909 resultados para migration of rhizobia


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The migration of phenanthrene and factors affecting its migration in soil in presence of LAS are studied through the simulation of soil column. Results show that:① Through 180 days of leaching, when the LAS concentration is 0.5 or 5mg·L *.1, the phenanthrene residual rate is less than 10 percent and the residue distributes mainly in surface soil(0-5cm);② When LAS concentration is 0.5mg·L *.1, the phenanthrene residual rate in soil is 3-8 times that of LAS concentration being 5mg·L *.1;③ The phenanthrene residual rate in soil is 2.5-6 times that of soil that with organic matter removed.It's shown that the LAS concentration has obvious effect for the phenanthrene residual rate in soil and the organic matter in soil has good cap ability in keeping phenanthrene.

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An electrochemiluminescence (ECL) sensor based on Ru(bpy)(3)(2+)-graphene-Nafion composite film was developed. The graphene sheet was produced by chemical conversion of graphite, and was characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), and Raman spectroscopy. The introduction of conductive graphene into Nafion not only greatly facilitates the electron transfer of Ru(bpy)(3)(2+), but also dramatically improves the long-term stability of the sensor by inhibiting the migration of Ru(bpy)(3)(2+) into the electrochemically inactive hydrophobic region of Nafion. The ECL sensor gives a good linear range over 1 x 10(-7) to 1 x 10(-4) M with a detection limit of 50 nM towards the determination of tripropylamine (TPA), comparable to that obtained by Nafion-CNT.

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Interpretation of high-resolution two-dimensional (2D) and three-dimensional (3D) seismic data collected in the Qiongdongnan Basin, South China Sea reveals the presence of polygonal faults, pockmarks, gas chimneys and slope failure in strata of Pliocene and younger age. The gas chimneys are characterized by low-amplitude reflections, acoustic turbidity and low P-wave velocity indicating fluid expulsion pathways. Coherence time slices show that the polygonal faults are restricted to sediments with moderate-amplitude, continuous reflections. Gas hydrates are identified in seismic data by the presence of bottom simulating reflectors (BSRs), which have high amplitude, reverse polarity and are subparallel to seafloor. Mud diapirism and mounded structures have variable geometry and a great diversity regarding the origin of the fluid and the parent beds. The gas chimneys, mud diapirism, polygonal faults and a seismic facies-change facilitate the upward migration of thermogenic fluids from underlying sediments. Fluids can be temporarily trapped below the gas hydrate stability zone, but fluid advection may cause gas hydrate dissociation and affect the thickness of gas hydrate zone. The fluid accumulation leads to the generation of excess pore fluids that release along faults, forming pockmarks and mud volcanoes on the seafloor. These features are indicators of fluid flow in a tectonically-quiescent sequence, Qiongdongnan Basin. Geofluids (2010) 10, 351-368.

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以大批量制造的生产线制造系统为背景,研究基于agent与holon智能制造思想体系的可重构生产线制造系统实现技术,以提高生产线柔性与可重构能力为目标·深入分析了多agent制造及holonic制造模式体系下智能单元自主决策、协商合作在制造系统环境中的实现与运行机制,在以机械加工线和装配线为代表的不同的工程实际背景与应用环境下该思想体系目前的具体应用情况与实现技术·指出该思想体系面向具体工程背景的有效实施应用是理论研究的关键·最后以某汽车变速器装配生产线制造系统为应用实例,从其规划设计与运行角度,分析了可重构生产线系统的框架设计及具体实现技术与方法·

