充气水泥浆防止失重的室内研究

分析了水泥浆失重的主要原因及充气水泥浆防止失重的机理,并在室内进行了模拟实验,探讨了充气水泥浆的各种性能。分析表明,当失重产生时。充气水泥浆上部的浆柱自重和结构力形成了“塞子”,充气水泥浆发气,使之憋上一个附加压力,补偿因胶凝失重或桥堵失重而降低的压力,而且充气水泥浆的发气量必须满足:浆柱有效压力和气体产生的附加压力大于地层压力.实验结果还表明,充气水泥浆不但能防止油、气、水窜,还能满足固井施工和固井质量的要求。     

Modeling high pressure inactivation of <Emphasis Type="Italic">Escherichia coli</Emphasis> and <Emphasis Type="Italic">Listeria innocua</Emphasis> in whole milk

The survival curves of Escherichia coli and Listeria innocua inactivated by high hydrostatic pressure (HHP) were obtained at room temperature (∼22 °C) and at five pressure levels (400, 450, 500, 550 and 600 MPa) in whole milk. These curves were described by the Weibull model and parameters of this model were reduced from two to one with slight loss of goodness-of-fit. The logarithm of the time constant parameter (δ) of the reduced Weibull model was described with respect to high pressure (P). This approach can be used to define a z _p value analogous to the modeling of the classical D value (increase in pressure that results in one log unit decrease of δ values). The development of accurate survival models under high pressure, as presented here, can be very beneficial to food industry for designing, evaluating and optimizing HHP processes as a new preservation technology.     

Gas–liquid mass transfer in a new three-phase stirred airlift reactor

The gas–liquid mass transfer performances of a novel three-phase reactor involving both airlift and mechanical stirring have been tested using aqueous solutions of glucose. Stirring in addition to classical airlift leads to an importance increase of k_La. The absolute increase depends mainly on the stirrer speed are not on the gas velocity. A slight effect of the solid loading with a maximum at about 2% (w/v) was observed. Two correlations that show the influence of physical parameters are proposed for both water and glucose solutions. © 1998 SCI     

Synthesis,structural characterization and luminescent properties of Tb3+-doped AgLaP2O7 phosphors

Silver lanthanum diphosphates doped with terbium, AgLa_1-xTb_xP₂O₇ (x=0%, 1%, 5%, 10%, 15% and 20%), were prepared by solid state reaction at T=500°. The obtained compounds were investigated by means of a multi-methodological approach, involving the Scanning Electron Microscopy (SEM) equipped with energy dispersive X-Ray spectroscopy (EDS) for morphological investigation and semi-quantitative chemical analysis, respectively; powder X-ray diffraction (PXRD) for structural characterization and Rietveld refinement; Fourier Transform InfraRed (FTIR) and Raman spectroscopies for qualitative study. Finally, emission spectra were collected in order to detect the fluorescence properties of the compounds.The unit cell parameters and the space group of all the family members were determined by PXRD data. The compounds crystallize in the orthorhombic Pnma space group, with the AgLaP₂O₇ cell constants equal to: a?=?8.6706(1) Å, b?=?5.3218(1) Å, c?=?12.8839(1) Å and cell volume V?=?594.51(1) ų. A decreasing trend for unit cell parameters was observed at increase of dopant concentration. For the pure phase, the investigation was completed with the structure solution via Direct Methods and Rietveld refinement. The crystal structure consists of compact layers of LaO₉ polyhedra, down the c axis, bridged by P₂O₇ diphosphate groups and by zig-zag chains of AgO₉ polyhedra down b.The FTIR and Raman analysis supports the chemical structure, highlighting the deformation (δPO₃) and stretching (νPO₃) vibration of PO₃ groups, and the characteristic bands of P₂O₇^4- groups attributed to the symmetric and asymmetric stretching (ν_s and ν_as) of P-O-P bridge, respectively.The luminescence properties of Tb³⁺ activating ion in AgLa_1-xTb_xP₂O₇ (x=1%, 5%, 10%, 15% and 20%) were also examined. No concentration quenching of the main ⁵D₄-→⁷F₅ emission, responsible for the well known green emission of Tb³⁺ ion, was observed in the studied concentration range, whereas a concentration quenching of the emission from ⁵D₃ level, due to ⁵D₃^-→⁵D₄ cross relaxation process, was revealed.     

