481 research outputs found
Atomization and droplet dynamics of a gas-liquid two-phase jet under different mass loading ratios
No full textAtomization and droplet dynamics of a gas-liquid two-phase jet were investigated experimentally, with the particular interest in the influence of mass loading ratio (the ratio of droplet mass flow rate to the carrier-phase mass flow rate, ranging from 0.60 to 3.23) on the jet atomization. Droplet size and velocity at selected positions were obtained by employing Phase Doppler Particle Analyzer (PDPA), combined with backlit illumination for spray visualization. Droplet transport characteristics are substantially influenced by the mass load ratio. Char-acterization of the local gas flow velocity by using droplets smaller than 5 mu m reveals a highly turbulent jet with Reynolds number exceeding 5 x 10(4), implying the possibility of droplet turbulent breakup. Critical equilibrium location x(crit )between droplet breakup and coalescence is close to the nozzle exit and a positive correlation is found between mass loading ratio and x(crit). Exaltation of mass loading ratio increases the droplet size and de-creases the velocity. Quantification of droplet collision outcome indicates a relatively high probability of coa-lescence, which explicates the downstream increasing of measured droplet Sauter mean diameter along the centerline of far-field jet
Dascillus mongolicus Heyden 1889
No full textDascillus mongolicus Heyden, 1889 Specimens examined: Hubei Province, Shennongjia, Dajiu Lake, 10-vi-1977, Leyi Zhen leg. (1♀, NKUM); Hubei Province, Shennongjia, Dayawu, 5-vi-1977, Huanguang Zou leg. (2 ♂♂, 1 ♀, NKUM); Hubei Province, Shennongjia, Dayawu, Hubei, 26-vi-1977, Leyi Zhen leg. (1 ♂, NKUM); Hubei Province, Shennongjia, Dayawu, 27-vi-1977, Qiang Mu leg. (1♂, 1 ♀, NKUM); Hubei Province, Shennongjia, Hongping, 5-vi-1977, Huanguang Zou leg. (1 ♀, NKUM); Hubei Province, Shennongjia, Songbai, 30-vi-1977, Qiang Mu leg. (1 ♀, NKUM); Xizang, Chayu County, Chawalong, 1950 m, 2-vii-2005, Aiming Shi leg. (1 ♀, MHBU); Xizang, Chayu County, Menkong, 2400–3000 m, 4-vii-2005, Aiming Shi leg. (1 ♂, MHBU). General distribution: China (Gansu, Henan, Hubei, Ningxia, Shaanxi, Sichuan, Xizang, Yunnan).Published as part of Jin, Zhenyu, Qin, Zhao & Ślipiński, Adam, 2018, New records of the family Dascillidae (Coleoptera) from China, pp. 396-400 in Zootaxa 4471 (2) on page 398, DOI: 10.11646/zootaxa.4471.2.13, http://zenodo.org/record/143964
Deterioration mechanism of adhesion properties of FRP-soil interface induced by moisture
No full textThe deterioration of FRP-soil interfacial adhesion due to water intrusion has been a core issue in geotechnical engineering, but its microscopic mechanism remains unclear. In this study, molecular dynamics (MD) simulation method is employed to reveal the microscopic deterioration mechanism of water on adhesion properties of epoxy-quartz (i.e., FRP-soil subsystem) interface, the structural and dynamic characteristics of interlayer water film. The steered molecular dynamics (SMD) pulling simulation and the modified Bell’s model are used to evaluate the adhesion energy of epoxy-quartz interface in dry and wet cases. The simulation results show that (1) the interfacial water film weakens adhesion strength of epoxy-quartz interface, playing a dual role in “interface isolation” and “lubrication”, aggravating the interfacial debonding. (2) The work of adhesion, maximum pulling force, PMF, and adhesion energy of dry system are significantly higher than those of wet system. (3) The interlayer water film has a distinct layered structure: bound, free, and sparse water layers, which have different angle orientations and density distributions. (4) The diffusion coefficient increases with the rising thickness of free water layer, which may trigger a capillary-seepage effect and aggravate interface deterioration. This study provides atomic-scale insights into moisture-induced FRP-soil interface failure mechanism.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Interaction between Virtual and Reality: Real-Time Collision Detection for UAVs in VR scenario
No full textAbstractRobot swarm experiments in laboratory scenarios are often constrained by the limitations of the experimental site, and researchers always suffer from many problems such as the small experimental space, the difficulty of matching the obstacles in the experiments with those in real scenarios, and the difficulty of simulating specific environments in the laboratory. Based on this background, the author has constructed a virtual-reality collision detection feedback experiment platform for UAVs in the laboratory under the guidance. The platform is based on a motion capture system [1] as well as the ROS system [2], and is able to provide real-time feedback on the collision between a flying real UAV and an obstacle in the virtual environment with a low latency time. The author\u27s experiments are divided into two major sections. In the first section, the author focuses on familiarizing the operating principle of the motion capture system and the ROS system and sets up a collision feedback model with extremely high speed although sacrificing some accuracy. This part of the approach draws on the ideas of the AABB algorithm [3] [4], with the prior import and loading of the obstacle map, to be able to respond to the data release frequency of more than 1000Hz. In this process, the author also created a program module used to simulate the data distribution module of the motion capture system and visualize experimental