Visible light positioning (VLP) is widely believed to be a cost-effective answer to the growing demand for service-based indoor positioning. Meanwhile, high accuracy localization is very important ...for mobile robots in various scenes including industrial, domestic and public transportation workspace. In this paper, an indoor robot VLP localization system based on Robot Operating System (ROS) is presented for the first time, aiming at promoting the application of VLP in mature robotic system. On the basis of our previous researches, we innovatively designed a VLP localization package which contains the basic operation control of the robots, the features extraction and recognition of the LED-ID, cm-level positioning, and robust dynamic tracking algorithms. This package exploited the proposed lightweight algorithm, distributed framework design, the loose coupling characteristics of the ROS, and the message communication methods among different nodes. What's more, an efficient LED-ID detection scheme is proposed to ensure the lightweight and accuracy of the positioning. A prototype system has been implemented on a Turtlebot3 Robot 11 Experiment Demonstration is available at: https://kwanwaipang.github.io/Image/ROS.mp4.. Experimental results show that the proposed system can provide robot indoor positioning accuracy within 1 cm and an average computational time of only 0.08 s.
Prebaked carbon anode is the primary consumable material in the aluminum reduction cell, and its quality directly affects the energy consumption of aluminum production. An impregnation-baking process ...of the anode was proposed to reduce the anode porosity, improve the quality of the anodes, and reduce additional carbon consumption. The theoretical analysis and industrial testing on the impregnation-baking process were carried out. Firstly, the coal tar pitch was immersed into the anode carbon block through the impregnation process. An anode impregnation model was developed and used for theoretical calculations to analyze the effects of pressure and temperature on the impregnation process. The accuracy of the model was verified experimentally. Secondly, the impregnated anodes were placed in an electromagnetic induction heating furnace for baking to carbonize the immersed pitch. The thermogravimetric and pyrolysis kinetics methods were used to analyze the baking process of the impregnated anodes. Finally, the impregnated-baked anodes were compared with common anodes regarding their impact on the technical and economic indicators of the aluminum electrolysis process in industrial tests. The results showed that the physicochemical properties of the impregnated-baked anodes were significantly improved, with the bulk density increase of 0.1 g/cm3, air permeability reduction of 0.54 nPm, compressive strength enhancement of 9.43 MPa, and electrical resistivity decrease of 10 uΩ·m. The anode service life was increased from 31 to 35 days, the current efficiency was increased by 0.44 %, and the operating voltage was reduced by 17 mV, which improved economic benefit significantly.
•An impregnation-baking process of the anode for aluminum electrolysis was proposed.•An anode impregnation model was developed.•Baking process was optimized by thermogravimetric and pyrolysis kinetics analysis.•A significant improvement in the economic benefits of using impregnated-baked anode.
Tobacco exposure is considered to be a risk factor for reduced bone mineral density (BMD), which may result in osteopenia. Cotinine, a metabolite of nicotine, is commonly utilized as a marker of ...tobacco exposure. Nevertheless, there are limited clinical data on the associations between osteoporosis (OP) or osteopenia and smoking status or serum cotinine level.
We thoroughly examined the NHANES cross-sectional data from 2005 to 2010, 2013 to 2014, and 2017 to 2018. Multivariate logistic regression models were applied to assess the associations among smoking status and serum cotinine levels as well as OP and osteopenia. The relationships between serum cotinine level and OP and osteopenia were also assessed using the restricted cubic spline (RCS) method.
