Particle flux through the Huanghai Sea cold water mass

Settling particulate matter （SPM） was collected by using sediment traps at four stations in a survey section from Qingdao to Cheju-do, across the Huanghai Sea cold water mass （HSCWM）, in August 2002. The sediment traps were planted in three layers： the upper layer of the thermocline （ULT） above the HSCWM, the lower layer of the thermocline （LLT）, and the bottom layer of water column （BL）. To determine the particle flux, the contents of organic carbon （POC）, organic nitrogen （PON）, total carbon （PC）, and total phosphorous （PP） in SPM were analyzed, and two flux models （Ⅰ and Ⅱ） were improved to calculate the resuspension ratio, with an assumption in Model Ⅰ that the vertical flux of SPM in the LLT equals the net vertical flux of SPM in the whole water column. An X value, i.e., the fraction of the resuspension flux originating from the surficial sediments nearby the sampling station, was deduced from Model Ⅰ to estimate the contribution of lateral currents to the total resuspension flux. The results showed that inorganic particles, fecal pellets, and miscellaneous aggregates were the major types of SPM in the HSCWM, and the contents of POC, PON, PC, and PP all decreased with water depth. A great deal of fecal pellets found in the LLT indicates that the main space producing biogenic SPM is the thermocline, and especially the LLT, where the C/N ratio is lower than that in the ULT. The resuspension ratios, 90%-96% among stations, imply strong impact ofresuspension on particle flux in the BL. These values were not significantly different between the two flux models, suggesting that the hypothesis in Model Ⅰ that the flux in the LLT equaling the net flux to the bottom is acceptable for shallow waters with stratification like the HSCWM. The POC export ratio from the HSCWM ranges from 35% to 68%. It benefits from the short sinking distance in shallow water. The upwelling in the HSCWM enhanced the POC flux through the water mass, and the lateral currents provides up to being greater than 50% ofresuspension flux in the BL according to evaluation of the X value.

Measurement of neutron and charged particle fluxes toward earthquake prediction

In this paper, we describe a possible method for predicting the earthquakes, which is based on simultaneous recording of the intensity of fluxes of neutrons and charged particles by detectors, commonly used in nuclear physics. These low-energy particles originate from radioactive nuclear processes in the Earth＇s crust. The variations in the particle flux intensity can be the precursor of the earth- quake. A description is given of an electronic installation that records the fluxes of charged particles in the radial direction, which are a possible response to the accumulated tectonic stresses in the Earth＇s crust. The obtained results showed an increase in the intensity of the fluxes for 10 or more hours before the occurrence of the earthquake. The previous version of the installation was able to indicate for the possibility of an earthquake （Maksudov et al. in Instrum Exp Tech 58：130-131, 2015）, but did not give information about the direction of the epicenter location. In this regard, the installation was modified by adding eight directional detectors. With the upgraded setup, we have received both the predictive signals, and signals determining the directions of the location of the forthcoming earthquake, starting 2-3 days before its origin.

Bursty Behaviour of Turbulent Particle and Energy Fluxes in Edge Plasma of HT-7 Tokamak

High time resolution measurements of the electrostatic fluctuations and the turbulent particle and energy fluxes have been performed with a Langmuir probe array in the edge plasma in HT-7 tokamak. Bursty behaviour was observed in the time resolved turbulent fluxes with positive skewness and large kurtosis. The contribution of the large sporadic bursts to the transport losses were estimated. The analysis shows that the turbulent fluxes have different behaviour in different frequency domains and the probability distribution functions （PDFs） of the particle and energy fluxes present two distinct scaling ranges. All these are essentially consistent with the predictions of the self-organized criticality （SOC） model, though further studies are needed.

A novel optical emission spectroscopy method for diagnostics of contribution of different ionization mechanisms and flux of ions in different valences in discharge channel of a Hall thruster

The mass application of Hall thrusters poses the need for a diagnostic method of ionization mechanism in the discharge channel to boost the iteration and optimization of thruster design.This work presents an Optical Emission Spectroscopy (OES) method for diagnostics of the contribution of different ionization mechanisms and the flux of ions in different valences in the discharge channel of a Hall thruster.The emission spectra in the discharge channel are analyzed by jointly utilizing a collisional-radiative model,an ionization-excitation model,and a flux-conservation model.It is found that the intensities of some spectral lines can be converted into the reaction rates of collision processes,e.g.,electron-induced excitation and ionization processes.The latter can further be used to determine the evolutions of particle fluxes by utilizing the conservation law of matter.The novel method is demonstrated on a kilo-watt Hall thruster.The evolutions of several parameters are determined using this method along the discharge channel,including the ionization rates of different mechanisms,particle fluxes,particle densities,and particle velocities.This novel method can be further developed by being jointly utilized with spectral imaging and tomography techniques,enabling diagnostics of multi-dimensional distributions of the above-mentioned parameters in the discharge channel and near-field plume.

