34 resultados para Experimental methods


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Natural fluids with water-salt-gas are often found in every sphere of the Earth, whose physicochemical properties and geochemical behaviors are complicated. To study these properties and behaviors turns out to be one of the challenging issues in geosciences. Traditional approaches mainly depend on experiments and observations. However, it is impossible to obtain a large number of data covering a large T-P space of the Earth by experimental methods in the near future, which will hinder the advance of the theoretical study. Therefore, it is important to model natural fluids by advanced theoretical methods, by which limited experimental data can be extended to a large temperature-pressure-composition space. Physicochemical models developed in this dissertation are not only more accurate, but also extend the applied T-P-m region of the experimental data of the multi-fluid systems by about two times. These models provide the new and accurate theoretical tools for the geochemical research, especially for the water-rock interactions and the study of the fluid inclusions. The main achievements can be summarized as follows: (1) A solubility model on components of natural gases is presented. The solubility model on the systems of CH4-H2O-NaCl, C2H6-H2O-NaCl or N2-H2O-NaCl takes advantage of modern physicochemical theory and methods, and is an improvement over previous models whose prediction and precision are relatively poor. The model can predict not only the gas solubility in liquid phase but also water content in the gas phase. In addition, it can predict gases (methane or nitrogen) solubility in seawater and brine. Isochores can be determined, which are very important in the interpretation of fluid inclusions. (2) A density model on common aqueous salt solutions is developed. The density models with high precision for common aqueous salt solutions (H2O-NaCl, H2O-LiCl, H2O-KCl, H2O-MgCl2, H2O-CaCl2, H2O-SrCl2 or H2O-BaCl2) are absent in the past. Previous density models are limited to the relatively small range of experimental data, and cannot meet the requirement of the study of natural fluids. So a general density model of the above systems is presented by us based on the international standard density model of the water. The model exceeds the other models in both precision and prediction. (3) A viscosity model on common aqueous alkali-chloride solutions is proposed. Dynamic viscosity of water-salt systems, an important physics variable, is widely used in three-dimension simulation of the fluids. But in most cases, due to the lack of viscosity models with a wide T-P range, the viscosity of aqueous salt solutions is replaced by that of the water, giving rise to a relatively large uncertainty. A viscosity model with good prediction for the systems (H2O-NaCl, H2O-LiCl or H2O-KCl) is presented on the base of the international standard viscosity model of water and the density model developed before. (4) Equation of State applied in fluid inclusions. The best Equations of State in the world developed by others or us recently are applied in the study of the fluid inclusions. Phase equilibria and isochores of unitary system (e.g. H2O, CO2, CH4, O2, N2, C2H6 or H2S), binary H2O-NaCl system and ternary H2O-CH4-NaCl system are finished. From these programs and thermodynamic equations of coexisting ores, the physicochemical conditions before or after the deposits form can be determined. To some extent, it is a better tool.

