长期施肥对黑土POM分布及其碳水化合物特性的影响

本文以吉林省公主岭“国家黑土肥力与肥料效益长期定位监测基地”的黑土为材料，研究长期施肥对黑土POM的分布及POM（FPOM和OPOM）中碳水化合物特性的影响，结果表明： 有机肥及有机肥与化肥配施显著提高了土壤中碳水化合物的含量，促进了植物来源的中性糖和真菌来源的氨基糖在土壤中的积累。在有机质含量较高的黑土上长期施用高量有机肥会出现养分过剩的现象。不同施肥处理下黑土有机质中中性糖的相对含量与不施肥相比无显著变化，氨基糖的相对含量则显著增加。随着有机肥施用量的增加，土壤中中性糖的含量也随之显著增加，而氨基糖则没有明显变化。 有机肥及有机肥与化肥配施能显著增加黑土中POM以及POM-C、POM-N和碳水化合物的含量，且均随有机肥施用量的增加而增加。各个处理中OPOM的碳、氮和碳水化合物含量远远高于FPOM。POM中各个单糖对施肥的响应与碳水化合物的总量基本一致。单施高量有机肥及有机肥与化肥配施均能显著提高POM中中性糖和氨基糖占有机质的比例，单施低量有机肥对POM中氨基糖和FPOM中中性糖占有机质的比例作用不明显，而能显著增加OPOM中中性糖占SOM的比例。在POM的中性糖中葡萄糖和木糖对SOM的贡献较大，氨基糖中氨基葡萄糖的贡献较大。OPOM中碳水化合物对SOM的贡献大于FPOM。FPOM中中性糖主要来源于植物，而OPOM中则主要来源于植物和微生物。在短期范围内，施肥并没有引起POM中两种来源氨基糖比例的显著变化，而从长期来看，有机肥处理却使POM中细菌源氨基糖的积累得到了加强。单施化肥对黑土有机质和黑土POM的含量以及二者中的碳、氮和碳水化合物的含量和组成均没有显著的影响。

Numerical simulation of tides and tidal currents in Liaodong Bay with POM

A three-dimensional ocean circulation model, called Princeton Ocean Model (POM), is employed to simulate tides and tidal currents in Liaodong Bay. The nested grid technique is adopted to improve the computation precision. Computed harmonic constants of M-1, M-2 tides at five tidal gauge stations and surface elevations at two oil platforms are compared with those observed, and show good agreements with them. Based on the calculated results, the co-amplitude and co-phase tag lines of nil and M-2 tidal constituents, the residual current field of M-2 constituent, tidal form, tidal Current ellipse and the moving style of tidal current are given. It is found that diurnal tidal constituents have no amphidromic point whereas semi-diurnal constituents have one in the region of interest. Meanwhile, some meaningful results are concluded and presented, which are conducive to a thorough knowledge of the characteristics of tides and tidal currents in the Liaodong Bay.

An integrated air-POM syngas/dimethyl ether process from natural gas

A Cu-Zn-Al methanol catalyst combined with HZSM-5 was used for dimethyl ether (DME) synthesis from a syngas containing nitrogen, which was produced by air-partial oxidation of methane (air-POM). Air-POM occurred at 850 degreesC, 0.8 MPa, CH4/air/H2O/CO2 ratio of 1/2.4/0.8/0.4 over a Ni-based catalyst modified by magnesia and lanthanum oxide with 96% CH4 conversion and constantly gave syngas with a H-2/CO ratio of 2/1 during a period of 450 h. The obtained N-2-containing syngas was used directly for DME synthesis. About 90% CO per-pass conversion, 78% DME selectivity and 70% DME yield could be achieved during 450 h stability testing under the pressure of 5.0 MPa. the temperature of 240 degreesC and the space velocity of 1000 h(-1). (C) 2002 Elsevier Science B. V. All rights reserved.

Pom de poemaris : editar des de l'escola. 'Ramo de poemarios : editar desde la escuela'

Este art??culo forma parte de la monograf??a 'Editar avui' (Editar hoy)

Anàlisi del camp d'ones internes en sistemes limnològics petits. Simulacions amb el POM

Aquí hem aplicat el Princeton Ocean Model als embassaments de Sau i Boadella, situats a Catalunya, Espanya. Les simulacions s'han realitzat a l'estació d'estiu, quan la columna d'aigua està estratificada de forma contínua, i sota un règim de brisa amb velocitats de fins a 4 m/s. Basant-nos en aquestes simulacions hem analitzat el camp d'ones internes i comparat els resultats numèrics amb dades experimentals disponibles. El model reprodueix adequadament tots els modes observats en l'espectre de la velocitat i temperatura mesurades i ajuda a identificar els diferents modes. Les simulacions mostren la importància dels modes rotacionals en el camp d'ones internes dels embassaments estratificats. En el període estudiat, el radi de Rossby per l'embassament de Sau és de l'ordre de 100 m, que és varies vegades més petit que la amplitud de l'àrea lacustre de l'embassament, i el número de Rossby és de l'ordre de 0.1, corroborant la importancia de l'efecte de Coriolis.

Numerical solution of the eXtended Pom-Pom model for viscoelastic free surface flows

In this paper we present a finite difference method for solving two-dimensional viscoelastic unsteady free surface flows governed by the single equation version of the eXtended Pom-Pom (XPP) model. The momentum equations are solved by a projection method which uncouples the velocity and pressure fields. We are interested in low Reynolds number flows and, to enhance the stability of the numerical method, an implicit technique for computing the pressure condition on the free surface is employed. This strategy is invoked to solve the governing equations within a Marker-and-Cell type approach while simultaneously calculating the correct normal stress condition on the free surface. The numerical code is validated by performing mesh refinement on a two-dimensional channel flow. Numerical results include an investigation of the influence of the parameters of the XPP equation on the extrudate swelling ratio and the simulation of the Barus effect for XPP fluids. (C) 2010 Elsevier B.V. All rights reserved.

Numerical simulation of drop impact and jet buckling problems using the eXtended Pom-Pom model

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Numerical solution of the eXtended Pom-Pom model for viscoelastic free surface flows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Casos de estudios de impacto ambiental: obras para el gasoducto Atasta-ciudad Pemex en la laguna Pom, México

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