三塘湖盆地牛东火山岩处理和测井识别技术研究

由于火山岩以裂缝性储集层为主,其识别与评价一直是油气勘探的难点,本文通过地震波及声波速度分析、地震反射特征分析、三瞬信息分析及测井声波约束反演等技术分别对三塘湖盆地火山岩储集层进行了响应特征研究,为有效圈定和评价火山岩储集性提供了可靠的依据。     

Multi-pulsed high hydrostatic pressure treatment for inactivation and injury of Escherichia coli

Escherichia coli cells in peptone water were pressurized at 300 MPa at ambient temperature with no holding time (pulse series) and with a total holding duration of 300 s for single- (300 s × 1 pulse) and multi-pulsed (150 s × 2 pulses, 100 s × 3 pulses, 75 s × 4 pulses, 60 s × 5 pulses, 50 s × 6 pulses and 30 s × 10 pulses) high hydrostatic pressure (HHP) treatments. Multi-pulsed HHP treatment with no holding time indicated that as the pulse number increased the number of inactivated and injured cells also increased. Holding time had significant effect on the inactivation of E. coli. There was low inactivation difference between single- and multi-pulsed HHP treatments with holding time. Escherichia coli cells showed at least 1.6 log₁₀ more reduction on selective medium than the non-selective medium indicating that more than 95 % of the survivors severely injured for both single- and multi-pulsed treatments with holding time. Although the inactivation difference was low between single- and multi-pulsed HHP treatments, storage at 4 °C revealed that there was less recovery from injury for multi-pulsed HHP treatment.     

油气田合理储采比的确定及应用

储采比是油气田产量保证程度的一种指标，该值越大，产量稳定实现的可能性越高。当储采比低于某一数值时，油田开发即进入递减阶段。为此，在Arps和Logistic产量递减方程理论研究的基础上，分别导出了油田产量遵循不同递减规律时储采比与时间的关系式。在这些关系式中，当t取0时，可直接确定出油田保持稳定是所需的储采比下限值。通过这些研究，为油气田稳产形势的分析、评价以及规划提供了可靠的理论基础。经实例验证，效果很好。     

Wind energy status of Iran: Evaluating Iran's technological capability in manufacturing wind turbines

Iran, as a developing country, will be confronted with a significant increase in electricity demand in future years. Being a petroleum producing country has resulted in extreme subsidies for energy production from fossilized resources such as oil and gas. This issue is one of the most important factors regarding underdevelopment of renewable energies in Iran. Expansive use of fossil resources in providing the necessary energy has resulted in Iran being among the 20 countries that have a share in the 75% spread of greenhouse gases. This issue has resulted in greater attention on behalf of the energy sectors policy makers regarding renewable energies, especially wind. Awareness regarding the current condition of each system is the first step for optimum policy making. On this basis, analyzing Iran's wind conditions and assessing its technological capabilities is considered a pre-requisite for the wind sectors policy making. This paper aims at studying Iran's wind energy status in the form of available capacities, power production, wind power plant characteristics, principal agents and existing protective laws. Also, the main focus of this paper is on evaluating Iran's potential and effective technological capabilities for producing the main parts of wind turbines in different sizes. In order to fulfill this task, sector-level technological capabilities are defined. Then by analyzing active organizations in this field, Iran's capability level will be determined and by comparing it with the ideal conditions, Iran's technological gaps will be identified. The reasons for the creation of such shortcomings will also be introduced from different aspects in the form of the Atlas model. Finally, Iran's potential capabilities in resolving technological shortcomings will be identified.     

Component mode synthesis and polynomial chaos expansions for stochastic frequency functions of large linear FE models

This paper presents a methodological approach for the numerical investigation of frequency transfer functions for large FE systems with linear and nonlinear stochastic parameters. The component mode synthesis methods are used to reduce the size of the model and are extended to stochastic structural vibrations. The statistical first two moments of frequency transfer functions are obtained by an adaptive polynomial chaos expansion. Free and fixed interface methods with and without reduction of interface dof are used. The coupling with the first and second order polynomial chaos expansion is elaborated for beams and assembled plates with linear and nonlinear stochastic parameters.     

A robust study of reliability-based optimization methods under eigen-frequency

Nowadays, the search in reliability-based design optimization is becoming an important engineering design activity. Traditionally for these problems, the objective function is to minimize a cost function while satisfying the reliability constraints. The reliability constraints are usually formulated as constraints on the probability of failure. This paper focuses on the study of a particular problem with the failure mode on vibration of structure. The difficulty in evaluating reliability constraints comes from the fact that modern reliability analysis methods are themselves formulated as an optimization problem. Solving such nested optimization problems is extremely expensive for large-scale multidisciplinary systems which are likewise computationally intensive. With this in mind research, we propose in this paper a new method to treat reliability-based optimization methods under frequencies constraint. The goal of this development has resolved just one problem of optimization and reduced the cost of computation. Aircraft wing design typically involves multiple disciplines such as aerodynamics and structure; this numerical example demonstrated the different advantages of the proposed method.