Microfluidic assisted 90%loading CL-20 spherical particles:Enhancing self-sustaining combustion performance

The performance of the chemical fuel determines the altitude,range and longevity of spacecraft in air and space exploration.Promising alternatives(e.g.,hypergolic ionic liquids or high-energy composites)with high-energy density,heat of formation and fast initial rate are considered as potential chemical fuels.As the high-energy density material,hexanitrohexaazaisowurtzitane(CL-20)often serves as secondary explosive with poor self-propagating combustion behaviors.Herein,90%loading CL-20 microspheres with uniform particle sizes are precisely prepared by microfluid method,which exhibit unique hierarchical structure.The morphology,thermal behaviors,as well as combustion performance were further investigated.The results demonstrated that as-prepared spherical particles exhibit prominent thermal compatibility,and the enhanced self-sustaining combustion performance.This work provides an efficient method achieving the uniform high-energy density particles with excellent self-sustaining combustion performance.

Impact of exterior electron emission on the self-sustaining margin of hollow cathode discharge

Hollow cathode researches used to focus on the inner cavity or downstream plume,however,rarely on the gap between the throttling orifice plate and the keeper plate(T-K gap),which was found to impact the self-sustaining margin of hollow cathode discharge in this paper.Near the lower margin,the main power deposition and electron emission and ionization regions would migrate from inner cavity and downstream plume to the T-K gap,in which case,the source and destination of each m A current therein matter for the self-sustaining capability.Changing the metal surfaces in the T-K gap with emissive materials proved effective in lowering the lower margin by supplementing auxiliary thermionic emission,compensating electron loss on cold absorbing walls and suppressing discharge oscillations.By doing so,the lower margin of a 4 A hollow cathode was lowered from 1 to 0.1-0.2 A,enabling it to couple with low power Hall thruster without extra keeper current.

Low energy consumption depth control method of self-sustaining intelligent buoy

Aiming at the contradiction between the depth control accuracy and the energy consumption of the self-sustaining intelligent buoy,a low energy consumption depth control method based on historical array for real-time geostrophic oceanography(Argo)data is proposed.As known from the buoy kinematic model,the volume of the external oil sac only depends on the density and temperature of seawater at hovering depth.Hence,we use historical Argo data to extract the fitting curves of density and temperature,and obtain the relationship between the hovering depth and the volume of the external oil sac.Genetic algorithm is used to carry out the optimal energy consumption motion planning for the depth control process,and the specific motion strategy of depth control process is obtained.Compared with dual closed-loop fuzzy PID control method and radial basis function(RBF)-PID method,the proposed method reduces energy consumption to 1/50 with the same accuracy.Finally,a hardware-in-the-loop simulation system was used to verify this method.When the error caused by fitting curves is not considered,the average error is 2.62 m,the energy consumption is 3.214×10^(4)J,and the error of energy consumption is only 0.65%.It shows the effectiveness and reliability of the method as well as the advantages of comprehensively considering the accuracy and energy consumption.

Supersonic boundary layer transition induced by self-sustaining dual jets

To promote high-speed boundary layer transition,this paper proposes an active self-sustaining dual jets(SDJ)actuator utilizing the energy of supersonic mainflow.Employing the nanoparticle-based planar laser scattering(NPLS),supersonic flat-plate boundary layer transition induced by SDJ is experimentally investigated in an Ma-2.95 low-turbulence wind tunnel.Streamwise and spanwise NPLS images are obtained to analyze fine flow structures of the whole transition process.The results reveal the transition control mechanisms that on the one hand,the jet-induced shear layer produces unstable Kelvin–Helmholtz instabilities in the wake flow,on the other hand,the jets also generates an adverse pressure gradient in the boundary layer and induce unstable streak structures,which gradually break down into turbulence downstream.The paper provides a new method for transition control of high-speed boundary layer,and have prospect both in theory and engineering application.

Tritium concentrations in precipitation in Shanghai

Tritium concentrations in precipitation can be used as a criterion to evaluate the tritium baseline of the environment. The tritium concentration in precipitation in Shanghai during 2014-2015 was determined. Values ranged from 0.68 ± 0.04 to 4.11 ± 0.39 Bq/L, and it showed a decreasing trend compared with historical data; however,the values were slightly higher than the natural background tritium level. Additionally, the tritium concentration shows a seasonal variation: It was higher in autumn and winter and lower in summer and spring. A comparison of concentrations in precipitation in Shanghai and around the Qinshan Nuclear Power Plant reveals no correlation,implying that the nuclear power plant operations may not affect the environment of Shanghai. Thus, the raised tritium concentrations in Shanghai might be due to the effects of monsoons, spring leak, raindrop, or other activities that generate tritium there. Those activities may include chemistry research that uses tritium as a tracer.

