1,530 research outputs found

    Generalized Second-Order Thomas-Fermi Method for Superfluid Fermi Systems

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    Using the \hbar-expansion of the Green's function of the Hartree-Fock-Bogoliubov equation, we extend the second-order Thomas-Fermi approximation to generalized superfluid Fermi systems by including the density-dependent effective mass and the spin-orbit potential. We first implement and examine the full correction terms over different energy intervals of the quasiparticle spectra in calculations of finite nuclei. Final applications of this generalized Thomas-Fermi method are intended for various inhomogeneous superfluid Fermi systems.Comment: 8 pages, 10 figures, PR

    Measurement of Adhesion Energy of Electrospun Polymer Membranes Using a Shaft-loaded Blister Test

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    This study aims to examine the adhesion work of electrospun polymer nano- and micro-fibers. The adhesion energy at the interface of electrospun membrane and a rigid substrate is characterized by a shaft-loaded blister test (SLBT). By controlling the processing parameters, polyvinylidene fluoride (PVDF) fibrous membranes are prepared with fiber diameters ranging from 201 ± 86 nm to 2,724 ± 587 nm. The adhesion energy between electrospun membrane and rigid substrate increases from 8.1 ± 0.7 mJ/m2 to 258.8 ± 43.5 mJ/m2 by use of smaller fiber diameters. Adhesion energies between electrospun PVDF membranes and SiC substrates made of different grain sizes are evaluated. Fibrous membrane produces an adhesion energy as high as 420.1 ± 62.9 mJ/m2 in contact with SiC substrate with a 68 μm grit size. The SLBT methodology is extended to understand the adhesion energy between electrospun membranes. The increase in adhesion work is attributed to an increased area between fiber delaminated surfaces and surface asperities

    Numerical simulation of pressure pulse decay experiment on crushed low permeability rocks considering Klinkenberg effect and gas absorption/desorption

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    Pressure pulse decay method is widely used for permeability tests for low permeability rock plug samples. This method can be used for crushed grain samples by removing the downstream chamber in standard pulse decay tests. Processes in pulse decay tests for low permeability crushed shale are investigated using numerical simulation. Both the Klinkenberg slip effect for gas flows in low permeability rock and the gas absorption/desorption in the porous matrix are considered. The complete mathematical model is set up to include the two effects. Deviation of the numerical pulse decay curve from the analytical one with an assumption that the pressure keeps a constant in the porous sample is investigated. The relative importance of gas absorption/desorption and gas compressibility is also investigated quantitatively. According to the present investigation, gas compressibility and adsorption both make negative contributions to the permeating process. A potential two-curve method is proposed to decide absolute permeability and the Klinkenberg coefficient when these two parameters cannot be distinguished using one pulse decay curve during the inverse fitting procedure. These two parameters can be determined at the same time only if the experiment is conducted under big initial pressure difference and the Klinkenberg coefficient has at least the same order of magnitude as the pressure

    Small-amplitude collective modes of a finite-size unitary Fermi gas in deformed traps

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    We have investigated collective breathing modes of a unitary Fermi gas in deformed harmonic traps. The ground state is studied by the superfluid local density approximation (SLDA) and small-amplitude collective modes are studied by the iterative quasiparticle random phase approximation (QRPA). The results illustrate the evolutions of collective modes of a small system in traps from spherical to elongated or pancake-shaped deformations. For small spherical systems, the influences of different SLDA parameters are significant, and, in particular, a large pairing strength can shift up the oscillation frequency of collective modes. The transition currents from QRPA show that the compressional flow patterns are nontrivial and dependent on the deformation. Finally, the finite-size effects are demonstrated to be reasonable when progressing towards larger systems. The hydrodynamical results of collective frequencies can be reproduced by SLDA-QRPA with reduced pairing strengths. Our studies indicate that experiments on small and medium systems are valuable for understanding effective interactions in systems with varying sizes and trap deformations.Peer reviewe

    Effective solid-to-fluid heat transfer coefficient in EGS reservoirs

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    The present work developed a three-equation local thermal non-equilibrium model to predict the effective solid-to-fluid heat transfer coefficient in the enhanced geothermal system reservoirs based on the volume averaging method. Due to the high rock-to-fracture size ratio, the solid thermal resistance effect in the internal rocks cannot be neglected in the effective solid-to-fluid heat transfer coefficient. The present three-equation local thermal non-equilibrium model can consider the dynamic variation of the solid thermal resistance in transient heat transfer by introducing the penetration temperature difference. The model was validated by comparison with pore-scale numerical simulations and macro-scale LTNE model numerical simulations. The results show that the three-equation local thermal non-equilibrium model has a high accurac

    Adaptive estimation and control of MR damper for semi-active suspension systems

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    手术室风险管理

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    Objective: To study the risk management of operating room and to improve operating room efficiency. Methods: Firstly, make clear   the internal risk management and external regulatory frameworks, organizational principles and their respective functions on the basis of the risk management of operating room. Results: The checklist approach was employed for extensive identification and potential risk in operating room, even if the risk could be controlled. Conclusion: This study designs risk management plans and establishes a risk register, to strengthen the emergency response capacity and improve operating room efficiency.目的  研究手术室风险管理,提高手术室工作效率。方法  基于手术室风险管理首先要明确内部和外部的管理框架,组织原则及各自的职能。结果  采用检查列表的方式,广泛识别手术室目前存在的和可能发生的风险,即使出现风险可控。结论  研究设计手术室风险管理计划,建立风险登记簿,加强突发事件应对能力,提高了手术室工作效率
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