Role of snow depth in spring of Tibetan Plateau in onset of South China Sea summer monsoon

The role of snow depth of Tibetan Plateau in the onset of South China Sea summer monsoon and the influence of ENSO on snow depth of Tibetan Plateau are investigated with use of data from ECMWF reanalysis and NCEP/NCAR reanalysis. The results are as follows: (1) The snow depth data from ECMWF reanalysis are tested and reliable, and can be used to study the influence of snow depth of Tibetan Plateau on the onset of South China Sea summer monsoon; (2) Anomaly of snow depth of Tibetan Plateau causes anomaly in air temperature and its contrast between the Indian Ocean and the continent resulting in easterly wind anomaly over 500 hPa and hence as well as in the atmospheric circulation in the lower layer. For the year of negative anomaly of snow depth a westerly wind anomaly with a cyclone pair takes place, while for positive anomaly of snow depth an easterly anomaly occurs with an anticyclone pair; (3) While positive anomaly of SST occurs in the eastern Pacific Ocean, positive anomaly of air pressure also takes place over the eastern Indian Ocean and the South China Sea, causing stronger meridional pressure gradient between the ocean and continent and then westerly wind anomaly. At the same time, the atmospheric pressure increases in the northern Tibetan Plateau, northerly wind gets stronger, and subtropical front strengthens. All of these are favorable for snowfall over Tibetan Plateau.

油气输导体系研究及应用─以准噶尔盆地东部白家海凸起侏罗系为例

Baijiahai uplift is an important hydrocarbon accumulation belt in eastern Jungger Basin, on which Cainan oilfield and lithologic hydrocarbon reservoir named Cai 43 have been discovered and both of them share the same target formation of Jurassic. However, in the subsequent exploration at this region, several wells that designed for lithologic traps of Jurassic were eventually failed, and that indicates the controlling factors of lithologic reservoir distribution are far more complicated than our previous expectation. This dissertation set the strata of the Jurassic in well Cai 43 region as the target, and based on the integrated analysis of structure evolution、fault sealing ability、simulations of sedimentary microfacies and reservoir beds、distribution analysis of high porosity-high permeability carrier beds、drive forces of hydrocarbons、preferential conduit system and conduit model as well as critical values of the reservoir physical properties for hydrocarbon charging, a special method that different from the conventional way to predict favorable lithologic traps was established. And with this method the controlling factors of the hydrocarbon reservoirs formation are figured out, and further more, the favorable exploration targets are point out. At Baijiahai uplift, fault plays as a crucial factor in the process of the hydrocarbon reservoir formation. In this study, it is found out that the availability of a fault that work as the seal for oil and gas are different. The critical value of the lateral mudstone smear factor (Kssf), which is used to measure the lateral sealing ability of fault, for oil is 3.9 while that for gas is 2.1; and the critical value of vertical sealing factor (F), which similarly a measurement for the vertical sealing ability of fault, for oil is 7.3 while that for gas is 5.1. Dongdaohaizi fault belt that possessed well lateral sealing ability since later Cretaceous have bad vertical sealing ability in later Cretaceous, however, it turns to be well now. Based on the comparison of the physical properties that respectively obtained from electronic log calculating、conventional laboratory rock analysis and the additive-pressure bearing laboratory rock analysis, we established the functions through which the porosity and permeability obtained though conventional method can be converted to the values of the subsurface conditions. With this method, the porosity and permeability of the Jurassic strata at the time of previous Tertiary and that in nowadays are reconstructed respectively, and then the characteristics of the distribution of high porosity-high permeability carrier beds in the evolution processes are determined. With the result of these works, it is found that both well Cai 43 region and Cainan oilfield are located on the preferential conduit direction of hydrocarbon migration. This conclusion is consistent with the result of the fluid potential analysis, in which fluid potential of nowadays and that of later Cretaceous are considered. At the same times, experiment of hydrocarbon injection into the addictive-pressure bearing rock is designed and conducted, from which it is found that, for mid-permeability cores of Jurassic, 0.03MPa is the threshold values for the hydrocarbon charging. And here, the conception of lateral pressure gradient is proposed to describe the lateral driving force for hydrocarbon migration. With this conception, it is found that hydrocarbons largely distributed in the areas where lateral pressure gradient is greater than 0. 03MPa/100m. Analysis of critical physical properties indicated that the value of the critical porosity and critical permeability varied with burial depth, and it is the throat radius of a certain reservoir bed that works as a key factor in controlling hydrocarbon content. Three parameters are proposed to describe the critical physical properties in this dissertation, which composite of effective oil-bearing porosity、effective oil-bearing permeability and preferential flow coefficient. And found that critical physical properties, at least to some extent, control the hydrocarbon distribution of Jurassic in Baijiahai uplift. Synthesize the content discussed above, this dissertation analyzed the key factors i.e., critical physical properties、driving force、conduit system and fluid potential, which controlled the formation of the lithologic reservoir in Baijiahai uplift. In all of which conduit system and fluid potential determined the direction of hydrocarbon migration, and substantially they are critical physical properties of reservoir bed and the lateral pressure gradient that controlled the eventually hydrocarbon distribution. At the same times, sand bodies in the major target formation that are recognized by reservoir bed simulation are appraised, then predict favorite direction of the next step exploration of lithologic reservoir.