Simulation of the effects of different substrates, temperature,and substrate roughness on the mechanical properties of Al_2O_3 coating as tritium penetration barrier

Residual thermal stress in the system is a serious problem that affects the application of tritium permeation barrier coatings in fusion reactors. The stress not only determines the adhesion between coating and substrate, but also changes the properties of the material. In this study,finite element analysis was used to investigate the relationship between the residual thermal stress and the mechanical properties of Al_2O_3 tritium penetration barrier systems. Moreover, the residual thermal stress influenced by factors such as different substrates, temperature, and substrate roughness was also analyzed. The calculation showed that the hardness and elastic modulus increased with increasing compressive stress. However, the hardness and elastic modulus decreased with increasing tensile stress. The systems composed of Al_2O_3 coatings and different substrates exhibited different trends in mechanical properties. As the temperature increased, the hardness and the elastic modulus increased in an Al_2O_3/316 L stainless steel system; the trend was opposite in an Al_2O_3/Si system.Apart from this, the roughness of the substrate surface in the system could magnify the change in hardness and elastic modulus of the coating. Results showed that all these factors led to variation in the mechanical properties of Al_2O_3 tritium permeation barrier systems. Thus, thedetailed reasons for the changes in mechanical properties of these materials need to be analyzed.

Synthesis of Tritium and Deuterium Labelled Agmatine

An efficient procedure for the synthesis of agmatine labelled with tritium and deuterium is reported. The final tritiated product 4 was obtained with a specific activity of 40 Ci/mmol and a radiochemical purity of 95%.

Standardization of Tritium Water by TDCR Method

The triple-to-double coincidence ratio （TDCR） method of liquid scintillation count- ing is an absolute measurement method of radioactivity. The formulation of the TDCR method and the established TDCR liquid scintillation counter are presented in this paper. The NIST standard reference material （SRM） of tritium water was measured to verify the performance of the TDCR liquid scintillation counter.

Self-sustained Oscillation Pulsed Air Blowing System for Energy Saving

Currently, many studies have been made for years on dimensions of pneumatic nozzle, which influence the flow characteristic of blowing system. For the purpose of outputting the same blowing force, the supply pressure could be reduced by decreasing the ratio of length to diameter of nozzle. The friction between high speed air and pipe wall would be reduced if the nozzle is designed to be converging shape comparing with straight shape. But the volume flow and pressure, discussed in these studies, do not describe energy loss of the blowing system directly. Pneumatic power is an innovative principle to estimate pneumatic system’s energy consumption directly. Based on the above principle, a pulse blowing method is put forward for saving energy. A flow experiment is carried out, in which the high speed air flows from the pulse blowing system and continuous blowing system respectively to a plate with grease on top. Supply pressure and the volume of air used for removing the grease are measured to calculate energy consumption. From the experiment result, the pulse blowing system performs to conserve energy comparing with the continuous blowing system. The frequency and duty ratio of pulse flow influence the blowing characteristic. The pulse blowing system performs to be the most efficient at the specified frequency and duty ratio. Then a pneumatic self-oscillated method based on air operated valve is put forward to generate pulse flow. A simulation is made about dynamic modeling the air operated valve and calculating the motion of the valve core and output pressure. The simulation result verifies the system to be able to generate pulse flow, and predicts the key parameters of the frequency and duty ratio measured by experiment well. Finally, on the basis of simplifying and solution of the pulse blowing system’s mathematic model, the relationship between system’s frequency duty ratio and the dimensions of components is simply described with four algebraic equations. The system could be designed with specified frequency and duty ratio according to the four equations. This study provides theoretical basis for designing energy-saving air blowing system.

Electrolytic enrichment method for tritium determination in the Arctic Ocean using liquid scintillation counter

A method of measuring the tritium in seawater based on electrolytic enrichment and ultra-low background liquid scintillation counting techniques was established.The different factors influencing the detection limit were studied,including the counting time,the electrolytic volume of the seawater samples,the selection of background water,scintillation solution and their ratio.After optimizing the parameters and electrolyzing 350 mL volume of samples,the detection limit of the method was as low as 0.10 Bq/L.In order to test the optimization of system for this method,of the 84 seawater samples collected from the Arctic Ocean we measured,92%were above the detection limit(the activity of this samples ranged from 0.10 Bq/L to 1.44 Bq/L with an average of(0.30±0.24)Bq/L).In future research,if we need to accurately measure the tritium activity in samples,the volume of the electrolytic samples will be increased to further reduce the minimum detectable activity.