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Theoretical research, laboratory test and field observation show that most of sediment rock has anisotropic features. It will produce some notable errors when applying isotropic methods such as prestack depth migration and velocity analysis to dada acquired under anisotropic condition; it also has a bad effect on geologic interpretation. Generally speaking, the vertical transverse isotropic media is a good approximation to geologic structure, thus it has an important realistic meaning for anisotropic prestack depth migration theory researching and precise complex geologic imaging if considering anisotropic effect of seismic wave propagation. There are two indispensable parts in prestack depth migration of realistic records, one is proper prestack depth migration algorithm, and the other is velocity analysis using prestack seismic data. The paper consists of the two aspects. Based on implicit finite difference research proposed by Dietrich Ristow et al (1997) about VTI media prestack depth migration, the paper proposed split-step Fourier prestack depth migration algorithm (VTISSF) and Fourier finite difference algorithm (VTIFFD) based on wave equation for VTI media, program are designed and the depth migration method are tested using synthetic model. The result shows that VTISSF is a stable algorithm, it generally gets a good result if the reflector dip is not very steep, while undermigration phenomena appeared in steep dips case; the VTIFFD algorithm bring us better result in steep dips with lower efficiency and frequency dispersion. For anisotropic prestack depth migration velocity analysis of VTI media, The paper discussed the basic hypothesis of VTI model in velocity analysis algorithm, basis of anisotropic prestack depth migration velocity analysis and travel time table calculation of VTI media in integral prestack depth migration. Then , analyzed the P-wave common imaging gather in the case of homogeneous velocity and vertically variable velocity . studied the residual correction in common imaging gather produced by media parameter error, analyzed the condition of flat event and correct depth in common imaging gather . In this case, the anisotropic model parameter vector is , is vertical velocity of a point at top surface, is vertical velocity gradient, and are anisotropic parameter. We can get vertical velocity gradient from seismic data; then the P-wave common imaging gather of VTI media whose velocity varies in vertical and horizontal direction, the relationship between media parameter and event residual time shift of common image gather are studied. We got the condition of flattening common imaging gather with correct depth. In this case the anisotropic model parameter vector is , is velocity gradient in horizontal direction. As a result, the vertical velocity grads can be decided uniquely, but horizontal velocity grads and anisotropic parameter can’t be distinguished if no priori information available, our method is to supply parameter by velocity scanning; then, as soon as is supplied we can get another four parameters of VTI media from seismic data. Based on above analysis, the paper discussed the feasibility of migration velocity analysis in vertically and horizontally varied VTI media, synthetic record of three models are used to test the velocity analysis method . Firstly, anisotropic velocity analysis test is done using a simple model with one block, then we used a model with multiple blocks, thirdly, we analyzed the anisotropic velocity using a part of Marmousi model. The model results show that this velocity analysis method is feasible and correct.

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With the development of oil/gas seismic exploration, seismic survey for fracture/porosity type reservoir is becoming more and more important. As for China, since it has over 60% store of low porosity and low permeability oil/gas reservoir, it’s more urgent to validly describe fracture/porosity type oil/gas trap and proposing the related, developed seismic technique. To achieve mapping fracture/porosity region and its development status, it demands profound understanding of seismic wave propagation discipline in complex fractured/pored media. Meanwhile, it has profound scientific significance and applied worth to study forward modeling of fracture/porosity type media and pre-stacked reverse time migration. Especially, pre-stacked reverse-time migration is the lead edge technique in the field of seismology and seismic exploration. In this paper, the author has summarized the meaning, history and the present state of numerical simulation of seismic propagation in fractured/pored media and seismic exploration of fractured/pored reservoirs. Extensive Dilatancy Anisotropy (EDA) model is selected as media object in this work. As to forward modeling, due to local limitation of solving spatial partial derivative when using finite-difference and finite-element method, the author turns to pseudo-spectral method (PSM), which is based on the global characteristic of Fourier transform to simulate three-component elastic wave-field. Artifact boundary effect reduction and simulation algorithm stability are also discussed in the work. The author has completed successfully forward modeling coding of elastic wave-field and numerical simulation of two-dimensional and three-dimensional EDA models with different symmetric axis. Seismic dynamic and kinematical properties of EDA media are analyzed from time slices and seismic records of wave propagation. As to pre-stacked reverse-time migration for elastic wave-field in fractured/pored media, based on the successful experience in forward modeling results with PSM, the author has studied pre-stacked reverse-time depth-domain migration technique using PSM of elastic wave-field in two dimensional EDA media induced by preferred fracture/pore distribution. At the same time, different image conditions will bring up what kind of migration result is detailed in this paper. The author has worded out software for pre-stacked reverse-time depth-domain migration of elastic wave-field in EDA media. After migration processing of a series of seismic shot gathers, influences to migration from different isotropic and anisotropy models are described in the paper. In summary, following creative research achievements are obtained:  Realizing two-dimensional and three-dimensional elastic wave-field modeling for fractured/pored media and related software has been completed.  Proposed pre-stacked reverse-time depth-domain migration technique using PSM of elastic wave-field.  Through analysis of the seismic dynamic and kinematical properties of EDA media, the author made a conclusion that collection of multi-component seismic data can provide important data basis for locating and describing the fracture/pore regions and their magnitudes and the preferred directions.  Pre-stacked reverse-time depth-domain migration technique has the ability to reconstruct complex geological object with steep formations and tilt fracture distribution. Neglecting seismic anisotropy induced by the preferred fracture/pore distribution, will lead to the disastrous imaging results.