西峰油田特低渗透油藏渗流机理及开发对策研究

Micro-pore-throat, micro-fracture and low permeability are the most obvious characters of Xifeng ultra-low permeability reservoir, and threshold pressure gradient and medium deformation during the period of oilfield developing results non-linear seepage feature of the formation liquid flowing in the porous medium underground. It is impossible to solve some problems in the ultra-low permeability reservoir development by current Darcy filtration theory and development techniques. In the view of the characters of ultra-low permeability and powerful-diagenesis and fracture up-growth, the paper quantitatively characterizes of through-going scope for reservoir parameters together with some materials such as similarity field outcrop, rock core, drilling, well logging and production dynamic, which provides geological base for further development adjustment. Based on the displacement experiment of different kinds of seepage fluid and oil-water two phases, this paper proves the relationship between threshold pressure gradient and formation permeability in experiment and theory, which is power function and its index is about -1. The variation rule and the mechanism of oil-water two phases threshold pressure gradient are studied. At the same time, based on the experiment of medium deformation, the variation rule of formation physical property parameters and the deformation mechanism are researched, and the influential factors on the medium deformation are analyzed systematically. With elastic unsteady filtration theory, nonlinear mathematical models of the steady and unsteady flow of single phase as well as horizontal well flow and oil-water two phases flow are deduced with the influence of nonlinear factors including threshold pressure gradient and media deformation. The influences of nonlinear factors upon well deliverability and reservoir pressure distribution as well as the saturation variation pattern of oil-water front are analyzed. By means of the researches such as reasonable well pattern, reasonable well array ration, artificial fracture length optimization advisable water flood timing and feasibility of advanced water flooding, it is necessary to find out effective techniques in order to improve development result of this kind of reservoir. This research result develops and improves on low-velocity nonlinear seepage theory, and offers ways to study similar kind of reservoir; it is meaningful to the development of the ultra-low permeability oil and gas reservoir.

