse in this study. Also, the utilization rate of the land can improve by 34.6% due to reducing the wall thickness. In a conclusion, the straw bale has the potential to replace the soil or brick wall for building solar greenhouse thermal insulation wall. Further research should be paid attention on optimization of the straw greenhouse structural design, for example, the wall base and outer surface structural improvement, so as to elevate the thermal performance of straw bale greenhouse. [ABSTRACT FROM AUTHOR]

Due to advantages in being lightweight, inexpensive, biodegradable, and an easy process, composite materials with plant fiber filler have been widely applied in industry, agriculture, national defense, and other fields. In this study, flowerpots in a friendly environment were moulding-prepared through the procedure of mixing and hot-pressing in an oil hydraulic machine. The flowerpots were made of rice husk, rice husk power, and modified urea-formaldehyde resin. The rice husk or husk power components were added as reinforcing agents, while the resin component was added as a matrix material. The purpose of this paper is to discuss the influence of the dosage of urea-formaldehyde resin (UF), modified urea-formaldehyde resin (SUF), ratio of rice husk and rice husk power, and the wet cycle treatment on the mechanical property of the flowerpots. Thermal stability and microstructure of the flowerpots treated with the rewetting method were analyzed by Thermo-gravimetric Analysis (TGA) and a Scanning electronic microscope (SEM). The results showed that the mechanical properties of the flowerpots could be improved by applying modified urea-formaldehyde resin or adding rice husk power. With the dosage of modified UF, modulus of rupture, modulus of elasticity, and tensile strength of the straw flowerpot all improved. The modulus of rupture, modulus of elasticity, and tensile strength were 75.48 MPa, 16.06 GPa, and 17.44 MPa, respectively, when the ratio of reinforcing agent and matrix material was 1:0.5 (w/w) and the ratio of unbroken rice husk and rice husk power was 3:7 (w/w). Wet cycle treatment led mechanical parameter values of all formula specimens to decline in different degrees, with tensile strength and maximum bending deformation of SUF-pot specimens dropping most significantly. Using rice husk as the reinforcing agent (RH) in the wet cycle treatment resulted in the modulus of rupture, modulus of elasticity, and tensile strength of UF/RH to drop to 21.97%、 24.91%、 and 15.09%, while SUF/RH dropped 9.92%、 15.37%, and 30.10%, respectively. TGA analysis showed that the pyrolysis rate and mode of the straw flowerpot materials by wet cycle treatment had been slightly changed; namely materials mass loss rate was reduced and maximum thermal decomposition temperature increased. The SEM graphs of the composites fractured surface showed that the surface of the flowerpots treated by wet cycling had become rough. Some pieces of rice husk divorced from modified urea formaldehyde resin were clearly visible. Obviously, the interface between rice hull and SUF had become weak. This test showed that the straw flowerpots prepared with SUF resin were less stable than those prepared with UF resin, which implied that the former was liable to degrade. In regard to the production costs, the straw flowerpots are more than 10% lower than the plastic flowerpots. Substitution of plastic flowerpots with straw flowerpots would not only be beneficial in reducing white pollution from the use of plastic products, but also in promoting comprehensive utilization of the crop straw. Therefore, there will be an excellent market prospect of straw flowerpots. [ABSTRACT FROM AUTHOR]

It is difficult to recover the residual heat from flue gas when supercritical carbon dioxide (S-CO2) cycle is used for a coal fired power plant, due to the higher CO2 temperature in tail flue and the limited air temperature in air preheater. The combined cycle is helpful for residual heat recovery. Thus, it is important to build an efficient bottom cycle. In this paper, we proposed a novel exergy destruction control strategy during residual heat recovery to equal and minimize the exergy destruction for different bottom cycles. Five bottom cycles are analyzed to identify their differences in thermal efficiencies (ηth,b), and the CO2 temperature entering the bottom cycle heater (T4b) etc. We show that the exergy destruction can be minimized by a suitable pinch temperature between flue gas and CO2 in the heater via adjusting T4b. Among the five bottom cycles, either the recompression cycle (RC) or the partial cooling cycle (PACC) exhibits good performance. The power generation efficiency is 47.04% when the vapor parameters of CO2 are 620/30 MPa, with the double-reheating-recompression cycle as the top cycle, and RC as the bottom cycle. Such efficiency is higher than that of the supercritical water cycle power plant. [ABSTRACT FROM AUTHOR]

The effects of soil burial on the biodegradation of biocomposite flower pots (BFP) made from straw fiber (SF) and hydrolyzed soy protein isolate/urea/formaldehyde (HSPI/U/F) copolymer resin were studied in detail. The microstructure, crystallinity, functional groups, mechanical, degradation and thermal property of the prepared SF with HSPI/U/F copolymer resin have been studied, and the degradation mechanism was also elucidated. XRD results showed that the bond breakage between SF and HSPI/U/F copolymer resin induced a decrease in relative degradation-resistant crystal structures. FTIR spectra showed that the methylolated HSPI units could form a cross-linking network with U/F and SF. The BFP degradation after soil burial was mainly attributed to the effects of microorganisms. The degradation products were environmentally friendly, because they were degradable and could fertilize the soil. In addition, the U/F adhesives were slightly degraded by the microorganisms due to the HSPI in the pots. The TG and DSC results showed that the molecular motion of the BFP matrix could be restricted by the degradation action and the content of HSPI, resulting in decreased crystallization enthalpy and showing good thermal property. The tensile strength of different reinforced samples was not significantly reduced in comparison to U/F resin, and still kept good mechanical performance. Thus, the prepared SF reinforced HSPI/U/F copolymer resins could have good potential for use in the field of biodegradable flower pots because of their good thermal property, mechanical property, biodegradability, and relatively low cost. [ABSTRACT FROM AUTHOR]