松软突出煤层复合排渣钻进技术试验研究

为提高煤矿松软煤层瓦斯抽采钻孔施工深度和抽采效果,以中风压(0.7～1.2 MPa)复合排渣钻进技术为基础,采用不同规格的螺旋钻具组合配合相应的工艺参数进行现场试验,比较不同钻具组合的应用情况,选择适应松软突出煤层的最优钻具组合与配套工艺,达到高效施工全煤长钻孔的目的。     

2016年3—5月T639、ECMWF及日本 模式中期预报性能检验

对2016年3—5月T639、ECMWF及日本（文中简称JP）数值模式的中期预报产品进行了分析和检验。结果表明：3个模式对亚洲中高纬环流形势的调整和演变均具有较好的预报性能,其中ECMWF模式预报效果最好。3个模式对850 hPa温度的转折性变化趋势均有较好的预报能力,其中对南方地区温度变化的预报能力明显优于北方地区,ECMWF综合预报效果最好。此外,选取了2016年3月3—5日的沙尘天气过程进行个例分析,发现T639和ECMWF模式对此次过程的地面高压系统的中期预报指示意义较好。     

Acoustic plane-wave reflection from a rough surface over a random fluid half-space

Plane-wave reflection from a rough surface overlying a fluid half-space, with a sound speed distribution subject to a small and random perturbation, is considered. A theory based upon a boundary perturbation method in conjunction with a formulation derived from Green's function for the coherent field in the random medium have been applied to a typical oceanic environment to study their effects on the plane-wave reflection. By considering the coherent field itself, the plane-wave reflection may be obtained straightforwardly through a procedure consistent with the formalisms currently employed in rough surface scattering. The results show that both the rough surface and medium inhomogenieties may reduce the plane-wave reflection, however, the characteristics of the curves representing their effects are different, enabling us to identify the dominant scattering mechanism. The results for the coherent reflection due to the individual scattering mechanism are compatible with those found in the existing literature.     

亚心形扁藻培养基的筛选与优化

在500mL三角瓶中对亚心形扁藻培养基的筛选与优化结果表明,原“海洋三号”培养基中需添加0.8 g/L的NaHCO_3,且 K_2HPO_4的浓度需由原来的 0.01g/L调整为 0.06 g/L。10 L全自动封闭式光生物反应器分批培养结果表明,优化后的“海洋三号”培养基不仅可加快亚心形扁藻的生长速率而且可延长生长时间,培养 4 d时最高藻细胞密度可达 426×10~4细胞/mL,比原“海洋三号”培养基的最高培养密度提高42％。优化后的“海洋三号”培养基为亚心形扁藻的最适培养基。     

Hydroelastic Response Analysis of Mat-Like VLFS over A Plane Slope in Head Seas

1 .IntroductionIntheexploitationofoceanresourcesandintheutilizationofoceanspaces,verylargefloatingstructures (VLFS)suchasMega FloatinJapan (Isobe ,1 999)andMobileOffshoreBase (MOB)inUSA (Remmers ,1 999)playasignificantrole .However,owingtotheirlargesizesandrelativelylowbendingrigidities ,theirhydroelasticresponsesinwavesareofthemostconcern .ManystudieshavebeencarriedoutforthepredictionofthehydroelasticresponsesofVLFS′s (Kashiwagi,2 0 0 0 ;Cui,2 0 0 2 ) .However,inalmostallofthesestu…     

Bipolar molecular outflows

Summary Bipolar molecular outflows are a ubiquitous phenomenon in the process of star formation. We review the main observational properties of the outflows around young stellar objects, highlighting the recent wealth of information provided by the new generation of large radiotelescopes operating at millimeter wavelengths (in particular the IRAM 30-m, the NRO 45-m, and the JCMT 15-m dishes). The observations of outflows containing molecular, jet-like flows and bullets are discussed in detail, as they provide key information for understanding origin and evolution of the outflows. We also discuss a number of closely related issues: the evidence for dense shocked gas associated with the flows, the interaction of the outflows with the ambient dense cores, the evolutionary status of the sources driving the outflows, the properties of circumstellar disks, and theoretical models of the origin of the neutral winds. All these areas are important for developing a plausible scenario for the formation and evolution of the bipolar molecular outflows.This article was processed by the author using the Springer-Verlag T_EX AAR macro package 1991.     

Cooling flows in clusters of galaxies

Summary X-ray images and spectra of clusters of galaxies show strong evidence for cooling flows. In many clusters, the hot gas in the core is cooling at rates of 100Myr^–1 and greater. Few traces of the cooled gas have been observed, but it probably forms into low-mass stars (perhaps brown dwarf or even Jupiter-mass objects). X-ray surface-brightness profiles show that the cooling gas is highly inhomogeneous. Overdense gas cools rapidly to form cooled clumps distributed throughout the flow, with little of the gas ever reaching the cluster centre. Cooled and cooling clumps are disrupted because of their motion relative to the remainder of the gas, tending to produce small cooled fragments and, ultimately, low-mass stars. Large molecular clouds, which are the sites of massive star formation in our galaxy, do not occur in the outer parts of cooling flows. There is evidence of larger gas clumps and the formation of more massive stars in the central few kpc of some cooling flows. It is argued that cooling flows efficiently form dark matter. This has wider implications for the formation of dark matter in massive galaxies.     

Displacement ring load Green's functions for saturated porous transversely isotropic tri‐material full‐space

Based on the Biot's poroelastic theory and using scalar potential functions both the ring load and point load displacement Green's functions for a transversely isotropic saturated porous full‐space composed of an upper half‐space, a finite thickness middle layer and a lower half‐space is analytically presented for the first time. It is assumed that each region consists of a different transversely isotropic material. The equations of poroelastodymanics in terms of the solid displacements and the pore fluid pressure are uncoupled with the help of two scalar potential functions, so that the governing equations for the potential functions are either a second order wave equation or a repeated wave‐heat transfer equation of sixth order. With the aid of Fourier expansion with respect to circumferential direction and Hankel integral transforms with respect to the radial direction in cylindrical coordinate system, the response is determined in the form of line integrals in the real space, followed by theorem of inverse Hankel integral transforms. The solutions degenerate to a single phase elastic material, and the results are compared with previous studies, where an excellent agreement may be observed with the results provided in the literature. Some examples of displacement Green's functions are finally given to illustrate the solution. Copyright © 2016 John Wiley & Sons, Ltd.     

A stabilized assumed deformation gradient finite element formulation for strongly coupled poromechanical simulations at finite strain

An adaptively stabilized finite element scheme is proposed for a strongly coupled hydro‐mechanical problem in fluid‐infiltrating porous solids at finite strain. We first present the derivation of the poromechanics model via mixture theory in large deformation. By exploiting assumed deformation gradient techniques, we develop a numerical procedure capable of simultaneously curing the multiple‐locking phenomena related to shear failure, incompressibility imposed by pore fluid, and/or incompressible solid skeleton and produce solutions that satisfy the inf‐sup condition. The template‐based generic programming and automatic differentiation (AD) techniques used to implement the stabilized model are also highlighted. Finally, numerical examples are given to show the versatility and efficiency of this model. Copyright © 2013 John Wiley & Sons, Ltd.