A total of 10,564 participants were included in this cross-sectional study. The mean age of the study population was 64.85 ± 9.54 years, and the patients were predominantly male (51.9%). We found that the relationships between higher serum cotinine levels (≥3 ng/ml) and the prevalence of osteoporosis (Model 1: OR=2.27 1.91-2.69; Model 2: OR=2.03 1.70-2.43; Model 3: OR=2.04 1.70-2.45; all
for trend <0.001) remained significant after adjustment for covariates by applying the lowest serum cotinine levels (<0.05 ng/ml) as the reference. Similar results were observed for current smokers, who were more likely to develop OP compared with nonsmokers (Model 1: OR=2.30 1.90-2.79; Model 2: OR=2.16 1.77-2.64; Model 3: OR=2.16 1.77-2.65). Moreover, higher serum cotinine levels were found to be strongly and positively correlated with the prevalence of osteopenia (OR=1.60 1.42-1.80). A similar relationship was observed between current smokers and the prevalence of osteopenia compared with nonsmokers (OR=1.70 1.49-1.94). RCS regression also showed that serum cotinine levels were nonlinearly and positively correlated with OP and osteopenia, with inflection points of 5.82 ng/ml and 3.26 ng/ml, respectively.
This study showed that being a smoker was associated with the prevalence of OP or osteopenia compared with being a nonsmoker and that there was a strong nonlinear positive dose-response relationship between serum cotinine levels and OP and osteopenia.
Aiming at the current lack of thermodynamic parameters related to the preparation of aluminum–silicon–iron alloys from spent refractory materials in aluminum electrolytic cells, the Miedema model was ...used to calculate the thermodynamic parameters of Al–Si, Al–Fe, and Si–Fe binary alloys. On this basis, the Toop model was combined to calculate the mixing enthalpy ΔH, excess entropy S E , excess Gibbs free energy G E , and component activity α of Al–Si–Fe ternary alloys. The results show that ΔH, S E , and G E of binary alloys are all negative values. The properties of the Al element and Si element are similar, and they are different from the Fe element. The ternary alloys also have negative values of ΔH, S E , and G E in the alloy composition range, and their values change obviously in the region where the content of Fe is high or low. The activity values of all components decrease dramatically along with the diminishing of the corresponding molar fractions, and the activity values of Al, Si, and Fe are smaller in the central portion of the triangle of ternary components. It indicates that there is a strong interaction between the three elements, which easily forms ternary intermetallic compounds.
The electro-thermal state of a busbar system of electrolysis cells for aluminum production represents the main factor affecting hydromagnetic stability and current distribution. Based on the busbar ...system of a 500 kA aluminum electrolytic cell, an overall busbar electro-thermal field coupling calculation model was established based on ANSYS. The characteristics of busbar temperature, current density, and voltage drop distribution were analyzed. In addition, the electro-thermal distribution of the busbar system was simulated under different current intensities, ambient temperatures, and heat transfer coefficients. The results show that the temperature distribution of the riser busbar and the cathode busbar is higher in the middle location and tends to decrease along the two sides. Differences in heat conduction and heat dissipation environment are the main factors affecting the distribution of the busbar system’s electro-thermal field, while the Joule heat of the current is not the major factor. Increasing the current intensity will increase the average temperature and average voltage drop of the busbar. With an increase in the ambient temperature, the average busbar temperature increases significantly, and the voltage drop of the busbar also increases. With an increase in heat transfer coefficient, the average temperature and voltage drop of the busbar decreases.
A large amount of carbon dust is generated in the process of aluminum smelting by molten salt electrolysis. The carbon dust is solid hazardous waste but contains a large quantity of recyclable ...components such as carbon and fluoride. How to recycle carbon dust more effectively is a challenge in the aluminum electrolysis field. In this study, X-ray diffraction, scanning electron microscope, and other methods were used to analyze the phase composition of electrolytic aluminum carbon dust. The effects of particle size distribution of carbon dust, impeller speed, reagent addition, mixing time, and flotation time on the flotation recovery of carbon dust were studied. The optimal flotation conditions were obtained and the flotation products were analyzed. The results show that the optimal particle size distribution is 70% of particles below 200 mesh, corresponding to a grinding time of 11 min. The optimum speed of the flotation machine was to be between 1600 and 1800 r/min with the best slurry concentration of 20–30% and 5 min mixing time, and the collector kerosene was suitable for adding in batches. Under the above conditions, the recovered carbon powder with a carbon content of 75.6% was obtained, and the carbon recovery rate was 86.9%.