Levels and behavior of environmental tritium in East Asia

For a more systematic understanding of the levels of environmental tritium and its behavior in East Asia,a database on environmental tritium was established based on the literature published in the past 30 years.Subsequently,the levels and behavior of the environmental tritium were further studied by statistical analyses.The results indicate that the distribution of environmental tritium is inhomogeneous and complex.In areas without nuclear facilities,the level of environmental tritium has decreased to its background level,even though a certain number of atmospheric nuclear tests were performed before 1980.In general,the level of atmospheric tritium was marginally higher than the levels in precipitation and surface water;the levels in shallow groundwater and seawater were considerably lower.Furthermore,the levels of tritium in the atmosphere,precipitation,and inland surface water were strongly correlated with latitude and distance from the coastline.In soil and living organisms,the level of tissue-free water tritium(TFWT)was comparable to the tritium levels in local rainfall,whereas the persistence of organically bound tritium(OBT)in the majority of organisms resulted in an OBT/TFWT ratio greater than one.Conversely,extremely high levels of environmental tritium were observed near certain nuclear power plants and the Fukushima accident sites.These results highlight the requirement to know the tritium baseline level and its behavior in the environment beforehand to better assess the impact of tritium discharge.Further investigations of environmental tritium in East Asia using more efficient and adequate monitoring methods are also required.

Biodegradation of Tritium Labeled Polychlorinated Biphenyls (PCBS) by Local Salt Tolerant Mesophylic Bacillus Strains

Salt-resistant Bacillus strains, isolated from agricultural soils in Uzbekistan, were tested for degradation activity towards a mixture of polychlorinated biphenyls (PCBs) under aerobic conditions. The study employed the use of tritium labeled PCB congeners and traced the tritium label in cultures with high salt content. The experiments show that most of the selected strains were able to adsorb a part of the radioactivity, indicating transformation of the added PCBs. Gas chromatography demonstrated transformation of PCBs. The radioactive label was removed from several cultures by up to 91%, indicating also mineralization of PCBs. The study suggests that the isolated strains might be good candidates for the bioremediation of contaminated high-salt soils in Uzbekistan and other Central-Asian countries.

Investigation on hydrogen absorption/desorption properties of as-cast La(1-x)Mg_xNi4.25Al0.75(x=0.0, 0.1, 0.2, 0.3) alloys for tritium storage

La_((1-x))Mg_xNi_(4.25)Al_(0.75)(x = 0.0, 0.1, 0.2, 0.3)alloys for tritium storage were prepared by a method of electromagnetic induction melting. The crystal structure and hydrogen storage performance of the as-cast alloys were investigated. The results showed that a single phase of La Ni_4Al was in the alloys with x = 0.0 and 0.1 and that LaNi_4Al and second phase of(La,Mg)Ni)_3 and AlNi_3 were in the alloys with x = 0.2 and 0.3. On the other hand, the plateau pressures of P–C isotherms of the alloys were increased with the rise of the x value from 0.2 to 0.3 and the hydrogen storage capacity was obviously degraded simultaneously. It was found that the alloy had faster absorption kinetics as the proportion of Mg increased from 0.1 to 0.3.

Neutronic study on the effect of first wall material thickness on tritium production and material damage in a fusion reactor

In this study,the effects of changing first wall materials and their thicknesses on a reactor were investigated to determine the displacement per atom(DPA)and gas production(helium and hydrogen)in the first wall,as well as the tritium breeding ratio(TBR)in the coolant and tritium breeding zones.Therefore,the modeling of the magnetic fusion reactor was determined based on the blanket parameters of the International Thermonuclear Experimental Reactor(ITER).Stainless steel(SS 316 LNIG),Oxide Dispersion Strengthened Steel alloy(PM2000 ODS),and China low-activation martensitic steel(CLAM)were used as the first wall(FW)materials.Fluoride family molten salt materials(FLiBe,FLiNaBe,FLiPb)and lithium oxide(LiO_(2))were considered the coolant and tritium production material in the blanket,respectively.Neutron transport calculations were performed using the wellknown 3D code MCNP5 using the continuous-energy Monte Carlo method.The built-in continuous energy nuclear and atomic data libraries along with the Evaluated Nuclear Data file(ENDF)system(ENDF/B-V and ENDF/B-VI)were used.Additionally,the activity cross-section data library CLAW-IV was used to evaluate both the DPA values and gas production of the first wall(FW)materials.An interface computer program written in the FORTRAN 90 language to evaluate the MCNP5 outputs was developed for the fusion reactor blanket.The results indicated that the best TBR value was obtained for the use of the FLiPb coolant,whereas depending on the thickness,the first wall replacement period in terms of radiation damage to all materials was between 6 and 11 years.

