In recent years, great breakthroughs have been made in object detection. However, performance of the most algorithms declines significantly when detecting small objects in an image. Thus, multi-scale ...feature maps are often used to develop network variants to generate multi-scale representations. Existing feature pyramid-based methods tend to keep the number of channels consistent and fuse different scales by adding corresponding elements or channel concatenation, which is prone to lose low-level detailed feature information in feature fusion process. To solve this problem, a bi-directional stepped concatenation feature pyramid construction method based on SSD (BSCF-SSD) is proposed. The stepped concatenation strategy helps to avoid the loss of information at the current layer during the pyramid construction process, and the bi-directional tactic ensures the fusion features contain both detailed and semantic information. Furthermore, an attentional interaction module is designed to better aggregate dual-stream features to improve network performance. The proposed method improves the detection accuracy of small objects with less speed loss. Experimental results show that the method achieves 80.3% and 82.4% mAP on Pascal VOC2007 using VGG16 and Resnet50, respectively. On the special aviation object dataset UCAS-AOD, BSCF-SSD with VGG16 still achieves moderate improvement.
Zhoushan cattle are an endangered cattle breed in the Zhoushan islands in China. Since Zhoushan cattle have been bred in isolation, they show unique characteristics, such as dark black coat colour. ...However, no studies have been conducted on the genome of Zhoushan cattle. Here, we performed whole-genome sequencing of seven individuals of Zhoushan cattle and nine cattle in Wenling, geographically close to the Zhoushan islands. By integrating our data and publicly-available data, we found that Zhoushan cattle are genetically highly similar to Bos indicus cattle in south-eastern China. Furthermore, by identifying the genomic regions shared between Zhoushan cattle and Angus cattle, a Bos taurus breed, we found that the p.F195L mutation in melanocyte-stimulating hormone receptor (MC1R) could be associated with their dark black coat colour. Taken together, our results provide a valuable resource for characterising the uniqueness of Zhoushan cattle.
In the field of detection, there is a wide gap between the performance of small objects and that of medium, large objects. Some studies show that this gap is due to the contradiction between the ...classification-based backbone and localization. Although the reduction in the feature map size is beneficial for the extraction of abstract features, it will cause the loss of detailed features in the localization as traversing the backbone. Therefore, an interactive multi-scale feature representation enhancement strategy is proposed. This strategy includes two modules: first a multi-scale auxiliary enhancement network is proposed for feature interaction under multiple inputs. We scale the input to multiple scales corresponding to the prediction layers, and only passes through the lightweight extraction module to extract more detailed features for enhancing the original futures. Moreover, an adaptive interaction module is designed to aggregate the features of adjacent layers. This approach provides flexibility in achieving the improvement of small objects detection ability without changing the original network structure. Comprehensive experimental results based on PASCAL VOC and MS COCO datasets show the effectiveness of the proposed method.
•An auxiliary multi-scale input network for enhancing shallow features.•Interactive multi-scale features for aggregating contextual information.•An adaptive factor embedded in the interactive module to control the fusion ratio.
Herein,
a new clean extraction technology for the decomposition
of bastnasite concentrate by utilizing the microwave radiation is
proposed, which prevented Ce(III) from being oxidized to its ...tetravalent
form. The process includes microwave radiation roasting to nonoxidatively
decompose the bastnasite concentrate, mechanism analysis of Ce(III)
not being oxidized to Ce(IV), hydrochloric acid leaching of the nonoxidative
roasted ore, and kinetics analysis of the leaching process. The experiments
were carried out concentrating on the effect of roasting temperature
and holding time on the decomposition rate of the bastnasite concentrate
and the oxidation rate of cerium and the effect of acidity, liquid–solid
ratio, leaching temperature, and stirring rate on the leaching kinetics
of the nonoxidative roasting ore. When the roasting temperature is
1100 °C, the holding time is 20 min, and the
m
(C)/
m
(REFCO
3
) ratio is 0.2, the results
show that the leaching efficiency of rare earths can reach 85.45%
under the conditions 3 mol/L HCl, 90 °C, 60 min, 9 mL/g liquid–solid
ratio, and 300 rpm stirring rate. The X-ray diffraction and scanning
electron microscopy analyses of the samples before and after acid
leaching show that the rare earth oxides were completely leached and
Ce(III) was not oxidized to its tetravalent form. The apparent activation
energies of leaching rare earths were calculated as 14.326 kJ/mol,
and the HCl leaching process can be described by a new variant of
the shrinking-core model, in which both the interfacial transfer and
the diffusion through the product layer influenced the reaction rate.