油气运聚动力学的模拟分析——以准噶尔盆地为例

The petroleum migration, happening in the geologic past, is the very important and complex dynamic processes in the petroleum systems. It plays a linking role among all static factors in a system. The accumulation is in fact the result of the petroleum migration. For the petroleum geology, the dynamics research of the petroleum migration refers to the mechanism and process research, as well as the use of the quantitative methods. In this thesis, combining with the qualitative analysis and quantitative modeling, the author manages to discuss theoretically some key problems dealing with migration processes, which have not been solved yet, and to apply the studied results in petroleum system analysis in actual basins. The basin analysis offers the base of the numerical modeling for geological phenomena occurring in sedimentary basins, that consists of the sedimentary facies analysis, the section reconstructing technique, eroded thickness estimating, etc. The methods to construct the geologic model, which is needed in the research of oil and gas migration and accumulation, are discussed. The basin analysis offers also the possibility for the latter modeling works to get and select the parameters, such as stratum's thickness, age, stratigraphy etc. Modeling works were done by using two basin modeling softwares: Basin_Mod and TPC_Mod. The role of compaction during the secondary migration and the heterogeneity of migrating paths within the clastic carrier are modeled. And the conclusions were applied in the migration studies in the Jungaer Basin, lying on the Northwest part of the China. To construct a reliable migration model, the author studied the characteristics of the sedimentation, the pore fluid pressure evolution, as well as the distribution and the evolution of fluid potential, following the tectonic evolution of the Jungaer Basin. The geochemical prospecting results were used to evidence and to calibrate the migration processes: the oil-source correlation, the distribution of the properties of oil, gas and water. Finally, two important petroleum systems, Permian one and Jurassic one were studied and identified, according, principally, to the studies on the petroleum migration within the Jungaer Basin. Since the oil, as well as the gas, moves mainly in separate phase during the secondary migration, their migrating behaviors would be determined by the dynamics conditions of migration, including the driving forces and pathways. Based on such a consideration, the further understandings may be acquired: the roles played by permeable carriers and low-permeable source rock would be very different in compaction, overpressure generation, petroleum migration, and so on. With the numerical method, the effect of the compaction on the secondary migration was analyzed and the results show that the pressure gradient and the flux resulted from compaction are so small that could be neglected by comparing to the buoyancy of oil. The main secondary migration driving forces are therefore buoyancy and capillary within a hydrostatic system. Modeling with the commercial software-Basin_Mod, the migration pathways of petroleum in clastic carriers seem to be inhomogeneous, controlled by heterogeneity of the driving force, which in turn resulted from the topography of seals, the fabrics and the capillary pressure of the clastic carriers. Furthermore, the direct and indirect methods to study fault-sealing properties in the course of migration were systemically summarized. They may be characterized directly by lithological juxtaposition, clay smear and diagenesis, and indirectly the comparing the pressures and fluid properties in the walls at two apartments of a fault. In Jungaer Basin, the abnormal pressures are found in the formations beneath Badaowan or Baijantan Formation. The occurrence of the overpressure seems controlled by the stratigraphy. The rapid sedimentation, tectonic pressuring, clay sealing, chemical diagensis were considered as the principal pressuring mechanisms. The evolution of fluid pressure is influenced differently at different parts of the basin by the tectonic stresses. So the basin appears different pressure evolution cycles from each part to another during the geological history. By coupling the results of thermal evolution, pressure evolution and organic matter maturation, the area and the period of primary migration were acquired and used to determine the secondary migration time and range. The primary migration in Fengcheng Formation happened from latter Triassic to early Jurassic in the main depressions. The main period of lower-Wuerhe Formation was at latter Jurassic in Changji, Shawan and Pen-1-jing-xi Depression, and at the end of early Cretaceous in Mahu Depression. The primary migration in Badaowan and Sangonghe Formation is at the end of early-Cretaceous in Changji Depression. After then, the fluid potential of oil is calculated at the key time determined from area and time of the primary migration. Generally, fluid potential of oil is high in the depressions and low at the uplifts. Synthetically, it is recognized that the petroleum migration in the Jungaer Basin is very complex, that leads us to classify the evolution of petroleum systems in Northwestern China as a primary stage and a reformed one. The remigration of accumulated petroleum, caused by the reformation of the basin, results in the generation of multiple petroleum systems. The faults and unconformities are usually the linkers among the original petroleum systems. The Permian petroleum system in Jungaer Basin is such a multiple petroleum system. However, the Jurassic petroleum system stays still in its primary stage, thought the strong influences of the new tectonic activities.