Self-sustained target waves in excitable media with only a long-range link

In this paper we investigate spatiotemporal pattern formation in excitable media with only a long-range link. Besides the trivial solutions of spiral patterns, we find the asymptotic self-sustained target waves in the autonomous tissues. The wave source supporting this kind of new pattern is the oscillatory one-dimensional Winfree-loop self- organized under the presence of a long-range link, which is explored by the dominant phase-advanced driving method. Based on this understanding we can effectively regulate the oscillations of excitable media by suitably arranging the long-range link, including construction of self-sustained target waves with controllable period and wave length, or manipulation of system states between different patterns.

A Possible Minimum Toy Model with Negative Differential Capacitance for Self-sustained Current Oscillation

We generalize a simple model for superlattices to include the effect of differential capacitance. It is shown that the model always has a stable steady-state solution （SSS） if all differential capacitances are positive. On the other hand, when negative differential capacitance is included, the model can have no stable SSS and be in a self-sustained current oscillation behavior. Therefore, we find a possible minimum toy model with both negative differential resistance and negative differential capacitance which can include the phenomena of both self-sustained current oscillation and I-V oscillation of stable SSSs.

On the Energy Self-Sustainability of IoT via Distributed Compressed Sensing

This paper advocates the use of the distributed compressed sensing(DCS)paradigm to deploy energy harvesting(EH)Internet of Thing(IoT)devices for energy self-sustainability.We consider networks with signal/energy models that capture the fact that both the collected signals and the harvested energy of different devices can exhibit correlation.We provide theoretical analysis on the performance of both the classical compressive sensing(CS)approach and the proposed distributed CS(DCS)-based approach to data acquisition for EH IoT.Moreover,we perform an in-depth comparison of the proposed DCSbased approach against the distributed source coding(DSC)system.These performance characterizations and comparisons embody the effect of various system phenomena and parameters including signal correlation,EH correlation,network size,and energy availability level.Our results unveil that,the proposed approach offers significant increase in data gathering capability with respect to the CS-based approach,and offers a substantial reduction of the mean-squared error distortion with respect to the DSC system.

Estimating Hydrogeological Parameters in Covered Carbonate Rocks Using a Discrete-State Compartment Model and Environmental Tritium

Nowadays, isotope environmental technique tends to be used as a reconnaissance tool , both qualitative and quantitative, to calculate the aquifer parameters particularly in carbonate rock aquifers. But, the heterogeneous flow is still problematic when Lumped parameter Models are usually used to calculate the residence times and hydraulic parameters. However, Discrete State Compartment Model can provide a powerful model to heterogeneous medium. One such study was carried on in Dazha valley, where the environmental tritium was used as a tracer for determining hydrogeological parameters based on a discrete state compartment model

Analysis of tritium production in a 2 MW liquid-fueled molten salt experimental reactor and its environmental impact

Tritium release is one of the most concerning topics in nuclear power plants. Here, the tritium production in a 2 MW liquid-fueled molten salt experimental reactor(TMSR-LF1) was calculated by ORIGEN-S with an updated cross-section library generated by TRITON in SCALE 6.1.3 code system. The results show that the tritium production rate and normalized tritium production rate of TMSR-LF1 are 8.90x10^(11)Bq/day and4.45x10^(11)Bq/(MW day), respectively. The environmental impact of tritium was analyzed via PC-CREAM 08 with an assumed 36 % release rate of tritium referring to the molten salt reactor experiment. During normal operations, the maximum tritium concentration is 1.4 Bq/m^3 under normal condition, and the corresponding individual dose to the public is about 1 μSv/a; under extreme conditions, the maximum concentration and corresponding individual doses are 11.8 Bq/m^3 and 9 μSv/a, respectively.Ingestion is the main exposure pathway and accounts for62 % of the total dose. Of this, 35 % is from organically bound tritium.

Development of a novel system for monitoring tritium in gaseous form

Tritium real-time measurement in glovebox or workplace is important to ensure safe operation of tritium. A novel tritium monitor system including an open-walled ionization chamber, an electrometer and an IPC(Industrial Personal Computer) has been developed to measure tritium in gaseous form. Using mesh walls, instead of sealed wall, the open-walled ionization chamber has less tritium absorption and lower memory effect. In addition, tritium gas can diffuse into the chamber's sensitive region without the assistant of sampling system and ion trap, which are installed at the front-end of commonly used flow-through ionization chambers. Background signal of this monitor system is about 3.7 × 105Bq/m3, and after exposed to tritium concentration at about 1011Bq/m3 for 4h, background of the monitor can recover after purging it several times with dry air. It is suitable for longtime tritium measurements in both glovebox and workplace.