CSI全自动机器故障专家诊断系统

机器故障诊断专家系统在生产现场的应用,既能提高故障诊断的准确率,又能节省大量的人力和时间,对专家系统的研制也是当前设备诊断技术发展的一个方向;美国CSI工业系统有限公司基于许多机械振动专家几十年来机器故障诊断的经验,经过对全世界几千用户无数次现场验证和不断扩充知识库,最近推出了人工智能型全自动机器故障专家诊断系统,能     

CSI全自动机器故障专家诊断系统及其应用

ＣＳＩ全自动机器故障专家诊断系统及其应用美国ＣＳＩ工业系统有限公司基于许多机械振动专家几十年来机器故障诊断的经验，经过对全世界几千用户无数次现场验证和不断扩充知识库，最近推出了人工智能型全自动机器故障专家诊断系统，能对旋转机械多达６７类的机械故障进行...     

太阳能及空气源热泵复合供热系统故障诊断研究与应用

为确保复杂太阳能热水系统的稳定运行,有必要采集实时运行数据从中获取故障特征信号,通过专家系统进行自动故障诊断。采用故障树分析方法,以太阳能热利用系统典型故障为例构建故障树,求解最小割集,并以此为基础建立诊断知识库;运用正向推理结合人工辅助决策机制进行故障诊断和定位,建立故障诊断专家系统。开发故障诊断软件,并在工程中进行测试,验证故障辨识的准确性。     

基于图像识别技术的旋转机械振动故障诊断方法

目前振动信号的分析主要是针对特定测点在某一瞬间采集的一段振动波形,提取其中的特征量来进行故障诊断,这种基于状态信息的诊断方法对故障类型的辨别能力有限。通过构造基于归一化幅值谱的三维矩阵来刻画旋转机械振动故障的过程变化规律,并引入图像识别技术,在此基础上建立了一种基于归一化幅值谱图识别的旋转机械振动故障诊断方法。并通过该方法对试验台获取的振动故障信号进行分析,计算结果表明该方法是一种有效的故障诊断方法。     

旋转机械振动故障的模糊诊断

在分析了旋转机械振动故障诊断存在的困难之后,建立了故障机理研究和故障诊断的数学模型。根据征兆对故障的肯定和否定程度,提出了故障诊断的模糊筛选矩阵,实现了对复杂故障的诊断。     

调速器故障诊断

针对调速器故障征兆和原因的复杂性,根据水电站调速器故障事实,结合专家的实际经验构建调速系统故障诊断知识库,建立故障诊断专家系统.实例表明,该系统推理准确性高,满足调速器故障诊断的实用性要求.     

模糊专家系统及其在汽轮发电机组故障诊断中的应用

提出了一种用于汽轮发电机组故障诊断的模糊专家系统,分析了人机界面、解释机、知识库及推理机四部分功能;通过研究诊断规则的前提条件、权系数、前提真度及模糊结论置信度的确定方法,实现了知识库中模糊产生式规则表达;研究了基于正向推理控制策略的模糊推理方法,并分析了诊断结果的冲突消解方法。通过对汽轮发电机组汽流激振故障的案例分析,验证了本文模糊专家系统的有效性,为汽轮发电机组故障诊断提供了一种有效可行的方法。     

基于模糊专家系统的汽轮机远程振动故障诊断系统的设计与开发

详细介绍了一套基于模糊专家系统的汽轮机振动故障诊断系统的设计与开发细节。系统采用分布式架构,由数据采集与分析子系统、振动数据与特征数据存储子系统、智能监测与诊断子系统和人机交互子系统等四大子系统组成。智能监测与诊断子系统采用了知识库/推理机结构,推理机基于自主开发的基于模糊Rete算法的模糊专家系统,支持海量规则和特征的匹配。通过对仿真的故障进行诊断,验证了整套系统的有效性。     

一种实时在线诊断旋转机械振动故障的方法

为实现旋转机械振动故障实时在线诊断,采集机组运行中的振动信号,计算得到不同振动故障时的特征值及其敏感等级分布,确认了特征值与不同故障原因的相关性,建立了故障特征值数据库,并在旋转机械试验台上对故障诊断模型进行了验证.结果表明:该方法可以实时有效地完成振动故障的在线分析和不同故障原因的诊断,对风机和水泵等旋转机械的现场实时监测和振动智能远程诊断具有一定的工程应用价值.     

柴油机模糊诊断专家系统的研究

介绍了一种以关系数据库为基础的机车柴油机多征兆模糊故障诊断专家系统,研究了多征兆模糊产生式规则的诊断知识表示和知识库的建立;利用ADO技术实现对知识库的访问和诊断管理。在柴油机故障诊断应用中,该数据库取得了良好的效果。     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

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Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.