CFD simulation of particle mixing in a fluidized bed

This project is to do the research of CFD simulation of particle mixing in a fluidized bed.Nowadays, fluidized bed is widely used in different kinds of industry, such aspower plant, petroleum industry and food processing industry. The objectives of this project are to study the mixing and segregation phenomena in a fluidized bed and to design distributors with low pressure drop operation. Fluidized beds suspend solid fuels on upward-blowing jets of air during the combustion process. The main characteristicof fluidized bed are pressure drop, fluid velocities, bubble size and bed heightComputational fluid dynamics (CFD) simulation is the method to study this project. Firstly, Ergun 6.2 software is used to study particle mixing and segregation phenomenaSecondly, 3D geometry of fluidized bed is drawn by using Solidworks 2012. Flowsimulation program is used to study pressure drop in the fluidized bed 3D drawing.Minimum fluidized velocity and operation point is found by using Ergun 6.2 softwarePressure drop is found by using Flow Simulation program. Compare with otherresearcher ’s results these simulation results are accepted

A modelling study of filtration mechanisms for micron-particles filtration in fibrous diesel particulate filters

Diesel exhaust has a particle size less than 10 µm; for the visualisation of micron-particles’ motion, the numerical method is applied. A coupled lattice Boltzmann method and discrete element method is implemented to investigate the mechanism that governs particle-gas flows and particle fouling in idealised 2D fibrous DPFs. The open-source library, Mechsys, is validated and then implemented for idealised filter configurations. The initial parameters of simulations are filter configurations, initial velocities of fluid, the density of the particles, porosity of the filters, with the particle diameter being 10 µm. These results consider the numbers of particle deposition, filtration time, pressure drop, and location of particle deposition. The results have shown that the different filter configurations have different filtration performances for different velocities or densities. The filters of 75% porosity have better than 90% porosity filtration performance for 10 µm particles

A Biologically Inspired Height-Adjustable Jumping Robot

This paper presents the design and development of a miniature integrated jumping and running robot that can adjust its route trajectory and has passive self-righting. The jumping mechanism of the robot was developed by using a novel design strategy that combines hard-bodied animal (springtail) and soft-bodied animal (gall midge larvae) locomotion. It could reach a height of about 1.5 m under a load of 98.6 g and a height of about 1.2 m under a load of 156.8 g. To enhance the jumping flexibility of the robot, a clutch system with an adjustable height and launch time control was used such that the robot could freely switch to appropriate jumping heights. In addition, the robot has a shell with passive righting to protect the robot while landing and automatically self-righting it after landing, which makes the continuous jumping, running, and steering of the robot possible. The two-wheel mechanism integrated at the bottom of the housing mechanism provides the robot with horizontal running locomotion, which is combined with the vertical jumping locomotion to obtain different locomotion trajectories. This robot has the functions of obstacle surmounting, track adjustability, and load- and self-righting, which has strong practical application value

Microwave-mediated magnon–atom interactions: Two-mode higher-order squeezing of two YIG spheres

We propose an efficient scheme to realize almost perfect higher-order squeezing of two YIG spheres via microwave-mediated magnon–atom interactions. It is assumed that two microwave cavity modes are coupled to two YIG spheres by the magnetic dipole interaction and a superconducting artificial atom by the electric dipole interaction, respectively. When the microwave cavity fields are tuned to be far detuned from the dressed atomic Rabi sidebands and the magnon frequencies, the coherent coupling between two magnons and the artificial atom can be established via virtual photon exchange. We find that a pair of Bogoliubov modes composed of two magnon modes are cooled to the vacuum state through the atomic engineered dissipation, resulting in an ideal two-mode higher-order squeezing state of the YIG spheres. The solid-state device may find realistic applications in high-precision measurement and quantum sensing technology

A Novel Type of Wall-Climbing Robot with a Gear Transmission System Arm and Adhere Mechanism Inspired by Cicada and Gecko

To support the inspections of different contact walls (rough and smooth), a novel type of wall-climbing robot was proposed. Its design embodied a new gear transmission system arm and an adherence mechanism inspired by cicadas and geckos. The actuating structure consisted of a five-bar link and a gear transmission for the arm stretching, which was driven by the servos. The linkers and gears formed the palm of this robot for climbing on a line. Moreover, the robot’s adherence method for the rough surfaces used bionic spine materials inspired by the cicada. For smooth surface, a bionic adhesion material was proposed inspired by the gecko. To assess the adherence mechanism of the cicada and gecko, the electron microscope images of the palm of the cicada and gecko were obtained by an electron microscope. The 3D printing technology and photolithography technology were utilized to manufacture the robot’s structures. The adherence force experiments demonstrated the bionic spines and bionic materials achieved good climbing on cloth, stones, and glass surfaces. Furthermore, a new gait for the robot was designed to ensure its stability. The dynamic characteristics of the robot’s gear transmission were obtained

Investigating the Usage Patterns of Park Visitors and Their Driving Factors to Improve Urban Community Parks in China: Taking Jinan City as an Example