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Self-conscious emotions (guilt, shame, embarrassment, pride, etc) are social emotions, and involve complex appraisals of how one’s behavior has been evaluated by the self and other people according to some value standards. Self-conscious emotions play an important role in human life by arousing and regulating human action tendencies, feeling and thoughts, which can promote people to work hard in achievement and task fields, maintain good interpersonal relationship according with social morality and expectation. The present study aimed to examine complex self-conscious emotional understanding capabilities in junior middle school students with and without learning disabilities, how the self-conscious emotions generate, and relationship between self-conscious emotions and self-representation in academic and interpersonal fields. Situational experimental methods were used in this research, and the results would give further supports for learning disabilities intervention. The main results of present research are as follows. 1. The study included 4 parts and 6 experiments. The aim of study 1 was to explore whether juveniles with learning disabilities understood complex self-conscious emotions differently from juveniles without learning disabilities. We surveyed the self-conscious emotions understanding of 37 learning disabilities and 45 non-learning disabilities with the emotional situation stories. The results indicated that the self-conscious emotional recognition in others for learning disabilities was lower than that of non-learning disabilities in different emotional recognition tasks. Moreover, children with learning disabilities were more inclined to recognize emotions in themselves as elemental emotions, however, children without learning disabilities were more inclined to recognize emotions in themselves as self-conscious emotions. 2. The aim of study 2 was to explore the generative mechanism of self-conscious emotions in academic and interpersonal fields with the method of situational experiments, namely to examine whether the self-discrepancy could cause self-conscious emotions for learning disabilities. 84 learning disabilities (in experiment 1) and 80 learning disabilities (in experiment 2) participated in the research, and the results were as follows. (1) Self discrepancy caused participants’ self-conscious emotions effectively in academic and interpersonal fields. One’s own and parents’ perspercive on the actual-ideal self-discrepancy both produced dejection-related emotions (shame、embarrassment) and agitation-related emotions (guilt). (2)In academic fields, children with learning disabilities caused higher level negative self-conscious emotions (embarrassment, shame, and guilt) and lower level positive self-conscious emotion (pride). However, there were no differences of self-conscious emotions for children with and without learning disabilities in non-academic fields. 3. The aim of study 3 was to explore what influence had self-conscious emotions on self-representation for learning disabilities with the method of situational experiments. 57 learning disabilities (in experiment 1) and 67 learning disabilities (in experiment 2) participated in the research, and the results were as follows. (1)The negative self-conscious for learning disabilities could influence their positive or negative academic and positive interpersonal self-representation stability, the ways in which self-evaluation of ability mediate these effects. However, there was no significant effect for the negative self-conscious and self-evaluation of ability predicting negative interpersonal self-representation stability. (2)The stability level of positive academic and interpersonal self-representation for learning disabilities was lower than that of non-learning disabilities. There was no significant difference of the negative interpersonal self-representation stability for children with and without learning disabilities in the positive self-conscious valence condition. However, the stability level of negative interpersonal self-representation for learning disabilities was lower than that of non-learning disabilities in the negative self-conscious valence condition. 4. The aim of study 4 was to explore the intervention effects for self-conscious emotions training course on emotional comprehension cability. 65 learning disabilities (34 in experimental group, and 31 in control group) participated in the research. The results showed that self-conscious emotions course boosted the self-conscious emotions apprehensive level for children with learning disabilities.

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Recently, as a moral affect and trait, gratitude has been acquiring growing attention in social psychology. Previous research showed those who are grateful were motivated not only to reciprocate the benefactor, but also to make altruistic behavior towards other people. By reviewing previous studies, we found two approaches on exploring the gratitude-altruism link: one is to examine the relationship of correlation between gratitude being a personality trait and altruistic tendency using questionnaires as research method; another is to probe into the causality of gratitude and altruistic behaviors by experimental methods. The present research consists of five studies combining correlative studies and experimental designs, trying to explore the effect of gratitude on altruistic tendency and altruistic behavior from perspective of trait and situation. Participants are 1769 Chinese undergraduates and 332 community residents. Firstly, results of study one showed dispositional gratitude was significantly positively correlated with altruistic tendency: higher dispositional gratitude, higher altruistic tendency. When social desirability, Big Five, and grateful mood were controlled, the correlation of gratitude and altruism still remained relatively significant. Secondly, results of the most experiments showed: main effects of both dispositional gratitude and situational gratitude were significant. For example, people with high dispositional gratitude showed higher altruistic tendency than people with low dispositional gratitude; People in high condition of gratitude arousing showed higher altruistic tendency than people in low condition of gratitude arousing as well as the control group. Thirdly, data analyses showed that the interaction effect of dispositional gratitude and situational gratitude on general altruistic tendency and altruistic behavior was significant. Compared with people with high dispositional gratitude, those with low dispositional gratitude was relatively more sensitive to condition of gratitude arousing. The latter show enhanced altruistic tendency in condition of gratitude arousing than in control condition. This interaction effect was also represented in three different condition of altruistic behavior. (1) As for beneficiaries of altruistic behavior, people with low dispositional gratitude showed enhanced altruistic behavior in condition of gratitude arousing towards strangers rather than friends and relatives. (2) As for the receiver role of altruistic behavior, people with low dispositional gratitude showed less “reject” or more “acceptance” in condition of gratitude arousing than that of the control condition. (3) When it comes to the cost of altruistic behavior, people with low dispositional gratitude showed enhanced altruistic tendency in condition of gratitude arousing than that of the control condition. However, altruistic behaviors of high cost in real life were more affected by dispositional gratitude.

