尾管用内嵌式卡瓦坐挂机构承载能力分析

基于ABAQUS有限元分析软件,建立内嵌式卡瓦尾管悬挂器的力学模型。分析不同工况下卡瓦、外层套管、锥套和本体的应力分布及变形,确定了塑形应变程度,得到了该悬挂器的最大承载力约为2 800 kN。通过理论和数值模拟对比分析,验证数值模拟分析的合理性。为现场应用提供理论依据。     

基于趋势分析的间歇过程异常工况超早期报警研究

为了实现化工间歇过程阶跃变化中异常工况的早期报警,重点监测过程参数的变化趋势,提出基于最小二乘法的拟合 微分 再微分的化工间歇过程趋势分析方法。采用最小二乘法对历史数据进行拟合,依据过程参数的变化趋势,将间歇过程分为3个阶段。对数据微分求导计算,根据得出的过程参数一阶变化率的取值区间进行间歇过程多时段工况识别,针对危险性较大的阶跃变化过程利用再微分计算过程参数的二阶变化率取值区间,结合滑动窗算法,实现连续的间歇过程异常工况早期报警监测。在聚丙烯装置异常工况早期预警案例分析中,以聚合釜升温过程中上温为目标参数,实时监测上温变化趋势,识别间歇过程工况,并且在上温升温速率过快但温度未超出分布式控制系统(Distributed control system, DCS)阈值时发出警报。结果表明,所提出方法能够在参数状态出现异常的早期发出警报,相比于3σ报警阈值的方法提前24 min 34 s报警。     

Investigation of directly suspended droplet micro extraction method for extraction of trihalomethane and halomethane in water samples

Simple and efficient directly suspended droplet micro extraction (DSDME) in conjunction with gas chromatography-electron capture detector (GC-ECD) has been developed for extraction and determination of Halomethane and Trihalomethane from water samples. In this technique a micro drop of n-hexane is delivered to the surface of an aqueous sample while being agitated by a stirring bar in the bulk of solution. Factors relevant to the extraction efficiency were studied and optimized. The optimized extraction conditions were extraction solvent: n- hexane; NaCl concentration: 1 M; solvent extraction volume: 50 μL; stirring rate: 720 rpm and the extraction time: 5 min. The detection limits of the method were in the range of 0.059–0.137 µg L^?1, relative standard deviation (n = 3) range were 0.019–0.048%. A good linearity (r² ≥ 0.997) and a relatively broad dynamic linear range (10–200 µg L^?1) were obtained and recoveries of method were in the range of 97.69–99.51%. Finally, the proposed method was successfully utilized for pre concentration and determination of halo methane in different real samples. Successfully DSDME technique combined with capillary GC-ECD for the analysis of THMs and HMs in the water investigated samples.     

Research on paraffin removal and prevention by Bacillus spp. in high-salinity reservoirs

Problems in paraffin deposition occur frequently in oil exploitation. Considering the problem that some paraffin removal and prevention strains cannot grow in high-salinity reservoirs, we domesticated four salt-tolerant laboratory bacterial strains. Crude oil emulsification effect, paraffin removal rate, and paraffin prevention rate of the strains were evaluated. KB and JH-A strains exhibited good paraffin removal and prevention effects, with paraffin removal rates of 51.82% and 81.56%; and 51.82% and 80.90%, respectively. Gas chromatography mass spectrometry analysis of paraffin components before and after biodegradation was performed on KB and JH-A strains. Results showed that relative contents of n-alkanes between C15–C23 and C27–C30 evidently decreased, indicating their good biodegradation. This technique provides a new method for practical application of paraffin removal and prevention in high-salinity reservoirs.     

