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In compact spinning with inspiratory groove, the computational fluid dynamic model, computed with parallel technologies and Fluent 6.3, was developed to simulate the flow field in the compact zone with 3D computational fluid dynamic technology. Flowing state, distributions of static pressure and velocity in the compact zone were characterized and analyzed. The results showed that the compact principle of compact spinning with inspiratory groove consists of compact by airflow and compact by the shape of the inspiratory groove, and the static pressure in the condensing zone is negative, as well as the velocity of airflow in the compact zone is not zero. The fluctuation of the static pressure and velocity near the bottom of the inspiratory groove is relatively bigger and the number of the fluctuation is equal to the number of the round holes in the compact zone.

Due to the adverse impact of DDTs on ecosystems and humans, a full fate assessment deems a comprehensive study on their occurrence in soils over a large region. Through a sampling campaign across China, we measured the concentrations, enantiomeric fractions (EFs), compound-specific carbon isotope composition of DDT and its metabolites, and the microbial community in related arable soils. The geographically total DDT concentrations are higher in eastern than western China. The EFs and δ13C of o,p’-DDT in soils from western China show smaller deviations from those of racemic/standard compound, indicating the DDT residues there mainly result from atmospheric transport. However, the sources of DDT in eastern China are mainly from historic application of technical DDTs and dicofol. The inverse dependence of o,p’-DDT and p,p’-DDE on temperature evidences the transformation of parent DDT to its metabolites. Initial usage, abiotic parameters and microbial communities are found to be the main factors influencing the migration and transformation of DDT isomers and their metabolites in soils. In addition, a prediction equation of DDT concentrations in soils based on stepwise multiple regression analysis is developed. Results from this study offer insights into the migration and transformation pathways of DDTs in Chinese arable soils, which will allow data-based risk assessment on their use.

Spatially splitting nonclassical light beams is in principle prohibited due to noise contamination during beam splitting. We propose a platform based on thermal motion of atoms to realize spatial multiplexing of squeezed light. Light channels of separate spatial modes in an anti-relaxation coated vapor cell share the same long-lived atomic coherence jointly created by all channels through the coherent diffusion of atoms which in turn enhances individual channel's nonlinear process responsible for light squeezing. Consequently, it behaves as squeezed light in one optical channel transferring to other distant channels even with laser powers below the threshold for squeezed light generation. An array of squeezed light beams was created with low laser power ∼ mW. This approach holds great promise for applications in multi-node quantum network and quantum enhanced technologies such as quantum imaging and sensing. * Electronic address: heng.shen@physics.ox.ac.uk † Electronic address: yxiao@fudan.edu.cn

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A high amplitude pressure pulse was produced by the shaped charge during perforation. The method of characteristics was applied to study the damaged zone created around the perforating tunnel. The analytical results offered an analytical explanation to the experimental observations made by Pucknell and Behrmann. It was demonstrated that the pore fluid played a major role for the damage surrounding the perforated hole. Introduction Pucknell and Behrmann published an interesting paper on experimental investigation of damaged zone created by shaped-charge perforations. The hole in a fluid-saturated sandstone specimen of diameter 0.1016 m (4 in.) was perforated by charges of strength 3.2, 6.5, or 22 gm. The tests were carried out under realistic reservoir pressures and overburden stresses, and most perforations were shot at an underbalanced condition. After shots, the cores were CAT scanned for distribution of damage, and tested with mercury porosimetry and examined with petrographic microscope for porosity and permeability changes. The following observations were made by the authors:The density and porosity close to the perforation tunnel were not changed, and they remained essentially the same as the rest of the rock.All cores showed spiral fractures around the perforation tunnel. And, in addition to the spiral fractures near the hole, when the hole was perforated with a large charge (i.e, 22 gm), large radial fractures extent beyond the boundary were also observed. The fracture pattern from Fig. 2 of Pucknell and Behrmann's paper is sketched in Fig. 1.There was a significant decrease in permeability near the perforated tunnel. The purpose of this paper is to provide a theoretical explanation for the above observed phenomena by analyzing the shock wave produced by the charges. The perforation by a shaped charge jet was studied by many authors. The charge produced a high velocity fluid jet penetrating into the target. The magnitude of the fluid pressure pulse is of the orders of 10 9 Pa (10 5 psi), and the time duration of the pulse is of the orders of microseconds. The pulse therefore produces a shock wave in the rock medium propagating radially outward from the perforating tunnel. The above listed observations on damage around the tunnel can be explained by examining the behavior of the shock waves produced by the fluid jet. The Biot's dynamic poroelastic equations were used to model the fluid-saturated rock. A brief description of Biot's equation is presented in section II. P. 603^

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