基于突变级数法的山西省水资源脆弱性评价

水资源脆弱性评价是水资源安全研究的重要内容,突变级数法为水资源脆弱性评价方法研究提供了新的视角。通过构建突变级数模型,并利用突变级数原理重新划定分级标准,有效弥补了突变级数法缺陷,对山西省2004～2016年水资源脆弱性从自然脆弱、人为脆弱和承载脆弱三个方面进行评价。结果表明,2004～2016年山西省水资源脆弱度呈波动式变化降低,其中自然脆弱度呈波浪式变化,人为脆弱度呈波动式下降趋势,承载脆弱度呈减少趋势;按照水资源综合脆弱性,山西省可划分为重度脆弱区、中度脆弱区和轻度脆弱区三个区,其中重度脆弱区1个市,中度脆弱区3个市,轻度脆弱区7个市。     

基于混合蛙跳与投影寻踪模型的水资源系统脆弱性评价

研究水资源系统脆弱性有助于水资源可持续利用的实现,结合驱动力—压力—状态—影响—响应(DPSIR)框架构建了水资源系统脆弱性评价指标体系,利用混合蛙跳算法和投影寻踪方法建立了基于混合蛙跳和投影寻踪的水资源系统脆弱性评价模型,以山东省滕州市为研究区,分别从驱动力—压力—状态—影响—响应5个方面及系统整体进行了水资源系统脆弱性评价,并以模型计算的投影值作为衡量系统脆弱程度的依据。结果表明,该区2008年水资源系统指标体系各方面与整体均处于脆弱性中等范围,其中水资源供需矛盾不断加剧及水资源开发利用条件薄弱导致影响、状态两方面脆弱性程度较高,依靠科技进步措施使得响应类指标对脆弱性影响程度较低,与实际情况相符,可见该模型评价结果可行、有效。     

概率论与模糊识别在水资源脆弱性评价中的应用

为准确评价水资源的脆弱性程度,鉴于组合赋权法精度不足等缺点,提出了基于概率论的贝叶斯公式和模糊识别耦合方法,并应用于河南省某市2013年的水资源脆弱性综合评价中。结果表明,某市2013年的水资源脆弱性评价等级为较不脆弱,与实际情况一致。改进后的贝叶斯公式和模糊识别耦合随机评价方法采用了组合赋权法和相对隶属度综合确定权重,从指标间和指标内部两个方面确定指标权重,使评价结果更加趋于合理。研究成果可为水资源管理和开发提供依据。     

湖北省城市内涝灾害脆弱性研究

为研究湖北省城市内涝灾害的脆弱性,基于灾害形成理论,从城市内涝致灾因子、孕灾环境、承灾体、城市抗灾救灾能力四个方面选取14个输入输出指标,建立城市内涝灾害脆弱性评价指标体系,融合数据包络分析模型、交叉评价模型和熵权法,提出湖北省城市内涝灾害脆弱性评价方法,计算湖北省17个市级行政区的内涝脆弱性评价值,区划湖北省各城市内涝脆弱性等级。结果显示,湖北省整体内涝脆弱性水平较高,孝感市和武汉市尤为突出。     

基于复杂网络理论与风险理论的地区电网脆弱性评估

电网脆弱性不仅与电网的网络结构及其电气参数有关,还与电网的实时运行状况及约束条件有关。基于复杂网络理论与风险理论,提出了一种新的电网脆弱性评估方法。首先以节点重要度指标和线路改进介数指标对电网中的脆弱源进行识别;再利用设备状态检修数据建立起脆弱源元件的故障模型,依据设备的健康指数推算出设备的故障可能性,并引入效用理论来评估故障严重度,得到相应的综合静态风险指标;最后基于网络结构特性指标和综合静态风险指标定义了节点脆弱度和线路脆弱度指标,并以某一地区电网为例进行分析,结果表明,文中定义的脆弱度指标能有效地克服以往从单一角度去评估电网脆弱性的弊端,提高了辨识精度与辨识效果,验证了该脆弱性评估方法的合理性及有效性。     