河流成因储层沉积微相与剩余油分布及形成机理研究

Based on the study of fluvial sandstone reservoir in upper of Guantao group in Gudao and Gudong oilfields, this paper first introduces A.D.Miall's(1996a) architectural-element analysis method that was summarized from ground outcrop scale into the reservoir formation research of the study area, more subtly divides sedimentary microfacies and establishes sedimentary model of research area.on this base, this paper summarizes the laws of residual oil distribution of fluvial formation and the control effect of sedimentary microfacies to residual oil distribution, and reveals residual oil formation mechanism. These results have been applied to residual oil production, and the economic effect is good. This paper will be useful for residual oil research and production and enhancement of oil recovery in similar reservoir. The major conclusions of this paper are as follows. 1. Using the architectural-element analysis method to the core data, a interfacial division scheme of the first to the dixth scale is established for the studied fluvial formation. 2.Seven architectural-elements are divided in upper of Guantao group of study area. The sandstone group 5～1+2 of Neogene upper Gutao group belongs to high sinuous fine grain meandering river, and the sandstone group 6 is sandy braided river. 3. Inter layer, the residual oil saturation of "non-main layer" is higher than "main layer", but the residual recoverable reserve of former is larger. Therefore, "main layer" is the main body of residual oil distribution. The upper and middle part of inner layer has lower permeability and strong seeping resistance. Addition to gravity effect in process of driving, its driving efficiency is low; residual oil saturation is high. Because of controlling of inside non-permeable interlayer or sedimentary construction, the residual oil saturation of non-driving or lower driving efficiency position also is high. On plane, the position of high residual oil saturation mostly is at element LV, CS, CH (FF), FF etc, Which has lower porosity and permeability, as well as lens sand-body and sand-body edge that is not controlled by well-net, non-perfect area of injection and production, lower press difference resort area of inter-well diffiuent-line and shelter from fault, local high position of small structure. 4.Microscopic residual oil mainly includes the non-moved oil in the structure of fine pore network, oil in fine pore and path, oil segment in pore and path vertical to flow direction, oil spot or oil film in big pore, residual oil in non-connective pore. 5.The most essential and internal controlling factor of fluvial formation residual oil distribution is sedimentary microfacies. Status of injection and production is the exterior controlling factor of residual oil distribution. 6. The controlling effect of formation sedimentary microfacies to residual oil distribution indicates inter-layer vertical sedimentary facies change in scale of injection and production layer-series, planar sedimentary face change and inner-layer vertical sedimentary rhythm and interbed in single layer to residual oil distribution. 7. It is difficult to clear up the inter-layer difference in scale of injection and production layer-series. The using status of minor layer is not good and its residual oil saturation is high relatively. It is obvious that inter-layer vertical sedimentary facies changes control inter-layer residual oil distribution at the same or similar conditions of injection and production. For fluvial formation, this vertical sedimentary facies change mainly is positive gyration. Namely, from down to top, channel sediment (element CHL, LA) changes into over-bank sediment (element LV, CR, CS). 8. In water-injection developing process of transverse connecting fluvial sandstone oil formation, injection water always comes into channel nearby, and breaks through along channel and orientation of high pressure gradient, does not expand into side of channel until pressure gradient of channel orientation changes into low. It brings about that water-driving status of over-bank sedimentary element formation (LV, CR, CS) is not good, residual oil saturation is high. In non-connective abandoned channel element (CH) formation with channel, because this reverse is difficult to control by injection and production well-series, its using status is not good, even terribly not good, residual oil is enrichment. 9. The rhythm and sedimentary structure, sedimentary facies change in single sand body brings about vertical changes of formation character, growth character of inner layer interbed. These are important factor of controlling and affecting vertical water spread volume and inner layer residual oil forming and distribution in single sand body. Positive rhythm, is the principal part of fluvial sandstone inner layer sedimentary rhythm. Namely, from down to upside, rock grain granularity changes from coarse to fine, seeping ability changes from strong to feebleness. It brings about that water-driving status of inner layer upside is not good, residual oil saturation is high. Inner layer interbed has different degree affecting and controlling effect to seeping of oil and water. Its affecting degree lies on interbed thickness, extending scale, position, and jeted segment of production or injection well. The effect of interbed at upside of oil formation to oil and water seeping is less; the effect of interbed at middle of oil formation to oil and water seeping is more. 10. Indoor experiment and research indicate that wettability, permeability step, vertical permeability, position of Kmax and ratio of oil viscousity and water viscousity all have great effect on the water-driving recovery ratio. 11. Microscopic residual oil distribution is affected and controlled by formation pore network structure, pressure field distribution, and oil characteristic. 12.The residual oil forming mechanism: the over-bank sedimentary element and upper part of a positive rhythm sandstone have fine pore and throat network, permeability is low, displacement pressure of pore and throat is high. The water-driving power usually falls short of displacement pressure that brings about injection water does not spread into these pore and throat network, thereby immovable oil area, namely residual oil, is formed. At underside of channel sedimentary element and positive rhythm sandstone, porosity and permeability is relatively high, connecting degree of pore and throat is high, displacement pressure of pore and throat is low. Thereby injection water is easy to enter into pore and throat, driving oil in them. Because the pore space is irregular, the surface of pore wall is coarse and non-flat. That the oil locate on concave hole of pore wall and the dead angle of pore, and the oil attaches on surface of pore wall by surface tension, are difficult to be peeled off, becoming water-driving residual oil (remaining oil). On the other hand, Because flowing section lessens, flowing resistance increase, action of capillary fore, or seeping speed decreases at process of transfer at pass narrow throat path in the course carried by driving water. The "oil drop", "oil bead", or "oil segment" peeled off by driving water is difficult to carry and to drive out by water at less pressure difference. Thereby they are enclosed in pore to form discontinuous residual oil. 13.This results described above have been applied in nine develop blocks of Gudao and Gudong oilfield. Its applying effect is marked through local injection production adjustment, deploying replacement well, repair hole, replacement envelop, block off water and profile control etc. Relative method and technology can be applied to other oil production area of Shengli oilfield, and obtain better economic and societal effect.