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The space experimental device for testing the Marangoni drop migrations has been discussed in the present paper. The experiment is one of the spaceship projects of China. In comparison with similar devices, it has the ability of completing all the scientific experiments by both auto controlling and telescience methods. It not only can perform drop migration experiments of large Reynolds numbers but also has an equi-thick interferential system.

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In this paper, a series of experiments have been conducted in a U-shaped oscillatory flow tunnel, which provides a more realistic simulation than the previous actuator loading methods. Based on the experimental data of pipe displacement with two different constraint conditions (freely laid pipelines and anti-rolling pipelines), three characteristic times in the process of pipeline losing stability are identified. The effects of sand size on the pipeline lateral stability are examined for freely laid pipelines. The empirical relationships between non-dimensional pipeline weight (G) and Fronde number (Fr-b) are established for different constraint conditions, which will provide a guide for engineering practice. (C) 2002 Elsevier Science Ltd. All rights reserved.

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In this paper, we study the issues of modeling, numerical methods, and simulation with comparison to experimental data for the particle-fluid two-phase flow problem involving a solid-liquid mixed medium. The physical situation being considered is a pulsed liquid fluidized bed. The mathematical model is based on the assumption of one-dimensional flows, incompressible in both particle and fluid phases, equal particle diameters, and the wall friction force on both phases being ignored. The model consists of a set of coupled differential equations describing the conservation of mass and momentum in both phases with coupling and interaction between the two phases. We demonstrate conditions under which the system is either mathematically well posed or ill posed. We consider the general model with additional physical viscosities and/or additional virtual mass forces, both of which stabilize the system. Two numerical methods, one of them is first-order accurate and the other fifth-order accurate, are used to solve the models. A change of variable technique effectively handles the changing domain and boundary conditions. The numerical methods are demonstrated to be stable and convergent through careful numerical experiments. Simulation results for realistic pulsed liquid fluidized bed are provided and compared with experimental data. (C) 2004 Elsevier Ltd. All rights reserved.

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The transition processes from steady flow into oscillatory flow in a liquid bridge of the half floating zone are studied experimentally. Two methods of noncontacted diagnoses are developed to measure the distribution of critical Marangoni numbers described by the onset of the oscillation st the free surface of the liquid bridge.The experimental results obtained for both cases of the upper rod heated and the lower rod heated agree with the prediction by Rayleigh's instability theory.The sensitive relations between the relatively fat or slender liquid bridge and the onset of oscillatory convection are also discussed to reveal the insight of the pressure distribution near the free surface. The experiments have been performed in a small liquid bridge, where the Bond number is much smaller than 1, and the results can be used to simulate the experiment in the microgravity environment.

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Validated by comparison with DNS, numerical database of turbulent channel flows is yielded by Large Eddy Simulation (LES). Three conventional techniques: uv quadrant 2, VITA and mu-level techniques for detecting turbulent bursts are applied to the identification of turbulent bursts. With a grouping parameter introduced by Bogard & Tiedemann (1986) or Luchik & Tiederman (1987), multiple ejections detected by these techniques which originate from a single burst can be grouped into a single-burst event. The results are compared with experimental results, showing that all techniques yield reasonable average burst period. However, uv quadrant 2 and mu-level are found to be superior to VITA in having large threshold-independent range.

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In this study, the vortex-induced vibrations of a cylinder near a rigid plane boundary in a steady flow are studied experimentally. The phenomenon of vortex-induced vibrations of the cylinder near the rigid plane boundary is reproduced in the flume. The vortex shedding frequency and mode are also measured by the methods of hot film velocimeter and hydrogen bubbles. A parametric study is carried out to investigate the influences of reduced velocity, gap-to-diameter ratio, stability parameter and mass ratio on the amplitude and frequency responses of the cylinder. Experimental results indicate: (1) the Strouhal number (St) is around 0.2 for the stationary cylinder near a plane boundary in the sub-critical flow regime; (2) with increasing gap-to-diameter ratio (e (0)/D), the amplitude ratio (A/D) gets larger but frequency ratio (f/f (n) ) has a slight variation for the case of larger values of e (0)/D (e (0)/D > 0.66 in this study); (3) there is a clear difference of amplitude and frequency responses of the cylinder between the larger gap-to-diameter ratios (e (0)/D > 0.66) and the smaller ones (e (0)/D < 0.3); (4) the vibration of the cylinder is easier to occur and the range of vibration in terms of V (r) number becomes more extensive with decrease of the stability parameter, but the frequency response is affected slightly by the stability parameter; (5) with decreasing mass ratio, the width of the lock-in ranges in terms of V (r) and the frequency ratio (f/f (n) ) become larger.