Furthermore, a semiempirical rate equation was created to describe
the leaching process of the nonoxidative roasted ore.
The investigation of the dielectric properties of bastnasite concentrate has critical directing centrality for the microwave roasting process of bastnasite concentrate. The dielectric properties are ...correlated with information such as thermogravimetry–differential scanning calorimetry and temperature rise curves. This combination permits a targeted study of the mechanism of the microwave roasting process, providing new evidence about the unique conditions of this microwave roasting process. This work also explores the response surface methodology based on a central composite design to optimize the microwave non-oxidative roasting process. Single-factor tests were conducted to determine the suitable range of factors such as the content of activated carbon, holding time, and roasting temperature. The interactions between parameters were investigated through the analysis of variance method. It was indicated that the models are available to navigate the design space. Also, the optimal roasting temperature, content of activated carbon, and holding time were 1100 °C, 20%, and 21.5 min, respectively. Under these conditions, the decomposition rate of bastnasite concentrate (hereinafter to be referred as DRBC) and the oxidation rate of cerium (hereinafter to be referred as ORC) was 99.8% and less than 0.3%, respectively. The new non-oxidizing roasting method significantly shortens the roasting time, reduces the energy consumption, and has great significance for industrial applications.
This article introduces an efficient decomposition process that uses sodium carbonate (Na2CO3) and activated carbon (C) as additives to decompose Bayan Obo mixed rare earth concentrate (hereinafter ...to be referred to as RE concentrate) by nonoxidative microwave radiation roasting. The roasting temperature, holding time, and contents of Na2CO3 and activated carbon are investigated. The optimum process parameters for decomposition are 800 °C and 30 min. The ratio of m(Na2CO3)/m(RE concentrate) is 0.5, and the ratio of m(C)/m (ER concentrate and Na2CO3) is 0.2 based on experimental data. Under the above conditions, the decomposition rate (shortened to DR) of RE concentrate is 98.58%, and the removal rates (shortened to CRs) of fluorine (F) and phosphorus (P) reached 80.35 and 46.75%, respectively. These rates are higher than traditional oxidation roasting under the same conditions. The three reasons for the result are the unique microwave heating characteristics, the overall efficient reaction of the mixture (RE concentrate, Na2CO3, and activated carbon), and the high nonoxidation rate of cerium. For these reasons and large experimental data, the reaction rate of the mixture is improved, and the efficiency of dilute hydrochloric acid for leaching rare earth elements is enhanced. In this article, the valence of rare earth elements in the roasted ore is all in the form of trivalence. Importantly, this nonoxidative roasted product can avoid the generation of chlorine in hydrochloric acid leaching. Moreover, such a short holding time is scarce in traditional roasting. When the mixture was roasted by utilizing microwave heating, the sinter phenomenon of the roasted product was avoided at high-temperature roasting. Finally, the surface morphology of RE concentrate at different conditions was observed by scanning electron microscopy (SEM) analysis, which can be used to compare the specific differences of roasting methods. According to these results, this process is beneficial for the decomposition of RE concentrate in terms of Na2CO3 roasting and is helpful for improving the clean and green technology method of hydrometallurgy.
Time synchronization is the key technology of real-time integrated navigation, and its error decides the precision of integrated navigation. Global navigation satellite system (GNSS) and inertial ...navigation system (INS) real-time integrated navigation requires the fusion of GNSS and inertial measurement unit (IMU) data at 1PPS. However, due to data computation and circuit delay, it is impossible to receive two data simultaneously at 1PPS, resulting in the inability to achieve high-precision data fusion. In response to this issue, this paper proposes a novel time synchronization strategy, which first saves IMU data, waits for GNSS data to be received, and then fuses the two. The key to this approach is to ensure that the saved IMU data is processed within a sampling interval. This article adopts a one-step predictive Kalman filter algorithm to place the state prediction covariance matrix in the traditional algorithm into the measurement update process for execution so that only INS mechanization algorithms are executed during the state prediction process, which can significantly reduce the code runtime and ensure that the saved IMU data can be processed promptly. The correctness of the proposed algorithm was verified through real-time vehicle experiments in the real world. The test results show that data time synchronization can be achieved accurately to the order of microseconds with the proposed synchronization approach. The integrated navigation system with this strategy achieves performance with comparable real-time positioning and post-processing positioning accuracy.
