Facile Synthesis and Special Phase Transformation of Hydrophilic Iron Oxides Nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs), γ-Fe2O3, with hydrophilic surfaces are fabricated in ethylene glycol solutions, without surfactant or additive, by solvothermal process from α-Fe2O3 nanoparticle as precursors. With the addition of a trace of hydrazine hydrate, the cubic phase Fe3O4 nanoparticles are obtained instead of γ-Fe2O3. The saturation magnetization value of γ-Fe2O3 nanoparticles is up to 74.3 emu/g. This study provides a low cost, safe, and universal route to serve as excellent biocompatibility magnetic core for future applications in biomedical, agriculture, and horticulture applications

Meso numerical study on the failure mechanism of rock slope with bedding intermittent joints

Taking the Muliashi north open-pit mine in Zambia as a case study, the failure mechanism of rock slope with intermittent bedding joints was investigated from a meso mechanical viewpoint using particle flow theory and PFC2D software. In the rock slope model, the rock block and joint were represented by bonded-particle model and smooth-joint model, respectively. The main research results are as follows: (1) Due to orientation and discontinuities of joint, the sliding shape at the bottom of the sliding mass is relatively straight, while the tailing edge shape of sliding mass is flexural and is presenting step-path failure. (2) The fragmented particle assemblies of sliding mass are primarily generated in the middle and bottom part of slope. And they are subsequently generated in the top part of slope. The bulk of fragmented particle assemblies in the middle and bottom part are relatively larger than those in the top part. (3) At the end of sliding process, the contact force of particle is relatively larger along with the direction of rock bridge, and the effect of stress arch is generated around the primary joints. (4) During the sliding process of rock slope, the relationship between the magnitude and count of microseismic events obeys the normal distribution function approximately

Evaluation of Soil Properties, Topographic Metrics, Plant Height, and Unmanned Aerial Vehicle Multispectral Imagery Using Machine Learning Methods to Estimate Canopy Nitrogen Weight in Corn

Management of nitrogen (N) fertilizers is an important agricultural practice and field of research to minimize environmental impacts and the cost of production. To apply N fertilizer at the right rate, time, and place depends on the crop type, desired yield, and field conditions. The objective of this study is to use Unmanned Aerial Vehicle (UAV) multispectral imagery, vegetation indices (VI), crop height, field topographic metrics, and soil properties to predict canopy nitrogen weight (g/m2) of a corn field in southwestern Ontario, Canada. Random Forests (RF) and support vector regression (SVR) models were evaluated for canopy nitrogen weight prediction from 29 variables. RF consistently had better performance than SVR, and the top-performing validation model was RF using 15 selected height, spectral, and topographic variables with an R2 of 0.73 and Root Mean Square Error (RMSE) of 2.21 g/m2. Of the model’s 15 variables, crop height was the most important predictor, followed by 10 VIs, three MicaSense band reflectance mosaics (blue, red, and green), and topographic profile curvature. The model information can be used to improve field nitrogen prediction, leading to more effective and efficient N fertilizer management

Sports and Chinese herbal medicine

Background: Chinese herbs have been used in sports and exercises as potent remedies for the treatment of sports injuries and recovery from sports fatigue. Herbs such as Astragalus, Radix Codonopsis, Shiitake and Rhodiola are favoured for their ability to help athletes improve their physical performance and to enable rapid recovery from fatigue. Abundant studies have proved that these traditional Chinese medicines(TCM) have a positive effect on athletic performance. For instance, TCM have been shown to have a significant recovery effect on skeletal muscle, cardiovascular and central nervous system fatigue caused by sports training or intense competition. Admittedly, it is necessary for more in-depth research to ensure the safety of TCM in sports. However, relatively little research has been done in this area and more studies are needed to assess and confirm the effects of TCM on the post-exercise organism, particularly with regard to the dosage of TCM, the duration of supplementation and a larger sample size. Purpose: The main purpose of the research is to restore athletes' athletic fatigue and improve their athletic performance through traditional Chinese medicine, changing the traditional massage method to restore fatigue. By looking for literature, the achievements of predecessors are summarized and summarized. Methods: I reviewed the literature of many scholars on Chinese medicine, described the value and potential of Chinese medicine in sports, and put forward a new research direction on Chinese medicine and sports Results: the results of scholars have shown that the fatigue recovery of athletes can be improved through traditional Chinese medicine, and the performance of athletes can be improved to a certain extent. Conclusion: The conclusion is that the conditioning through traditional Chinese medicine can promote the athletic performance of athletes, while improving their physiology and restoring fatigue to a certain extent