Perovskite-type B-site Bi-doped ceramic membranes for oxygen separation

Novel mixed conducting oxides, B-site Bi-doped perovskites were exploited and synthesized. Cubic perovskite structures were formed for BaBi0.2COyFe0.8-yO3-delta (y less than or equal to 0.4) and BaBixCo0.2Fe0.8-xP3-delta (x=0.1-0.5) The materials exhibited considerable high oxygen permeability at high temperature. The oxygen permeation flux of BaBi0.2Co0.35Fe0.45O3-delta membrane reached about 0.77 x 10(-6) mol/cm(2) s under an air/helium oxygen partial pressure gradient at 900 degrees C, which was much higher than that of other bismuth-contained mixed conducting membranes. The permeation fluxes of the materials increased with the increase of cobalt content, but no apparent simple relationship was found with the bismuth content. The materials also demonstrated excellent reversibility of oxygen adsorption and desorption. Stable time-related oxygen permeation fluxes were found for BaBi0.2CO0.35Fe0.45O3-delta and BaBi0.3Co0.2Fe0.5O3-delta a membranes at 875 degrees C.

Generation of long, laminar plasma jets at atmospheric pressure and effects of flow turbulence

Long, laminar plasma jets at atmospheric pressure of pure argon and a mixture of argon and nitrogen with jet length up to 45 fi,Hes its diameter could be generated with a DC are torch by! restricting the movement of arc root in the torch channel. Effects of torch structure, gas feeding, and characteristics of power supply on the length of plasma jets were experimentally examined. Plasma jets of considerable length and excellent stability could be obtained by regulating the generating parameters, including are channel geometry gas flow I ate, and feeding methods, etc. Influence of flow turbulence at the torch,nozzle exit on the temperature distribution of plasma jets was numerically simulated. The analysis indicated that laminar flow plasma with very low initial turbulent kinetic energy will produce a long jet, with low axial temperature gradient. This kind of long laminar plasma jet could greatly improve the controllability for materials processing, compared with a short turbulent are let.