results. The focus of this part of the work is to familiarize the author with the experimental tools such as the Optitrack system, as well as the ROS system, meanwhile to verify the feasibility of the experimental design ideas. The goal of the second section is to optimize the model from the first section further. In this section, the author further enhances the accuracy of the collision detection model without introducing too much time complexity. Before conducting the experiments in this section, the author reviewed some papers and chose to use the OBB algorithm [4], GJK algorithm [5], and attitude solver [6] to accurately determine the collision between the volume of a real UAV and the volume of a virtual obstacle, no matter how complex the shape of the UAV and the obstacle is [4] [7]. And while the accuracy is significantly improved, the response data release frequency can still be stable up to 500Hz-1000Hz. At the end of the experiment, the author visualizes the experimental results and gives an outlook on future research
Characterization and functional studies of electrospun/sprayed complexes loaded with phytochemicals
No full textAt the era of high civilization, people are facing elevating amount of negative environmental impacts like polluted air or water, increased UV irradiation, carcinogens and many more. These impacts may lead to accumulation of oxidative stresses in our body which further trigger inflammations and even cancers. Fortunately, researchers found many bioactive phytochemicals could act against these oxidative stresses thus achieve multiple health benefits. However, many of them are not stable, prone to oxidation and heat during storage or productions. Besides, a large number of them have problems in water solubility and absorption. In order to overcome these barriers, various types of delivery systems are developed to encapsulate and protect the phytochemicals, to increase their solubility, bioaccessibility and bioavailability. Nano emulsions may be the most popular delivery systems and are able to significantly increase the solubility of beneficial phytochemicals. Nevertheless, they also came with some disadvantages like emulsion breakage, low encapsulation efficiency, etc. Besides, production of nano emulsion also require large amount of mechanical energy input like high pressure homogenization. Addition of preservatives to the nano emulsions also caused some health concerns. In this research, a novel lipid delivery system called electrosprayed lipid-polymer complex (ELPC) was established. ELPC was fabricated by electrospinning technique for atomizing phytochemicals and other formulation components without high energy consumption or generating noticeable heat. Unlike most of the routine electrospinning process, ELPC was prepared without toxic organic solvents or components that was highly applicable in the real world. More importantly, ELPCs are able to generate self- assembled emulsions when they are in contact with water. Since the ELPCs could be stored in dry condition and able to generate emulsions at the moment of application, they are immune to environmental impacts like ambient temperature fluctuation, physical shocks or bacterial contamination that are fatal to routine emulsions. ELPC was substantiated to achieve effective topical skin delivery of water-insoluble phytochemicals with the ability of anti-oxidation and tyrosinase inhibition, which was quantified by Franz-cell diffusion and visualized by confocal laser microscopy. The self-assembled nano emulsions generated from ELPCs have mean diameters around 300-400 nm by measured by dynamic light scattering. Cellular uptake of phytochemical loaded ELPC emulsion was proven effective against B16F10 melanoma cells. In addition, ELPC could also be adopted as an effective oral delivery system for phytochemicals. Digestion profile and characteristics of the edible ELPC was examined by USP-4 dissolution tester and an in vitro lipolysis assay, which had indicated successful digestion of the ELPC system and improved release of phytochemical comparing to the control. Afterwards, a Caco-2 monolayer membrane transport assay was carried out and proved effective transport of phytochemicals from the digested ELPC through the artificial intestinal monolayer to be able to enter the blood stream.Ph.D.Includes bibliographical referencesby Zhenyu Li
Activated TiO2 with tuned vacancy for efficient electrochemical nitrogen reduction
No full textRenewable energy-driven electrochemical N-2 reduction reaction (NRR) provides a green and sustainable route for NH3 synthesis under ambient conditions but is plagued by a high reaction barrier and low selectivity. To promote NRR, modification of the catalyst surface to increase N-2 adsorption and activation is key. Here, we show that engineering surface oxygen vacancies of TiO2 permits significantly enhanced NRR activity with an NH3 yield rate of about 3.0 mu g(NH3)h(-)(1 )mg(cat.)(-1) and a faradaic efficiency (FE) of 6.5% at -0.12 V (vs. the reversible hydrogen electrode, RHE). Efficient conversion of N-2 to NH3 is achieved in a wide applied potential range from -0.07 to -0.22 V (vs. RHE) with NH3 production rates >= 2.0 RgNH(3 )mu g(NH3)h(-)(1 )mg(cat.)(-1) and NH3 FEs >= 4.9%, respec- tively. An NH3 FE as high as 9.8% is obtained at a low overpotential of 80 mV. Density functional theory calculations reveal that the surface oxygen vacancies in TiO2 play a vital role in facilitating electrochemical N-2 reduction by activating the first protonation step and also increasing N-2 chemisorption (relative to *H).