As the production of electric vehicles and lithium-ion batteries continues to rise, concerns over resource scarcity and supply shortages of critical metals, including Cu, Ni, Co, Mn, and Li, have ...become increasingly urgent. To address these concerns and promote environmental protection, there is a growing demand for the recycling of hazardous waste containing these critical metals as secondary resources. Therefore, this paper proposes a novel synergistic solvent extraction system of D2EHPA-NNPA, which fills a gap in the lack of a suitable extraction system for the hydrometallurgical industry of secondary resources containing Cu, Ni, Co, Mn, and Li. With the specific extraction sequence of D2EHPA-NNPA, a novel process has been designed and proposed for the stepwise extraction of Cu, Ni, Co, Mn, and Li from secondary resources, which significantly simplifies process flows while avoiding cross-contamination of the extractants and the production of industrial wastewater. Furthermore, the proposed "extraction-scrubbing-stripping" process has been investigated from both macroscopic and microscopic perspectives, demonstrating that the novel synergistic solvent extraction system of D2EHPA-NNPA is a viable option for industrial applications to promote a circular economy and achieve sustainability objectives.
Schematic structure of D2EHPA and NNPA and the metal extraction pH isotherms of their synergistic extraction system.
Various pathogenic microorganisms present in municipal solid waste (MSW) can pose significant hazards to both the environment and public health. Spraying Slightly Acidic Electrolyzed Water (SAEW) is ...an effective method for decontaminating microorganisms in the air and on surfaces in the waste sorting rooms. SAEW treatment, with an effective chlorine concentration (ECC) of 28.4–44.5 mg/L and a pH range of 5.0–6.5, was conducted in the waste sorting rooms of the old, high-rise, and villa residential communities in Shanghai, China. The efficacy of SAEW treatment was assessed by examining the microbial population in the air, on waste containers, on sanitation workers' hands, and the microbial community structure of MSW samples. SAEW treatment resulted in the total bacterial reduction ranging from 0.07 to 1.70 log10 colony-forming units (CFU)/cm2 on waste containers, with corresponding reduction efficiencies between 15.7% and 98.0%. Additionally, the positive rates of coliforms were decreased by 18.7%–95.2%. Furthermore, the application of SAEW demonstrated a significant impact on reducing airborne bacterial and fungal levels. SAEW was proven effective on object surfaces, in the air and on human skin, achieving disinfection efficiencies ranging from 22.7% to 54.3% on sanitation workers’ hands. And the most significant inhibition of microbial growth was observed in the waste sorting room of the villa residential community. The microbial diversity and structure of MSW samples exhibited noticeable differences before and after the SAEW application. These findings suggest that SAEW holds significant potential as an ideal, environmentally friendly broad-spectrum disinfectant for preventing and controlling microbial contamination in the waste sorting rooms.
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•Microbial contamination was reduced with SAEW in waste sorting rooms.•SAEW was proven effective on object surfaces, in the air and on human skin.•SAEW changed the microbial diversity and structure of MSW samples.•The bacterial reduction efficiencies of SAEW on waste containers were 15.7%–98.0%.
Moso bamboo plantations suffer from phosphorus (P) limitations. A better understanding of soil P cycling contributes to the sustainable management and development of the bamboo forests. In this ...study, different phosphate-solubilizing bacteria (PSB) were applied to soils to stimulate bamboo growth, and the metagenomics method was employed to investigate the changes in soil microbial communities and relative abundances of functional genes. Meanwhile, soil properties and bamboo biomass and physiological indices were also quantitatively analyzed. The PSB inoculations changed soil P fractions and significantly elevated available P (AP) content by stimulating phosphatase activity and functional genes involved in P-transformation. The PSB inoculations significantly stimulated soil acid phosphatase activities and enhanced the relative abundances of functional genes associated with inorganic P-solubilization and organic P-mineralization. Moreover, increased soil available nutrients were beneficial to the moso bamboo growth, and the bamboo biomass in the different treatments increased by from 32.43 % to 69.04 % compared with the control treatment. Significant increases in root activity, carotenoid, chlorophyll a and total chlorophyll contents after the PSB inoculations also contributed to moso bamboo growth. The PSB strain inoculations shaped soil microbial communities and increased microbial connections. Besides adjusting soil P supplies and functional genes, the PSB also promoted the moso bamboo growth by increasing soil mineral N, AK and bamboo chlorophyll contents and stimulating functional microorganisms. Our study could provide a theoretical basis to improve soil nutrient utilization for moso bamboo with the PSB inoculations.
•The PSB accelerated soil P transformation by functional gene and phosphatase.•The PSB significantly shaped microbial community structures and connections.•Available nutrient contributed to bamboo growth and physiological indexes.•Chlorophyll and soil K increased by the PSB had positive effects on bamboo biomass.•The PSB significantly contributed to carotenoid and root activity of bamboo.
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