Filamentation control in the temperature gradient argon gas

A novel technique of controlling the evolution of the filamentation was experimentally demonstrated in an argon gas-filled tube. The entrance of the filament was heated by a furnace and the other end was cooled with air, which resulted in the temperature gradient distribution along the tube. The experimental results show that multiple filaments are merged into a single filament and then no filament by only increasing the temperature at the entrance of the filament. Also, the filament can appear and disappear after increasing the local temperature and input pulse energy in turn. This technique offers another degree of freedom to control the filamentation and opens a new way for multi-mJ level monocycle pulse generation through filamentation in the noble gas.

Investigation of Interfacial Tensions for Carbon Dioxide Aqueous Solutions by Perturbed-Chain Statistical Associating Fluid Theory Combined with Density-Gradient Theory

The perturbed-chain statistical associating fluid theory and density-gradient theory are used to construct an equation of state (EOS) applicable for the phase behaviors of carbon dioxide aqueous solutions. With the molecular parameters and influence parameters respectively regressed from bulk properties and surface tensions of pure fluids as input, both the bulk and interfacial properties of carbon dioxide aqueous solutions are satisfactorily correlated by adjusting the binary interaction parameter (k(ij)). Our results show that the constructed EOS is able to describe the interfacial properties of carbon dioxide aqueous solutions in a wide temperature range, and illustrate the influences of temperature, pressure, and densities in each phase on the interfacial properties.

2-(2-Phenyl-1H-phenanthro-[9,10-d]imidazole-1-yl)-acetic acid (PPIA) and its application for determination of amines by high performance liquid chromatography with fluorescence detection and identification with mass spectroscopy/atmospheric pressure chemical ionization

A simple, sensitive, and mild method for the determination of amino compounds based on a condensation reaction with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC-HCI) as the dehydrant with fluorescence detection has been developed. Amines were derivatized to their acidamides with labeling reagent 2-(2-phenyl-1H-phenanthro-[9,10-d]imidazole-1-yl)-acetic acid (PPIA). Studies on derivatization conditions indicated that the coupling reaction proceeded rapidly and smoothly in the presence of a base catalyst in acetonitrile to give the corresponding sensitively fluorescent derivatives with an excitation maximum at lambda(ex) 260nm and an emission maximum at lambda(em) 380nm. The labeled derivatives exhibited high stability and were enough to be efficiently analyzed by high-performance liquid chromatography. Identification of derivatives was carried out by online post-column mass spectrometry (LC/APCI-MS/MS) and showed an intense protonated molecular ion corresponding m/z [MH](+) under APCI in positive-ion mode. At the same time, the fluorescence properties of derivatives in various solvents or at different temperature were investigated. The method, in conjunction with a gradient elution, offered a baseline resolution of the common amine derivatives on a reversed-phase Eclipse XDB-C-8 column. LC separation for the derivatized amines showed good reproducibility with acetonitrile-water as mobile phase. Detection limits calculated from 0.78 pmol injection, at a signal-to-noise ratio of 3, were 3.1-18.2 fmol. The mean intra- and inter-assay precision for all amine levels were < 3.85% and 2.11%, respectively. Excellent linear responses were observed with coefficients of > 0.9996. The established method for the determination of aliphatic amines from real wastewater and biological samples was satisfactory. (c) 2006 Elsevier B.V. All rights reserved.