Optimally integrating a reservoirs group and a flood detention basin for improving their flood control performance
No full textJingjiang flood detention basin and Three gorges (TG), Shuibuya (SBY) and Geheyan (GHY) reservoirs are located in the midstream and downstream of Changjiang River Basin. These reservoirs as a group and the flood detention basin are crucial to mitigate the extreme magnitude flood events in the midstream and downstream of Changjiang River Basin. This study proposed an optimal model to integrate the operation of a reservoirs group and flood detention basin rather than the current separately operations for improving their flood control performance. The operation schemes of an FDB sluices are enumerated for exploring the potential start time and end time of operating an FDB. The regulation of a reservoirs group is integrated with the operation of the sluices of an FDB. The impacts of the optimal FDB and reservoirs group flood control schemes on the flood control performance are quantified to gain insights on the difference between the FDB and reservoirs group flood control. The results and discussion indicate that synchronizing the operation of an FDB sluice-gate for the flood peak is better than the traditional rule for reducing the over flood volume. And the more flexible FDB flood control scheme can significantly improve the flood control performance. Therefore, our study will not only propose an optimal model to integrate an FDB and a reservoirs group, but also help to comprehend the mechanism of the reservoirs group and FDB flood control. [Display omitted]. A model to integrate a flood detention basin (FDB) and reservoirs is proposed for improving flood control performance. The impacts of FDB on flood control are quantified to understand the difference between FDB and reservoir flood control. The ways of operating FDB affect flood control performance are explored
MoS2 nanosheets supported on hollow carbon spheres as efficient catalysts for electrochemical hydrogen evolution reaction
No full textHybridizing structured carbon materials with MoS2 has
been demonstrated to be an effective method to increase the
electrochemical hydrogen evolution reaction (HER) activity and
durability of MoS2. In this study, we report the growth of MoS2
nanosheets on the surface of uniform hollow carbon spheres (HCS) to
form a hydrangea-like nanocomposite. The HCS were formed through
carbonization of a phenol formaldehyde template, and the MoS2
nanosheets were grown on the HCS surfaces through a hydrothermal
method. The nanocomposites have the advantages of significantly
improved electrical conductivity, ease of varying the MoS2 loading, and
minimizing stacking of MoS2 nanosheets, which are manifested by their
remarkably improved HER performance. The well-tuned carbon−MoS2
composite shows a Tafel slope of 48.9 mV dec−1, an onset potential of
−0.079 V (vs reversible hydrogen electrode), and an overpotential of 126
mV at the current density of 10 mA cm−2 after 1000 potential cycles
A general chopping peak function for a reservoirs group flood control regulating
No full textFlood event is one of the natural hazards and has affected the most people in the world. As the peak of the flood event is the most striking feature to its hazard, chopping flood peak is often the main goal of preventing flood hazard. To integrate the regulation of the flood storages in a reservoirs group for chopping flood peak, a general relationship among the flood events, the flood storages and the chopping peak has been quantified through Chopping Peak Function (CPF). And we have derived the analytical solutions for a single, a parallel or a cascade reservoirs group while numerical solution for a mixed reservoirs group to their corresponding CPF. Based on the solutions to their CPF, the mechanism is clarified for the integrated reservoirs flood storages regulation. The derived analytical solutions have also been proven to be more efficient for integrating the reservoirs regulation than for only every single reservoir regulation. The numerical solutions for the mixed reservoirs groups are found to be better than that of optimal reservoirs regulation model through NSGA-II in terms of the number and the distribution range of the Pareto frontier. Therefore, our study will not only help understand the regulation of the f lood storages in reservoirs groups for chopping flood peak, but also find an efficient way to prevent flood hazard
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