基于熵权法的模糊集对分析模型在乌鲁木齐市水资源脆弱性评价中的应用

针对水资源脆弱性存在的随机性、模糊性和不确定性等特点,根据2011年乌鲁木齐市水资源供需水量,从自然脆弱、人为脆弱和承载脆弱三方面建立了水资源脆弱性评价指标体系,采用熵权法确定指标权重,构建了基于熵权法的模糊集对分析模型,并利用该模型对乌鲁木齐市水资源脆弱性进行评价。结果表明,乌鲁木齐市的8个市辖区县大部分处于中等脆弱级别以上,说明2011年乌鲁木齐市脆弱性级别较高,评价结果与实际情况相符。可见基于熵权法的模糊集对分析模型合理、可靠。     

基于厂站-设备两级电力信息耦合模型的信息设备重要性评估

电力监控系统不仅会受到电力网一次设备的影响,还会面对信息层面网络攻击的威胁,因此评估通信设备的重要性对网络安全及大电网的安全稳定运行尤为重要。针对一般电网的电力监控系统与电力网高度耦合的特点,建立了基于厂站-设备两级的信息网与电力网耦合模型：第一级是由发电厂、变电站、调度中心组合而成的厂站级相依网络,第二级是由通信设备与电力设备组合而成的设备级复杂网络;构建了两级耦合网络的通信节点重要度指标和信息网络脆弱性指标;以山东省济南市某小型电网的电力监控系统为例,计算其网络指标,验证了该方法的有效性。该文对信息网络的风险评估具有指导意义。     

基于集对分析模型的巢湖流域水资源系统脆弱性评价

鉴于水资源系统脆弱性是一个复杂的系统工程,从水资源脆弱性、生态环境脆弱性和承载能力脆弱性三方面构建了流域水资源系统脆弱性指标体系,利用同异反层次法联系数建立了流域水资源系统脆弱性评价的集对分析模型,并对巢湖流域水资源系统脆弱性进行了综合评价。结果表明,巢湖流域水资源系统脆弱性为中度脆弱,各区域承载能力脆弱性均较高,但水资源脆弱性和生态环境脆弱性也不容忽视,应加强流域水资源综合治理,提高综合治理成效。     

地区性河湖水系连通脆弱性评价方法及应用

在对河湖水系连通脆弱性分类基础上,指出河湖水系连通脆弱性扰动可分为本质脆弱性扰动、特殊脆弱性扰动,进而探讨了河湖水系连通脆弱性、敏感性和适应性三者之间的关系,构建了河湖水系连通脆弱性的敏感性指标体系,分析了河湖水系连通的适应性,提出了河湖水系连通脆弱性评价方法,并据此评价了辽宁省中部六城市地区的河湖水系连通脆弱性,指出该六城市群已处于河湖水系连通极脆弱区,亟需实施大伙房水库输水工程调水。     

基于熵权的玉溪市水资源脆弱性及其时空异质性研究

研究水资源脆弱性对玉溪市水资源安全保障、洪旱灾害应对具有重要意义。以玉溪市县级行政区为例,基于熵权法构建了水资源脆弱性评价模型,研究了玉溪市2005~2015年水资源脆弱性及其时空异质性。结果表明,玉溪市水资源脆弱性存在显著时空异质性,空间上呈现东高西低的格局,随着时间演进脆弱性普遍增强。红塔区属于强脆弱地区,澄江县、江川区、通海县属于中脆弱地区;其余西部各县为弱脆弱地区。2005~2015年玉溪市水资源脆弱性变化趋势大体为先增加后小幅减小,2009年因降水量剧减、供需矛盾加剧导致其脆弱性最强,2005~2008年脆弱性较为接近,其中2007年最小。水资源脆弱性强的地区往往处于经济发展迅速、水资源需求量大或干旱频发的地区。     

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

<正>~~     

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.     

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。     

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.