Urban community parks have significant benefits for city residents, both physical and spiritual. This is especially true in developing countries, such as China. The purpose of our study is to describe the current situation of the community parks in five main districts of Jinan City while recognizing features of the community parks that influence usage patterns. Our study also means to determine the desired improvements of visitors that promote access to and use of community parks on the basis of the Chinese context. We conducted a survey among 542 community park visitors and obtained valid responses. The findings of respondents show that community parks are mostly used by people over 55 years (34.7%) and children under 10 years (23.6%). The main motives for using community parks are for exercise (24.2%) and to socialize with others (21.6%). The majority of respondents (65.7%) rated the community park as satisfactory and considered only a few improvements needed. Regarding the desired improvements, numerous respondents mentioned adding more physical training facilities (13.3%) and activity areas (7.6%), as well as emergency call buttons in areas frequented by children and older people (7.6%). Furthermore, most of the respondents (79.9%) indicated that they would like to use the community parks more frequently if there is additional progress to make the parks more attractive, cleaner, and friendlier. These results can help park designers, government agencies, and community groups to provide the planning and design strategies for community parks to promote their upgrading in China

Study the Parametric Effect of Pulling Pattern on Cherry Tomato Harvesting Using RSM-BBD Techniques

Detachment of fruit from the plants with separation force is important in robotic harvesting. Compared with twisting pattern and bending pattern, the pulling pattern for cherry tomato harvesting is more simple, more flexible, and easier to implement in robotic harvesting. It was found that the detachment force is closely related to the location of the fruit separation. However, in the pulling pattern, analysis of the effect of harvesting parameters of cherry tomatoes at the calyx/fruit joint has still not been carried out in depth. In this paper, the goal of this research was to investigate the effect of different harvesting parameters on the minimal detachment force of cherry tomatoes at the calyx/fruit joint. Experiments were designed according to response surface methodology Box–Behnken design by maintaining three levels of three process parameters—grasping angle, horizontal angle, and pitching angle. Results showed that the pitching angle is the most important parameter, and the grasping angle has little effect on the detachment force, and the detachment force was found within the range of 0.58 N to 2.46 N. Results also revealed that the minimum separation force of the cherry tomato harvesting at the calyx/fruit joint was obtained by the optimum conditions of the grasping angle of 68°, the horizontal angle of 135° and the pitching angle of 0°. Moreover, desirability function has also been used to optimize the angle parameters. The confirmation experiments validate the reliability and capability of the developed model

Aerosol Property Analysis Based on Ground-Based Lidar in Sansha, China

Marine aerosol is one of the most important natural aerosols. It has a significant impact on marine climate change, biochemical cycling and marine ecosystems. Previous studies on marine aerosols, especially in the South China Sea, were carried out by satellite and shipborne measurements. The above methods have drawbacks, such as low temporal–spatial resolution and signal interference. However, lidar has high accuracy and high temporal–spatial resolution, so it is suitable for high-precision long-term observations. In this work, we obtain marine aerosol data using Mie Lidar in Sansha, an island in the South Chain Sea. Firstly, by comparing boundary layer height (BLH) between Sansha and Hefei, we found that Sansha’s boundary layer height has significant differences with that of inland China. Secondly, we compare the aerosol extinction coefficients and their variation with height in Sansha and Hefei. Finally, we obtain hourly averaged aerosol optical depth at Sansha and explore its relation with weather. To analyze the AOD–weather relation, we select three meteorological factors (sea surface temperature, mean sea level pressure and 10 m u-component of wind) based on their feature importance, which is determined by random forest regression. We also analyze the relationship between AOD and the above meteorological factors in each season separately. The results show that there is a strong relation between the meteorological factors and AOD in spring and summer, while there is no clear correlation in fall and winter. These analyses can provide valid data for future researches on marine aerosols in the South China Sea

Spin two-axis-twisting via coherent population trapping based cavity QED

We present a spin two-axis-twisting mechanism via coherent population trapping (CPT) based atom–photon interactions. CPT happens and the atoms are trapped in the dark state (coherent superposition of two ground states) when the ground states are resonantly coupled to a common excited state. Close to CPT, the atoms behave as two dark-state based spins, which interact with the common cavity vacuum fields. The otherwise nonexistent interaction is created between them and is identified to be responsible for the two-axis-twisting of the ground state spin. The essential difference from the previous schemes is the compatibility of the twisting spin squeezing with the resonant atom-light interaction. The CPT resonant unit serves as a kind of new ingredients for the quantum networks

Bionic Design of a Miniature Jumping Robot

In response to the problem of low energy storage density in the structure of existing miniature jumping robots, this study designed a parallel single-degree-of-freedom double six-link jumping robot by imitating the physiological structure and jumping mechanism of wax cicadas. The designed six-link mechanism was first mathematically modeled, and to accommodate the jumping structure of this robot, a six-link mechanism with a smaller cam pushrod stroke was obtained by optimizing the linkage size and position parameters in the model. The dynamics of the robot’s jumping process were then analyzed utilizing the second type of Lagrange equation to determine the joint angles of the robot’s jumping phase. The results were compared with an ADAMS-based jumping simulation to verify the validity of the analysis of the dynamics. The feasibility of the structural design was then validated using ADAMS simulations. Finally, a physical prototype of the jumping robot was produced and tested; the findings revealed that the robot had good jumping performance, was stable in the air, fully discharged 600.2 mJ of energy, and was able to overcome obstacles measuring 220 mm in height and 330 mm in distance. The design of the jumping robot provides a novel approach to improving energy storage density and serves as a foundation for future research on footed jumping robots