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With the development of oil and gas field exploration, it becomes harder to search new reserves. So a higher demand of seismic exploration comes up. Now 3C3D seismic exploration technology has been applied in petroleum exploration domains abroad. Comparing with the traditional P-wave exploration, the seismic attributes information which provided by 3C3D seismic exploration will increase quickly. And it can derive various combined parameters. The precision of information about lithology, porosity, fracture, oil-bearing properties, etc which estimated by above parameters was higher than that of pure P-wave exploration. These advantages mentioned above lead to fast development of 3C3D seismic technology recently. Therefore, how to apply the technology in petroleum exploration field in China, how to obtain high quality seismic data, and how to process and interpret real data, become frontier topics in geophysical field nowadays, which have important practical significance in research and application. In this paper, according to the propagation properties of P-wave and converted wave, a study of 3C3D acquisition parameters design method was completed. Main parameters included: trace interval, shot interval, maximum offset, bin size, the interval of receiving lines, the interval of shooting lines, migration aperture, maximum cross line distance, etc. Their determination principle was given. The type of 3C3D seismic exploration geometry was studied. By calculating bin attributes and analyzing parameters of geometry, some useful conclusions were drawn. With the method in this paper, real geometries for continental lithology stratum gas reservoir and fractured gas reservoir were studied and determined. In the static method of multi-wave, the near surface P-wave, S-wave parameter investigation method has been advanced, and this method has been applied for the patent successfully; the near surface P-wave, S-wave parameter investigation method and the converted refraction wave first arrival static techniques have been integrally used to improve the effectiveness of converted wave static. In the aspect of converted wave procession, the rotation of horizontal component data, the calculation of converted wave common conversion bin, the residual static of converted wave, the velocity analysis of the common conversion point (CCP), the Kirchhoff pre-stack time migration of converted wave techniques have been applied for setting up the various 3C3D seismic data processing flows based on different geologic targets, and the high quality P-wave, converted-wave profiles have been acquired in the actual data processing. In the aspect of P-wave and converted-wave comprehensive interpretation, the thoughts and methods of using zero-offset S-wave VSP data to calibrate horizon have been proposed; the method of using P-wave and S-wave amplitude ratio to predict the areas of oil and gas enrichment has been studied; the method of inversion using P-wave combined with S-wave has been studied; the various P-wave, S-wave parameters(velocity ratio, amplitude ratio, poisson ratio) have been used to predict the depth, physical properties, gas-bearing properties of reservoirs; the method of predicting the continental stratum lithology gas reservoir has been built. The above techniques have all been used in various 3D3C seismic exploration projects in China, and the better effects have been gotten. By using these techniques, the 3C3D seismic exploration level has been improved.

