41,597 research outputs found
Effects of turbulent dust grain motion to interstellar chemistry
Theoretical studies have revealed that dust grains are usually moving fast
through the turbulent interstellar gas, which could have significant effects
upon interstellar chemistry by modifying grain accretion. This effect is
investigated in this work on the basis of numerical gas-grain chemical
modeling. Major features of the grain motion effect in the typical environment
of dark clouds (DC) can be summarised as follows: 1) decrease of gas-phase
(both neutral and ionic) abundances and increase of surface abundances by up to
2-3 orders of magnitude; 2) shifts of the existing chemical jumps to earlier
evolution ages for gas-phase species and to later ages for surface species by
factors of about ten; 3) a few exceptional cases in which some species turn out
to be insensitive to this effect and some other species can show opposite
behaviors too. These effects usually begin to emerge from a typical DC model
age of about 10^5 yr. The grain motion in a typical cold neutral medium (CNM)
can help overcome the Coulomb repulsive barrier to enable effective accretion
of cations onto positively charged grains. As a result, the grain motion
greatly enhances the abundances of some gas-phase and surface species by
factors up to 2-6 or more orders of magnitude in the CNM model. The grain
motion effect in a typical molecular cloud (MC) is intermediate between that of
the DC and CNM models, but with weaker strength. The grain motion is found to
be important to consider in chemical simulations of typical interstellar
medium.Comment: 20 pages, 10 figures and 2 table
Giant magnetoimpedance in crystalline Mumetal
We studied giant magnetoimpedance (GMI) effect in commercial crystalline
Mumetal, with the emphasis to sample thickness dependence and annealing
effects. By using appropriate heat treatment one can achieve GMI ratios as high
as 310%, and field sensitivity of about 20%/Oe, which is comparable to the best
GMI characteristics obtained for amorphous and nanocrystalline soft magnetic
materials.Comment: 8 pages, 3 figure
Transmutation prospect of long-lived nuclear waste induced by high-charge electron beam from laser plasma accelerator
Photo-transmutation of long-lived nuclear waste induced by high-charge
relativistic electron beam (e-beam) from laser plasma accelerator is
demonstrated. Collimated relativistic e-beam with a high charge of
approximately 100 nC is produced from high-intensity laser interaction with
near-critical-density (NCD) plasma. Such e-beam impinges on a high-Z convertor
and then radiates energetic bremsstrahlung photons with flux approaching
10^{11} per laser shot. Taking long-lived radionuclide ^{126}Sn as an example,
the resulting transmutation reaction yield is the order of 10^{9} per laser
shot, which is two orders of magnitude higher than obtained from previous
studies. It is found that at lower densities, tightly focused laser irradiating
relatively longer NCD plasmas can effectively enhance the transmutation
efficiency. Furthermore, the photo-transmutation is generalized by considering
mixed-nuclide waste samples, which suggests that the laser-accelerated
high-charge e-beam could be an efficient tool to transmute long-lived nuclear
waste.Comment: 13 pages, 8 figures, it has been submitted to Physics of Plasm
Experience of producing natural gas from corn straw in China
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Globally, crop straw is a rich resource and further establishment of its use as an energy source is an important aspect in developing the circular economy. Projects in this vein can bring benefits such as improving energy access and living conditions as well as boosting the local economy and employment opportunities in rural communities. This paper presents a detailed case study on the production of bio-natural gas (BNG) from corn straw in China, using Life Cycle Analysis (LCA) to assess energy consumption and greenhouse gas (GHG) emissions, conducting economic analysis, and analyzing operation management models. The "Nongbaomu" business model (whereby professional personnel assist farmers in the management of straw collection, bundling, storage and transportation) and the "Mutual Offsetting in Kind" business model (whereby farmers can buy a quota of the project's BNG products at a lower price in return for selling straw to the project) can ensure the acquisition of straw by the BNG project at stable prices and high quality. Because the main product (BNG) replaces refined oil products used by automobiles and the byproduct (organic fertilizer) replaces traditional fertilizer (produced using coal), the project offers the potential for significant decreases (up to 80%) in life cycle GHG emissions and fossil fuel use. Benefited from the relatively high natural gas prices in the project location and applicable government subsidies, our studied case was found to be economically viable. The findings in this study are also likely to be relevant to other countries where governments should develop industrial policies that support the development of rural distributed energy, and introduce and implement appropriate subsidies to allow BNG to compete in the traditional natural gas market. Although, enterprises are responsible for selecting an effective business models and the most appropriate technological pathway, governments should also identify the ways in which they can support businesses to make these choices.This project was co-sponsored by the National Natural Science Foundation of China (71774095, 71690244 and 71673165) and International Science & Technology Cooperation Program of China (2016YFE0102200)
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