基于投影寻踪—正态云模型的地下水水质分级评价

针对现有水质评价方法的缺陷,引入云模型理论建立基于投影寻踪-正态云的水质分级模型。选取总硬度、氟化物、亚硝酸盐、高锰酸盐指数、硫酸盐、氨氮、硝酸盐、氯化物及溶解性总固体等九个指标建立水质评价指标体系,根据既定体系确定评价指标标准及云模型特征参数,以投影寻踪法计算评价指标权重,采用云模型正向发生器计算各指标确定度并生成相应云图,在此基础上得到综合确定度并给出水质评价等级。结合北京市朝阳区19个水质监测井的水质监测样本数据,并通过对比分析验证了该方法的可行性,为水质分级评价提供了新思路。     

基于熵权法赋权的贝叶斯水质评价模型

基于贝叶斯水质评价理论,运用熵权赋权法求各评价指标权重,提出了熵权法赋权的贝叶斯水质评价模型,并以南四湖下级湖徽山站和韩庄闸为例进行了水质评价。结果表明,该模型有效可行,较等权重贝叶斯法对水质所属类别分辨率更高,为水环境保护与治理提供了依据。     

基于改进的AHP-PP模型的重力坝安全综合评价方法

为解决大坝安全综合评价中指标权重完全主观或完全客观的问题,结合层次分析法和投影寻踪法在综合评价中的应用建立了改进的AHP-PP模型,综合评价了济南市卧虎山大坝的安全等级。结果表明,基于层次分析法的主观权重参考了决策者的知识经验,基于投影寻踪的客观权重体现了指标间的内在联系,两者优势互补,加权权重对评价结果更具说服力。综合评价发现该坝处于轻度异常等级,与实际情况相吻合,说明该方法稳定有效。     

约束型ME-PP模型在大坝安全评价中的应用

鉴于大坝安全综合评价中的权重选取关系到评价结果的可靠性、合理性,为充分挖掘大坝监测数据所携带的信息,并考虑影响大坝基岩安全的因素特征,从投影寻踪方法的优化函数和约束条件两个方面改进传统算法,即采用最大熵原理与投影寻踪耦合模型改进投影寻踪方法的优化函数,结合实测指标的特征改进投影寻踪法的约束条件,从而得到约束型最大熵投影寻踪耦合模型。将该模型计算得到的各实测指标权重运用于灰色聚类综合评价,并利用聚类系数向量的灰度进行方法优劣的判别。实例应用结果表明,将本文方法求得的权重用于综合评价是合理可行的,相比于熵权法、传统投影寻踪法,更符合大坝基岩实测数据的特征,且得到的评价结果灰度更小,更易区分所属灰类。     

基于投影寻踪聚类和遗传算法的农村水利现代化水平评价

为科学合理地评价农村水利现代化发展水平,根据农村水利现代化内涵,建立了二层6类共21个指标的评价指标体系,确定了各指标的评价阈值。基于投影寻踪聚类和遗传算法,将评价指标值标准化,再将标准化后的指标值视为投影参数,寻找出最佳的投影方向向量,对照划定好的评价标准,从而确定评价等级,并利用该方法评价了固安县的农村水利现代化发展水平。结果表明,固安县目前处于水利现代化中等水平,与固安县的发展现状基本吻合,表明该方法评价结果比较合理,适用于农村水利现代化评价。     

基于投影寻踪原理的机组可靠性等级评价

以2010年全国火电大机组竞赛运行数据为样本集,根据投影寻踪原理并结合遗传算法优化,建立了超临界600MW火电机组可靠性等级评价模型,并对模型等级评价结果与竞赛结果进行了对比．结果表明：基于投影寻踪原理的机组可靠性等级评价结果与机组竞赛发布结果基本一致．所建模型规避了人为决定权重的缺点,客观性较强、准确有效、应用简便且可操作性强．     

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。     

混沌粒子群优化投影寻踪法在电能质量监测网中的应用

为建设浙江省电能质量监测平台区域电能质量评估模块,根据投影寻踪原理,将电能质量多个单项指标转化为一个综合指标,利用混沌粒子群算法对投影方向进行优化,建立了基于混沌粒子群优化和投影寻踪的电能质量综合评估模型。算例应用结果表明,该模型评估结果更合理、可信度较高。并针对浙江地区的六个变电站的监测网监测数据,给出了相应的评估结果。     

基于投影寻踪主成分分析和耦合模型的风电功率预测

为提高搜索精度和解决样本数据高维性问题,以数值天气预报为基础,提出一种基于投影寻踪和改进状态转移算法优化的风电功率预测模型。该方法首先选取风电场周围多个位置多个高度的气象数值信息,采用投影寻踪主成分分析方法将高维的样本数据投影到低维空间,提取主成分,再建立投影寻踪耦合模型;同时通过加入正交变换的状态转移算法优化最佳投影方向、多项式系数和阈值项,确定网络结构以确保得到最佳模型。以某风电场为实例研究,表明基于投影寻踪和改进状态转移算法的方法可靠性高,能有效解决风电功率预测中存在的预测精度低、数据非线性和高维性等实际难题。     

基于遗传算法的参数投影寻踪回归径流预报模型及应用

为提高径流预报精度,采用单相关系数法挑选预报因子,建立了基于遗传算法的参数投影寻踪回归径流预报模型,利用该模型对雅砻江二滩水电站月平均流量进行了预报。结果表明,与BP神经网络模型预报结果相比,投影寻踪回归模型具有更好的预报结果和更高的预报精度。     

Contents in Volume 23,2014

<正>~~     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

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.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.     

Controls on the Karaha–Telaga Bodas geothermal reservoir,Indonesia

Karaha–Telaga Bodas is a partially vapor-dominated, fracture-controlled geothermal system located adjacent to Galunggung Volcano in western Java, Indonesia. The geothermal system consists of: (1) a caprock, ranging from several hundred to 1600 m in thickness, and characterized by a steep, conductive temperature gradient and low permeability; (2) an underlying vapor-dominated zone that extends below sea level; and (3) a deep liquid-dominated zone with measured temperatures up to 353 °C. Heat is provided by a tabular granodiorite stock encountered at about 3 km depth. A structural analysis of the geothermal system shows that the effective base of the reservoir is controlled either by the boundary between brittle and ductile deformational regimes or by the closure and collapse of fractures within volcanic rocks located above the brittle/ductile transition. The base of the caprock is determined by the distribution of initially low-permeability lithologies above the reservoir; the extent of pervasive clay alteration that has significantly reduced primary rock permeabilities; the distribution of secondary minerals deposited by descending waters; and, locally, by a downward change from a strike-slip to an extensional stress regime. Fluid-producing zones are controlled by both matrix and fracture permeabilities. High matrix permeabilities are associated with lacustrine, pyroclastic, and epiclastic deposits. Productive fractures are those showing the greatest tendency to slip and dilate under the present-day stress conditions. Although the reservoir appears to be in pressure communication across its length, fluid, and gas chemistries vary laterally, suggesting the presence of isolated convection cells.     

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。     

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.