Effect of ambient pressure and radiation reabsorption of atmosphere on the flame spreading over thermally thin combustibles in microgravity

For the flame spread over thermally thin combustibles in an atmosphere, if the atmosphere cannot emit and absorb the thermal radiation (e.g. for atmosphere Of O-2-N-2), the conductive heat transfer from the flame to the fuel surface dominates the flame spread at lower ambient atmosphere. As the ambient pressure increases, the flame spread rate increases, and the radiant heat transfer from the flame to the fuel surface gradually becomes the dominant driving force for the flame spread. In contrast, if the atmosphere is able to emit and absorb the thermal radiation (e.g. for atmosphere Of O-2-CO2), at lower pressure, the heat transfer from flame to the fuel surface is enhanced by the radiation reabsorption of the atmosphere at the leading edge of the flame, and both conduction and thermal radiation play important roles in the mechanism of flame spread. With the increase in ambient pressure, the oxygen diffuses more quickly from ambient atmosphere into the flame, the chemical reaction in the flame is enhanced, and the flame spread rate increases. When the ambient pressure is greater than a critical value, the thermal radiation from the flame to the solid surface is hampered by the radiation reabsorption of ambient atmosphere with the further increase in ambient pressure. As a result, with the increase in ambient pressure, the flame spread rate decreases and the heat conduction gradually dominates the flame spread over the fuel surface.

Pressure Drop of Bubbly Two-Phase Flow in a Square Channel at Reduced Gravity

A new set of experimental pressure drop data, collected aboard the Russian IL-76MDK, is reported for bubbly airwater two-phase flow in a square channel with a cross-sectional area of 12x 12mm(2). The present data are compared to several frequently used empirical models, e.g. homogeneous model, Lockhart-Martinelli-Chisholm correlation and Friedel's model. It is shown that the predictions of the models mentioned above are generally not satisfied. A new homogeneous model is developed based on the analysis of the characteristics of bubbly two-phase flow at reduced gravity. It is tested with the present data and other data collected by other researchers in circular pipes. Some questions related to the present model are also discussed. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Wave Propagation Analysis in a Pressure-Wave-Refrigerator

Pressure wave refrigerators (PWR) refrigerate the gas through periodical expansion waves. Due to its simple structure and robustness, PWR may have many potential applications if the efficiency becomes competitive with existing alternative devices. In order to improve the efficiency, the characteristics of wave propagation in a PWR are studied by experiment, numerical simulation and theoretical analysis. Based on the experimental results and numerical simulation, a simplified model is suggested, which includes the assumptions of flux-equilibrium and conservation of the free energy. This allows the independent analysis of the operation parameters and design specifics. Furthermore, the optimum operation condition can be deduced. Some considerations to improve the PWR efficiency are also given.

The Liquefaction and Displacement of Highly Saturated Sand under Water Pressure Oscillation

In order to investigate the characteristics of water wave induced liquefaction in highly saturated sand in vertical direction, a one-dimensional model of highly saturated sand to water pressure oscillation is presented based oil the two-phase continuous media theory. The development of the effective stresses and the liquefaction thickness are analyzed. It is shown that water pressure oscillating loading affects liquefaction severely and the developing rate of liquefaction increases with the decreasing of the sand strength or the increasing of the loading strength. It is shown also that there is obvious phase lag in the sand Column. If the sand permeability is non-uniform, the pore pressure and the strain rise sharply at which the smallest permeability occurs. This solution may explain Why the fracture occurs in the sand column in some conditions.

Characteristics of Argon Laminar DC Plasma Jet at Atmospheric Pressure

利用特殊设计的等离子体发生器,选择等离子体产生的工艺参数,实现工艺过程的精确控制,在大气压环境下获得了性能稳定的氖气直流层流等离子体射流。与湍流等离子体射流长度较短、径向尺寸较大、工作噪音高等特点相比,层流等离于体射流长度可达到550mm,而且沿整个射流长度其径向尺寸维持不变,工作噪音很小。当气流量为120cm~3/s、弧电流在70-200A的范围时,射流长度随弧电流的增加而增加,热效率起初略有降低然后维持平稳。随气流量的增加,层流等离子体射流的热效率也增加,在弧电流为200A时,可以达到40%。实验中测