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The largest mass extinction in the Phanerozoic happened at the end of the Permian. The microbialites formed in the extreme environments after the mass extinction has become a hotspot for geologists and paleontologists throughout the world. The dendroid microbialites that were described for the first time in 1999 from the Permian-Triassic boundary section at Laolongdong, Chongqing, have been studied by many geologists from China and overseas. Two important viewpoints about their origin have been proposed. Some researchers believed that they resemble Quaternary travertine shrubs in form, and may belong to microbialites. Some other researchers proposed that the dendroid structure is composed of clots formed by coccoidal cynaobacteria, and is microbialite. Our detailed survey on the section reveals that: (1) there is an interval of speckled “microbialite” in the section, and it underlies the dendroid “microbialite”, (2) the dendroid “microbialite” does not always have dendroid appearance; they are dendroid only in very local places; they are not dendroid in most places; for this reason, they are not comparable to recent tufa; (3) the volume of the dendroid structure greatly increases toward the top of the dendroid microbialite interval: accounting to 70% of the whole rock in the top part. This distribution pattern implies that the formation of this structure may be related to downward migration of the diagenetic fluid. Examination of thin sections reveals that the dendroid structure or point-like structure in the “microbialite” look as lighter areas in the thin sections and are composed of large blocky clear calcites containing scattered yellow dirty small calcite rhombi and irregular “points” of relict lime mudstone or wackestone or packstone. Their formation is by any one of the following two processes: (1) dissolution → filling of large blocky calcite; (2) dolomitization → dedolomitization → dissolution by meteoric fresh water → filling by large blocky calcites. It has been found that there are at least two sea-level falls during the P-T transition. As the sea level fall, the carbonate deposits came into supratidal environment, and suffered dolomitization caused by evaporative fluid or mixing water of sea water and meteoric water. Since the fluid migrated downward from the top of the deposits and in random pathway, the dolomitization formed dendroid or speckled dolomitic areas. As the deposits came into subaerial environments, the meteoric fresh water migrated along the dendroid or speckled dolomitic area with higher porosity, and dissolution happened, which caused the rock became spongy or alveolate. In later time, after the strata came into phreatic zone, large clear blocky calcites grew in and filled the pores in the spongy areas. The dendroid and speckled structure were formed in this way, rather than composed of clots formed by coccoid cyanobecteria. The microbial fossils in Laolongdong section include two types. The first is the tube-like cyanobecteria in middle Bed 3, which are generally less than 1 mm in length, taper toward one end, and are internally filled by microspars. They are straight or sinuous, with micritic wall 0.005~0.01 mm thick. Since this kind of microbial fossils are abundant in middle Bed 3, this rock belongs to microbialite. The second type occurs in Bed 5 and lower and middle Bed 6. They are irregular globular in shape, generally 0.2 ~ 0.5 mm in size, with several outward progresses, and internally filled by one layer of needle-like calcite cements on the wall and the large blocky calcite in the inner space. According to their shape and preservation way, it is inferred that this kind of fossils were formed from some kind of bacterial colony. The bacterial colony may be cuticle in composition, since it has some hardness as it is indicated by its resistance to deposit loading. These organisms discomposed during diagenetic time, and formed good porosity. In later diagenetic time, these pores were firstly cemented by needle-like calcites and later filled by large blocky calcites. So, the bacterial colony promoted the formation of dendroid and speckled structures. However, they did not always form such structures. On the other hand, even though no bacterial colony or other microbes or any kind of fossils were present, dendroid or speckled structures can form. Bed 4 of Laolongdong section contains abundant gastropods but no microbial fossils, and is not microbialite, even though it is speckled. The top of Bed 6 is dendroid, but contain no microbial fossils, and is not micrbialite.

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Petroleum and natural gas is an important strategic resources. The short of the reserves will block the development of economy and threaten the safety of nation, along with the main oil fields of our country coming to the height of power and splendor of the exploitation and exploration. Therefore, it makes a great sense to inaugurate new explorative field and increase the reserves of petroleum and natural gas. Magnetic exploration is a main method of geophysics exploration. the developing observation apparatus and the perfect processing method provide wide space for magnetic exploration in these years. The method of magnetic bright spot is an application of magnetic exploration. The vertical migration of the hydrocarbon changes physical and chemical environment above the hydrocarbon reservoir, the new environment make tervalent iron translate into bivalent iron, that produce small scale magnetic anomaly, that is magnetic bright spot. The method of magnetic bright spot explores oil and gas field by the relation between the hydrocarbon and magnetic anomaly. This paper systemically research to pick-up and identify magnetic bright spot combining an oil field item, then point out advantaged area. In order to test the result, the author use the seismic information to superpose the magnetic bright spot, that prove the magnetic bright spot is reliable. then, the author complete a software to pick and identify the magnetic bright spot. The magnetic basement is very important to research forming and evolvement of the basin, especially, it is a crucial parameter of exploring residual basin in the research on pre-Cenozoic residual. This paper put forward a new method to inverse the interface of the magnetic layer on the basis of previous work, that is the method of separation of magnetic field step by step. The theory of this method is to translate the result of magnetic layer fluctuation to the result of magnetization density change, and the magnetic layer is flat, the paper choose thickness of magnetic layer as unit thickness, and define magnetic layer as a unit-thickness layer in order to convenient calculation, at the same time, define the variational magnetization density as equivalent magnetic density. Then we translate the relation between magnetic field and layer fluctuation to the relation between magnetic field and equivalent magnetic density, then, we can obtain the layer fluctuation through calculating equivalent magnetic density. Contrast to conventional parker method, model experimentation and example checkout prove this method is effective. The merit of this method is to avoid flat result in a strongly fluctuant area because of using a uniform average depth, the result of this method is closer to the fact, and this method is to inverse equivalent magnetic density, then translate equivalent magnetic density to layer fluctuation, this lays a foundation to inverse variational magnetic density in the landscape orientation and portrait.