Zhang X, Ma S, Zhang Y, Zhang L, Gao W. Nonlocal Edge-Directed Interpolation, in Advances in Multimedia Information Processing - PCM 2009, 10th Pacific Rim Conference on Multimedia, Bangkok, Thailand, December 15-18, 2009 Proceedings.; 2009:1197–1207. 访问链接
This paper reports that Coulomb explosions taken place in the experiment of heteronuclear deuterated methane clusters ((CD4)2) in a gas jet subjected to intense femtosecond laser pulses (170mJ, 70fs) have led to table-top laser driven DD nuclear fusion. The clusters produced in supersonic expansion had an average size of about 5nm in radius and the laser intensity used was 3×1017W/cm2.The measured maximum and average energies of deuterons produced in the laser--cluster interaction were 60 and 13.5keV, respectively. From DD collisions of energetic deuterons, a yield of 2.5(±0.4)×104 fusion neutrons of 2.45MeV per shot was realized, giving rise to a neutron production efficiency of about 1.5×105 per joule of incident laser pulse energy. Theoretical calculations were performed and a fairly good agreement of the calculated neutron yield with that obtained from the present experiment was found.
Simplicity of mesh generation and robustness against mesh entanglement during large deformations are key attractive features of particle based methods. These features can be exploited in number of engineering problems where traditional techniques suffer due to aforementioned limitations. Numerical modelling of particulate composites is one of such ideal engineering applications where particle based methods can be effectively used due to their simplicity and robustness. Complicated geometrical configurations of particulate composites obtained from techniques such as scanning electron microscopy (SEM) can be easily converted to particle based mesh without loosing much information. This enables more accurate analysis of the chosen composite materials. Therefore, a smooth particle hydrodynamics (SPH) based numerical technique is developed here to investigate the mechanical properties and evolution of debonding process in particulate composites. To perform the numerical study, a Lagrangian corrected SPH (CSPH) method is presented together with an appropriate numerical model for treating material interface discontinuity within the particulate composites. The material interface discontinuity is enforced using an innovative method which combines penalty formulation with a bilinear interface cohesive model for SPH method. The proposed SPH methodology is used in a number of numerical examples involving composite materials and related interface problems. The effect of penalty value on the interface model and of the smoothing length of the SPH method are also analysed during these simulations. The results illustrate the effectiveness, robustness and potential of the developed methodology. It is concluded that the proposed numerical techniques can be easily and effectively applied to simulate multi-phase composites with various interface conditions and, can provide useful information regarding the inherent mechanism of damage evolution and fracture of particulate or fibre reinforced composites. (C) 2009 Elsevier B.V. All rights reserved.
Simplicity of mesh generation and robustness against mesh entanglement during large deformations are key attractive features of particle based methods. These features can be exploited in number of engineering problems where traditional techniques suffer due to aforementioned limitations. Numerical modelling of particulate composites is one of such ideal engineering applications where particle based methods can be effectively used due to their simplicity and robustness. Complicated geometrical configurations of particulate composites obtained from techniques such as scanning electron microscopy (SEM) can be easily converted to particle based mesh without loosing much information. This enables more accurate analysis of the chosen composite materials. Therefore, a smooth particle hydrodynamics (SPH) based numerical technique is developed here to investigate the mechanical properties and evolution of debonding process in particulate composites. To perform the numerical study, a Lagrangian corrected SPH (CSPH) method is presented together with an appropriate numerical model for treating material interface discontinuity within the particulate composites. The material interface discontinuity is enforced using an innovative method which combines penalty formulation with a bilinear interface cohesive model for SPH method. The proposed SPH methodology is used in a number of numerical examples involving composite materials and related interface problems. The effect of penalty value on the interface model and of the smoothing length of the SPH method are also analysed during these simulations. The results illustrate the effectiveness, robustness and potential of the developed methodology. It is concluded that the proposed numerical techniques can be easily and effectively applied to simulate multi-phase composites with various interface conditions and, can provide useful information regarding the inherent mechanism of damage evolution and fracture of particulate or fibre reinforced composites. (C) 2009 Elsevier B.V. All rights reserved.
1-Chloro-2,2-bis(4-chlorophenyl)ethene(p,p'-DDMU),a metabolite of either 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (pp'-DDD) or 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene (p,p'-DDE), which is degraded from 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDT), was detected in a variety of environmental matrices of the Pearl River Delta (PRD), South China, including fish, fish feeds, semidigested fish stomach contents, marine surface sediment, surface soil, atmospheric gaseous phase, and particulates, rainwater, and coastal rainwater. For fish species,the concentrations of p,p'-DDMU were significantly higher in farmed fish than in marine wild fish, with the highest value obtained in seawater farmed fish species (mean/median values of 262/173 ng/g lipid). The relative abundance of p,p'-DDMU to total DDTs (sum of o,p'-and p,p'-DDT, DDD, and DDE) was higher in samples of marine origin (similar to 5%) than in those of terrestrial origin (similar to 2%). Because p,p'-DDD was considerably abundant in all samples and a negative linear correlation was found between p,p'-DDD/(p,p'-DDD + p,p'-DDE) and p,p'-DDMU/DDTs in the marine sediments (r(2) = 0.73) and seawater farmed fish (r(2) = 0.29) under investigation, it is possible that DDMU was partially dehydrochlorinated from DDD in the environment of the PRD. A fugacity-based assessment suggested that p,p'-DDMU is likely to transport from sediment to seawater and then to air and from soil to air. The ubiquity of p,p'-DDMU in the PRD indicates that it may also be widespread worldwide particularly in countries with large amounts of DDT used currently and/or historically. Given the potential risk of p,p'-DDMU to human health, more efforts should be directed toward to this previously overlooked contaminant.
On the basis of a one-year (from October 2006 to September 2007) sampling campaign, 34 air samples and 23 bulk precipitation samples were collected in the Pearl River Delta (PRO) in southern China and analyzed for polybrominated diphenyl ethers (PBDEs). Fifteen tri- to deca-BDE congeners (sum of which is defined as Sigma 15PBDE) were detected in more than 70% of the samples. In three urban-rural regions, Sigma 15PBDE concentrations ranged from 77 to 372 pg/m(3) in air (particulate + vapor) and 1.98 to 15.5 ng/L in rain (particle + dissolved) from Dongguan, from 195 to 1450 pg/m(3) in air and 4.71 to 17.2 ng/L in rain from Shunde, and from 23.7 to 148 ng/L in rain from Guangzhou. Among the BDE congeners, BDE-209 was the predominant component Linear correlations between the gas-particle partition coefficients (K-p) and the subcooled vapor pressures (P) of individual BDE congeners were observed for both the wet and dry seasons, but the slopes (-0.572 to -0.525) of the fitted equations all substantially deviated from equilibrium condition (slope = -1). The total washout ratio by bulk rainfalls was determined to be 2 x 10(3) for tri-BDEs and 6 x 10(4) for BDE-209. The estimated annual dry and wet depositional rates were 6720 and 2460 kg/yr, respectively, for BDE-209, and 7270 and 2940 kg/yr for Sigma 15PBDE in the PRO, indicating a dominant pathway for PBDEs input into the PRD soil and aquatic environments.