基于粒子群优化的锅炉汽包水位模糊PID控制

结合粒子群优化算法、模糊控制和PID参数自整定方法,设计一种新型自适应模糊PID控制器。采用粒子群优化算法离线优化PID控制器参数,再利用模糊控制器在线对PID参数进行整定。Simulink-~件模型仿真对比表明：控制方法具有调节精度高、     

利用Matlab/Fuzzy Logic进行柴油机电子调速器PID参数模糊自整定设计与仿真

电站柴油机电子调速器PID参数模糊自整定是目前研究的一个方向，模糊控制系统的设计是模糊控制应用中的主要工作，而系统的仿真是设计中的重要步骤和必要的保证。本文介绍了如何利用Matlab中Fuzzy Logic工具箱及Simulink仿真平台进行电站柴油机电子调速器PID参数模糊自整定的设计与仿真。这种方法使模糊控制的设计、仿真及优化变得容易、直观且迅速。     

利用模糊理论改善电子调速器控制性能

柴油机电子调速器一般采用PID（比例、积分、微分）算法控制,为了提高系统的调速性能,在系统过渡过程的不同阶段控制器应取不同的增益,即应实时校正PID的参数。在实际系统中,校正的方法可通过分析被控量的测量值,然后查询校正表进行。但要获得一个精细合适的校正表,须通过大量实验,工作量很大,调整也很不方便。本文利用Fuzzy（模糊）理论对电子调速器PID控制的参数进行实时校准,使电子调速器的控制性能得到改善。     

车用柴油机电子调速器的模糊控制研究

应用模糊控制方法对车用柴油机电子调速器的油门执行器位置伺服控制进行研究。模糊控制方法的显著特点是不需要对控制目标建立精确的数学模型。在常规的模糊控制器上提出一种在线修正因子和量化因子的自调整模糊控制器。这种修正算法是基于仿人工智能控制的思想,分析和识别系统的输出状态,动态地、独立地对量化因子和比例因子进行在线修正,以调整整个控制过程不同阶段的控制特性。发动机的台架试验结果证明油门执行机构获得了良好的动态响应特性。     

模糊PID数字调速器的设计

采用模糊控制原理,进行了模糊ＰＩＤ数字调速器的硬软件设计,实现了ＰＩＤ控制参数在线实时调节。该调速器在ＢＦ４１３Ｌ８Ｆ柴油机上进行了调速特性实验,实验结果表明系统的调速性能得到进一步提高。     

基于参数模糊自整定的PID控制器

为满足在不同偏差e和偏差变化率ec对PID参数自整定的要求,利用模糊控制规则在线对PID参数进行修改,构成了参数模糊自整定PID控制器.……     

基于Viking35的电液调速器PID设定对柴油机调速特性影响的研究

基于Viking35控制器和执行器组成的电液调速器在实船柴油机转速控制上的应用,详细介绍了该控制器的PID参数设定方法,并通过实船柴油机不同PID参数调速特性控制的测试结果,总结出柴油机转速响应特性及控制效果均理想的最优PID参数设定。     

柴油机电子调速器PID参数模糊自校正研究

提出了对柴油机数字式电子调速器PID参数按调速系统过渡过程进行模糊自校正的原理,并对此进行了仿真研究。结果表明,该方法对提高电子调速器的调速性能有明显效果,对电子调速器适应柴油机过程参数的变化也有一定的改善。     

柴油机模糊-PID控制器的设计与验证

针对实际应用中的PID控制策略,存在着自身的稳定性和快速性矛盾,以及柴油机的非线性、时变、时延等特点。本文基于PID控制和模糊控制理论,结合专家丰富经验,通过变量模糊化、模糊推理、模糊规则制定、解模糊判决等,设计了一种新型的模糊自校正PID控制器。试验结果显示．设计的模糊自校正PID控制器对柴油机在不同运行条件下的工况,有着很好的适应性,能够很好地满足柴油机运行指标的要求。     

基于修正因子模糊数模型的柴油机调速技术研究

介绍了基于修正因子模糊数模型的模糊控制算法在柴油机调速技术上的应用。仿真结果和试验结果表明，使用该算法的控制器有很好的调速性能，并对柴油机参数变化具有较强的适应性。     

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%.     

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.     

Contents in Volume 23,2014

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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.