To investigate the impact of the bone mass and volume of the low-density area under the tibial plateau on the lower limb force line by finite element analysis, offering mechanical evidence for ...preventing internal displacement of the lower limb force line in conjunction with knee varus in patients with knee osteoarthritis (KOA) and reducing bone mass under the tibial plateau.ObjectiveTo investigate the impact of the bone mass and volume of the low-density area under the tibial plateau on the lower limb force line by finite element analysis, offering mechanical evidence for preventing internal displacement of the lower limb force line in conjunction with knee varus in patients with knee osteoarthritis (KOA) and reducing bone mass under the tibial plateau.A healthy adult was selected as the study subject, and X-ray film and CT imaging data were acquired. Mimics 21.0 software was utilized to reconstruct the complete knee joint model and three models representing low-density areas under the tibial plateau with equ
A new method for the disposal of the spent refractory materials by adding them directly to electrolytic cells requires our better knowledge of the Na3AlF6–Al2O3–SiO2 melt system. The development of ...computational materials science offers us a new way to avoid the limitation of the experiment under a strong corrosive environment at high temperatures. First-principles simulation is applied to study the structure information, electronic properties, and transport properties of the system. The study reveals that the main Si and Al ions in the melt are complex ion groups such as SiF2O22–, SiFO33–, SiF3O23–, AlF2O23–, AlF3O2–, and AlF4O3–. Tangled structures like SiAlO3F54– also exist in the melt. The average coordination number of Al–F and Si–F is 3.21 and 2.45, respectively. O ions mainly act as bridge ions in the melt. The bonding ability of Al with O ions is stronger than that of Si with O ions. Moreover, the Al–O bond is mainly covalent, while the Al–F bond is basically ionic characters. The order of diffusion ability of ions from large to small is Na, F, Al, Si, and O. Addition of SiO2 into the Na3AlF6–Al2O3 molten salt causes an increase of the viscosity and a decrease of ionic conductivity.
Despite the dominance of the blast furnace ironmaking process, more attention is being paid to the new technologies with lower energy consumption and carbon dioxide emissions. A novel flash ...ironmaking technology using pulverized coals and iron concentrates as raw materials, which is different from flash ironmaking with the reductive gas as the reducing agent, is studied. In order to obtain the flow patterns, temperature, and gas composition distribution, as well as particle trajectories in the reaction shaft of the flash ironmaking furnace, the Euler–Lagrangian model with a custom user defined function (UDF) code is used to simulate the processes of the fluid flow, heat and mass transfer, and chemical reactions, including the combustion reaction of pulverized coals and reduction reaction of iron concentrates. The results indicate that the flow patterns, temperature, and gas composition distributions present symmetrical distribution characteristics. The central oxygen expands rapidly after entering the reaction shaft and its distribution is approximately bell-shaped. The temperature distribution in the reaction shaft is wing-shaped. The maximum temperature, 2615 K, is reached at 5 m below the roof of the reaction shaft. The O2 is quickly consumed after entering the reaction shaft. At 6 m below the roof of the reaction shaft, the oxygen concentration becomes almost zero, with the CO concentration reaching the highest. The Fe2O3 and FeO in the iron concentrates are mostly reduced to Fe at 9 m below the roof of the reaction shaft, and more than 95 wt% iron particles could be obtained within 1.2–7.7 s.
In this paper, a hybrid scheme based on the ray tracing method and machine learning for the field strength prediction is presented. It uses a triangular face as a basic unit to simulate in CST and ...gets lots of training data. This method can be divided into two main parts - predicting the field strength with machine learning in near field and converting field strength to rays in far field. In contrast to the results of finite integral (FIT), mean relative error of results predicted by the new model is 0.04 in near field and 0.0583 in far field. And in this way, high prediction accuracy is achieved with less computation time. Comparisons of time performance between the new method, FIT and ray tracing method are presented in the last.
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