Petroleum substitution, greenhouse gas emissions reduction and environmental benefits from the development of natural gas vehicles in China

This study develops a bottom-up model to quantitatively assess the comprehensive effects of replacing traditional petroleum-powered vehicles with natural gas vehicles (NGVs) in China based on an investigation of the direct energy consumption and critical air pollutant (CAP) emission intensity, life-cycle energy use and greenhouse gas (GHG) emission intensity of NGV fleets. The results indicate that, on average, there are no net energy savings from replacing a traditional fuel vehicle with an NGV. Interestingly, an NGV results in significant reductions in direct CAP and life-cycle GHG emissions compared to those of a traditional fuel vehicle, ranging from 61% to 76% and 12% to 29%, respectively. Due to the increasing use of natural gas as a vehicle fuel in China (i.e. approximately 28.2 billion cubic metres of natural gas in 2015), the total petroleum substituted with natural gas was approximately 23.8 million tonnes (Mt), which generated a GHG emission reduction of 16.9 Mt of CO₂ equivalent and a CAP emission reduction of 1.8 Mt in 2015. Given the significant contribution of NGVs, growing the NGV population in 2020 will further increase the petroleum substitution benefits and CAP and GHG emission reduction benefits by approximately 42.5 Mt of petroleum-based fuel, 3.1 Mt of CAPs and 28.0 Mt of GHGs. By 2030, these benefits will reach 81.5 Mt of traditional petroleum fuel, 5.6 Mt of CAPs and 50.5 Mt of GHGs, respectively.     

A new estimating method of minimum miscibility pressure as a key parameter in designing CO2 gas injection process

Minimum miscibility pressure (MMP) is an important key parameter for designing any gas flooding project in enhancing oil recovery, whereas the injection must be operated at or above (MMP). This parameter will be determined before any field trial, because it is important for operator to plan suitable surface facilities and to develop injection conditions. MMP may be reliably estimated by traditional laboratory techniques, which are very costly and time consuming. Various empirical correlations for the estimation of MMP are available in literature however using them is not reliable as each correlation relates to a unique reservoir and fluid conditions. Hence none of these correlations can be used with enough confidence to estimate (MMP) and applying them is prone to errors. Therefore, the objective of this article is to search for a quick and sturdy mathematical correlation for the mathematical determination of (MMP) based on regression analysis within a shorter period of time. Finally, a comparison between the (MMP) calculated from the proposed correlation and the published ones was presented. Results ensure that the suggested new (MMP) correlation is the more accurate one.     

Monitoring Power Dissipation for Fault Detection

In this paper, we suggest that the dynamic power dissipation of acircuit can be used for fault detection. Even those faults which do notaffect static power dissipation can be detected by monitoring dynamic powerdissipation. We discuss how stuck-at, stuck-open, and redundant faults maybe detected by monitoring dynamic power dissipation. In many cases, theFourier spectra of the supply currents in the good and faulty circuits willalso be very different. Further, specific tests can be applied so as toimprove fault coverage. Power monitoring is verified using simulation, andalso experimentally, for example circuits.     

Behavioral Testability Insertion for Datapath/Controller Circuits

A method for test synthesis in the behavioral domain is described.The approach is based on the notion of adding a test behavior to the normal-mode design behavior. This testbehavior describes the behavior of the design in test mode. Thenormal-mode design behavior and test-mode test behavior are combinedand then synthesized by any general-purpose synthesis system toproduce a testable design with inserted BIST structures. The testbehavior is derived from the design behavior using testabilityanalysis based on metrics that quantify the testability of signalsand variables embedded within behaviors. The insertion method iscombined with a behavioral test scheme thatintegrates a) the design controller and test controller, b) testingof the entire datapath and controller. Examples show that when thetestability insertion procedure is used to modify a behavior beforesynthesis, the resulting synthesized physical implementation isindeed more easily tested than an implementation synthesized directlyfrom the original behavior.     

LYCOS: the Lyngby Co-Synthesis System

This paper describes the LYCOS system, an experimental co-synthesis environment. We present the motivation and philosophy of LYCOS and after an overview of the entire system, the individual parts are described. We use a single CPU, single ASIC target architecture and we describe the techniques we use to estimate metrics concerning hardware, software and communication in this architecture. Finally we present a novel partitioning technique called PACE, which has shown to produce excellent results, and we demonstrate how partitioning is used to do design space exploration.     

图象多通道小波分析的实现

小波变换是近年来兴起的一种时频城信号分析理论，是信号分析处理的一种强有力的新工具．本文根据小波变换的特点，在Mallat多分辨分析的基础上，将小波的“多通道”多分辨分析，推广到了“多通道”多分辨分析、讨论了多通道小波分析的理论和实现方法，并将这一理论应用到了图象处理，实现了图象的多通道小波分析．