Multi-scale interaction between tearing modes and micro-turbulence in the HL-2A plasmas

The influence of m/n=2/1(m and n are poloidal and toroidal mode numbers)tearing modes on plasma perpendicular flows and micro-fluctuations has been investigated in HL-2A neutral beam injection heated L-mode plasmas.It is found that the local perpendicular rotation velocity and turbulence energy are modulated by the alternation between the island X-point and O-point of the naturally rotating tearing modes.Cross-correlation analysis indicates that the modulation of density fluctuations by the tearing mode is not only limited to the island region,but also occurs in the edge region near the last closed flux surface.The turbulence exhibits distinct spectral characteristics inside and outside the island region.In addition,it is observed that the particle flux near the strike point is also significantly impacted by the tearing modes.The experimental evidence reveals that there are strong core-edge interactions between the core tearing modes and the edge transport.

Energetic particles’fluxes and dose in the Radiation Gene Box measured by space radiation detector onboard SJ-10 satellite

Background To evaluate the hazard of space radiation posing to the tissues,it is important to obtain exact fluxes of different radiation particles.The Radiation Gene Box(RGB)onboard SJ-10 spacecraft was an instrument designed to investigate the effects of space environment on the mESCs and drosophila.To derive the dose received by the tissues inside the RGB,the Space Radiation Detector(SRD)was installed inside it.Purpose The SRD was designed to derive the fluxes of electron,proton,hellion and gamma rays around it.If the type of the particles,the energies,the fluxes and the conversion coefficients are known,the dose received by the tissues could be evaluated.Methods The SRDwas designed as a △E-E solid-state telescope.By measuring the energy deposited in the three subdetectors,the particles’type and their energies could be discriminated.The data of SRDwere divided into 15 bins by the types of particles and their energy ranges.Results The gamma ray flux was higher than any other particle flux inside the RGB,and the electron was the most intense charge particle,while the helium ion was the most harmful radiation to the cells inside the RGB.Conclusion The dose rate inside the Radiation Gene Box was much higher than in the ground,but the integral dose of 12 days inside the RGB was about 2.13 mSv.It seemed unlikely to have obvious biological effects on the tissues of mice and drosophila.

Gas-solid flow in a high-density circulating fluidized bed riser with Geldart group B particles

We carried out experiments to explore and characterize the gas-solid flow dynamics of Geldart group B particles in a dense circulating fluidized bed riser. By reducing the pressure drop across the solid control valve and increasing the solid inventory in the storage tank, a high solid circulation rate and a solid holdup above 0.075 throughout the riser were simultaneously achieved. At a solid-to-gas mass flux ratio of approximately 105, flow transitioned from fast fluidization to a dense suspension upflow. In the axial direction of the riser, solid holdup had an exponential profile, increasing with increasing solid circulation rate and Jot decreasing superficial gas velocity. From the riser＇s center to its wall, the solid holdup increased markedly, exhibiting a steep parabolic profile. Increasing the solid circulation rate increased the radial non-uniformity of the solid concentration, while increasing the superficial gas velocity had the opposite effect, In our dense circulating fluidized bed riser, Geldart group B particles had similar slip characteristics to Geldart group A particles,

Two and three dimensional modeling of fluidized bed with multiple jets in a DEM-CFD framework

Fluidized beds with multiple jets have widespread industrial applications. The objective of this paper is to investigate the jet interactions and hydrodynamics of a fluidized bed with multiple jets. Discrete element modeling coupled with in-house CFD code GenlDLEST has been used to simulate a bed with nine jets. The results are compared with published experiments. Mono dispersed particles of size 550 ~m are used with 1.4 times the minimum fluidization velocity of the particles. Both two and three dimensional computations have been performed. To the best of our knowledge, the results presented in this paper are the first full 3D simulations of a fluidized bed performed with multiple jets. Discrepancies between the experiment and simulations are discussed in the context of the dimensionality of the simulations. The 2D solid fraction profile compares well with the experiment close to the distributor plate. At higher heights, the 2D simulation over-predicts the solid fraction profiles near the walls. The 3D simulation on the other hand is better able to capture the solid fraction profile higher up in the bed compared to that near the distributor plate. Similarly, the normalized particle velocities and the particle fluxes compare well with the experiment closer to the distributor plate for the 2D simulation and the freeboard for the 3D simulation, respectively. A lower expanded bed height is predicted in the 2D simulation compared to the 3D simulation and the experiment. The results obtained from DEM computations show that a 2D simulation can be used to capture essential jetting trends near the distributor plate regions, whereas a full scale 3D simulation is needed to capture the bubbles near the freeboard regions. These serve as validations for the experiment and help us understand the complex jet interaction and solid circulation patterns in a multiple jet fluidized bed system.