Comparative research on vapor injection heat pump with a novel flash tank

Two major problems for the vapor injection heat pump systems with the flash tank are the high discharge temperature and the lack of flash tank design theoretical basis, which would limit its wide application in extreme operating conditions. One possible way to overcome these problems is to effectively control the two-phase injection in the flash tank by optimizing its structure. The use of the proposed novel flash tank in the quasi-two-stage vapor injection cycle represents an economic and controllable solution. This research experimentally analyzes the influences of flash tank structure and volume on the system heating performance under different compressor frequencies and injection pressures at the ambient temperature of −10 °C. The comparative analysis is done finding that the novel flash tank could maximumly improve the system Coefficient of Performance (COPh) by 6.4% in this test, compared with the traditional type A flash tank cycle. In the meanwhile, a bad design of novel flash tank size could represent a loss of COPh improvement between 5.73% and 13.5%. Due to the particular structure, the implementation of the novel flash tank also allows the injection mass flow ratio can keep a linear relationship with the injection pressure. Moreover, the refrigerant liquid can be regularly injected into the compression chamber to control discharge temperature under 100 °C. From all the analysis, guidelines for optimizing the control strategy and the flash tank design are put forward, which can be used to perfect the real thermodynamic model of the flash tank rather than the ideal two-phase separation model

Acoustic Nonlinearity of Liquid Containing Encapsulated Microbubbles

Abstract An approach to describe the acoustic nonlinearity of the liquid containing encapsulated microbubbles is presented. The nonlinear wave equation for such liquid is derived and the second harmonic generation, the attenuation of fundamental harmonic and equivalent acoustic nonlinearity parameter (B/A) e are studied. Numerical calculations for a contrast agent, Albunex ® , show that there is a good agreement between our theory and Wu's experiment

Ticket Allocation Optimization of Fuxing Train Based on Overcrowding Control: An Empirical Study from China

At the peak of passenger flow, some passengers extend travel sections, which will be likely to lead to overcrowding of high-speed railway (HSR) trains. Therefore, the problem of train overcrowding control needs to be considered in ticket allocation. Firstly, by simulating the passenger demand function and utility function, an optimization model of ticket allocation for multiple trains and multiple stops with the goal of maximizing revenue is constructed. Secondly, the concepts of the travel extension coefficient and risk coefficient are introduced, the number of passengers is estimated under the risk coefficient as the probability, and the total number of passengers on the train arriving at any station is obtained. Thus, preventing the number of passengers on the train from exceeding the train capacity is introduced to the ticket allocation optimization model of multiple trains and multiple stops as a constraint. Finally, this model is solved by the particle swarm optimization algorithm (PSO). The research results show that the idea of controlling passenger numbers so as not to exceed train capacity based on ticket allocation proposed in this paper has strong practical feasibility. By reasonably and accurately allocating the tickets to the departure terminal section and long-distance terminal sections, it can ensure that, even if there are some passengers extending their travel section, the train will not be overcrowded under a certain probability, improving the train safety and passenger travel experiences

Residual Stress Properties of the Welded Thick Underwater Spherical Pressure Hull Based on Finite Element Analysis

Residual stress inevitably occurs at the weld in the process of manufacturing thick pressure hulls for manned submersibles, which affects the bearing capacity of the hull. In this study, an electron-beam-welded 32 mm-thick Ti-6Al-4V plate specimen is first tested, then the measured data of residual stress distribution is applied to validate the accuracy of the simulation method. Accordingly, three-dimensional numerical analysis on the equator welding by electron beam method of a 32 mm-thick Ti-6Al-4V spherical pressure hull is conducted to obtain the variation tendency of residual stress during the welding process. The results indicate that both compressive and tensile stresses exist along the weld path on the outer surface of the hull comparing to total tensile stresses on the inner surface. The maximum tensile stress that occurs on the inner surface approximates to 850 MPa, which is almost equivalent to the yield stress of the material. Based on the acceptance criterion that the peak value of residual stress due to weld technique is restricted to be less than 40% of the material yield strength in room temperature, post-weld heat treatment must be performed. Simulation on post-weld heat treatment for optimizing process parameters can be done by taking the results of welding simulation in the present study as input