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A set of experimental system to study hydrate dissociation in porous media is built and some experiments on hydrate dissociation by depressurization are carried out. A mathematical model is developed to simulate the hydrate dissociation by depressurization in hydrate-bearing porous media. The model can be used to analyze the effects of the flow of multiphase fluids, the kinetic process and endothermic process of hydrate dissociation, ice-water phase equilibrium, the variation of permeability, convection and conduction on the hydrate dissociation, and gas and water productions. The numerical results agree well with the experimental results, which validate our mathematical model. For a 3-D hydrate reservoir of Class 3, the evolutions of pressure, temperature, and saturations are elucidated and the effects of some main parameters on gas and water rates are analyzed. Numerical results show that gas can be produced effectively from hydrate reservoir in the first stage of depressurization. Then, methods such as thermal stimulation or inhibitor injection should be considered due to the energy deficiency of formation energy. The numerical results for 3-D hydrate reservoir of Class 1 show that the overlying gas hydrate zone can apparently enhance gas rate and prolong life span of gas reservoir.

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Based on the conventional through-short-match (TSM) method, an improved TSM method has been proposed in this Letter. This method gives an analytical solution and has almost all the advantages of conventional TSM methods. For example, it has no phase uncertainty and no bandwidth limitation. The experimental results show that the accuracy can be significantly improved with this method. The proposed theory can be applied to the through-open-match (TOM) method. (C) 2002 Wiley Periodicals. Inc.

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The guide mode whose frequency locates in the band edge in photonic crystal single line defect waveguide has very low group velocity. So the confinement and gain of electromagnetic field in the band edge are strongly enhanced. Photonic crystal waveguide laser is fabricated and the slow light phenomenon is investigated. The laser is pumped by pulsed pumping light at 980nm whose duty ratio is 0.05%. The active layer in photonic crystal slab is InGaAsP multiple quantum well. Light is transimited by a photonic crystal chirp waveguide in one facet of the laser. Then the output light is coupled to a fiber and the character of laser is analysis by an optical spectrometer. It is found that single mode and multimode happens with different power of pumping light. Meanwhile the plane wave expansion and finite-difference time-domain methods are used to simulate the phenomenon of slow light. And the result of the experiment is compared with the theory which proves the slow light results in lasing oscillation.

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The technology of "explosion in fractures" is one of new synthetic engineering methods used in low permeability reservoirs. The most important problem arose from the technology is to assess the deflagration propagation capability of milky explosives in rock fractures. In order to investigate detailed this problem in the laboratory, an experimental setup was designed and developed in which different conditions can be simulated. The experimental setup mainly includes two parts. One is the experimental part and the other is the measurement part. In the experimental setup, the narrow slots with different width can be simulated; meanwhile, different initial pressures and initial temperatures can be loaded on the explosives inside the narrow slots. The initial pressure range is from 0-60 MPa, and the initial temperatures range is from room temperature to 100 V. The temperature and the velocity of deflagration wave can be measured; meanwhile the corresponding pressure in the narrow slot is also measured. In the end, some typical measurement results are briefly presented and discussed.

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Silicon-on-insulator (SOI) technologies have been developed for radiation-hardened military and space applications. The use of SOI has been motivated by the full dielectric isolation of individual transistors, which prevents latch-up. The sensitive region for charge collection in SOI technologies is much smaller than for bulk-silicon devices potentially making SOI devices much harder to single event upset (SEU). In this study, 64 kB SOI SRAMs were exposed to different heavy ions, such as Cu, Br, I, Kr. Experimental results show that the heavy ion SEU threshold linear energy transfer (LET) in the 64 kB SOI SRAMs is about 71.8 MeV cm(2)/mg. Accorded to the experimental results, the single event upset rate (SEUR) in space orbits were calculated and they are at the order of 10(-13) upset/(day bit).