重庆都市区居民食品水足迹消耗供需平衡研究

研究食品水足迹消耗对区域水资源持续利用具有重要意义。基于虚拟水和水足迹理论,核算了2001～2011年重庆都市区食品水足迹供给量、食品水足迹消耗量和食品水足迹贸易量,并分析三者变化的原因。研究结果表明,食品水足迹供给量由2001年的20.05×108m3下降到2011年的17.43×108m3,食品水足迹消耗量由2001年的35.43×108m3增长到2011年的46.57×108m3;食品水足迹供给量小于消耗量,食品水足迹进口量由2001年的18.343×108m3增长到2011年的30.882×108m3。生产规模缩小是食品水足迹供给量下降的原因,人口增长和生活水平提高导致食品水足迹消耗量增长。在进口食品水足迹的同时需改进生产方式和调整食品消耗模式,以缓解食品水足迹供需矛盾。     

东阿县沿黄区孔隙地下水化学特征及成因分析

基于东阿县牛角店镇、乐平铺镇等地区38组孔隙水样品和3组黄河水样品,采用水化学离子比法和氢氧同位素分析法,系统分析了东阿县沿黄区孔隙水化学特征的形成机理及黄河水对孔隙水的影响。结果表明,研究区孔隙地下水以HCO₃-Na型为主,含水层中主要发生硅酸盐岩溶解和碳酸岩溶解过程;黄河水入渗、大气降水的入渗和水-岩相互作用是区内地下水化学成因的主导因素;区内地下水化学与同位素特征反映出研究区内黄河影响带范围在18 km以内,影响带范围内地下水参与外界循环不积极,主要受黄河水的补给,地下水化学组成主要受黄河水和水-岩相互作用的影响,在影响带范围外地下水化学组成受到大气降水的影响程度增大。     

桐梓隧道岩溶地下水化学特征及水质评价

为分析桐梓隧道岩溶地下水水化学特征和水质情况,运用Piper三线图、Gibbs模型、离子比例系数及Pearson相关系数矩阵等方法探究其类型及成因,并结合模糊综合评价法对地下水水质进行分类评价。结果表明,研究区地下水中Mg~(2+)、Ca~(2+)、HCO_3~-占主要优势,Mn、As、Se的含量极低;地下水化学类型以HCO_3-Ca、HCO_3·SO_4-Ca·Mg型水为主;水化学形成主要来源于岩石风化碳酸盐岩(如方解石、白云石),少部分来源于硅酸盐岩、石膏、钠长石等矿物溶滤,大气降水和人为因素也有一定影响,表现为隧道施工加速了岩石溶蚀风化;模糊综合评价表明研究区地下水水质良好,以Ⅰ、Ⅲ类为主。研究结果可为隧道区地下水水资源保护及利用提供参考。     

泰莱盆地地下水水化学特征及水质评价

为分析泰莱盆地地下水水化学特征及水质现状,选取2017年丰水期140件水样,其中,孔隙水样47件、岩溶水样61件和裂隙水样32件,运用数理统计、Piper三线图、箱型图等方法,分析了研究区主要离子及水化学特征,并运用模糊综合评价法、Wilcox图解法评价了水质现状及灌溉水质。结果表明,泰莱盆地主要阳离子为Ca~(2+)、Na~+,占阳离子总数的80%以上,主要阴离子为HCO_3~-、SO_4~(2-),占阴离子总数的67%以上,其中NO3-含量也相对较高;水化学类型以HCO3·SO4-Ca型水为主;pH值整体呈弱碱性,TDS存在孔隙水岩溶水裂隙水的关系,这与地下水径流条件有关;Ⅳ、Ⅴ类水样占总水样的29.3%,影响因子为SO_4~(2-)、NO3-、TDS、总硬度,其主要影响因素为人为活动;绝大部分区域均属于好—可用及以上级别,合理利用地下水灌溉可有效预防土壤盐碱化问题。     

豫北平原地下水水化学和水质分布特征

豫北平原为河南省重要的农业生产基地,其居民生活用水和农业生产用水主要依赖于地下水。为了保证工农业生产和生活用水安全,根据2018年的105个地下水化学取样分析数据,利用Piper三线图和Gibbs图研究了水化学的主要离子的空间分布特征及水化学形成机制,从而揭示了研究区水化学分布特征和主要形成作用,采用综合指标法和单因子法评价了水质问题,并分析了主要影响因素的超标情况。结果表明,豫北平原地下水类型以HCO3 Ca·Mg、HCO3·SO4 Mg·Na、HCO3·Cl Na型水为主,地下水水化学成因以蒸发浓缩和水岩相互作用为主,浅层、中深层地下水水质Ⅳ~Ⅴ类水分布面积约占90%,深层地下水水质较好,Ⅱ~Ⅲ类水分布面积约占40%。     

抚松县天然矿泉水水化学特征及形成机理

为分析抚松县天然矿泉水水化学特征及形成机理,2017年采集天然矿泉水样品20组,综合运用Piper三线图、水化学类型分区图,分析抚松县天然矿泉水水化学特征;运用离子比值分析法、反向地球化学模拟分析矿泉水的形成机理。结果表明,抚松县天然矿泉水pH值为7.9~8.4,属弱碱性矿泉水,偏硅酸含量为33~53mg/L,属偏硅酸型矿泉水;天然矿泉水中Ca^2+、HCO3^-为优势离子;水化学类型主要有HCO3^-Ca型、HCO3^-Ca·Na型和HCO3^-Ca·Mg型。离子比值分析法和PHREEQC结果表明,该区水中主要离子受长石类、橄榄石、辉石的溶解-沉淀作用和阳离子交替吸附作用控制。     

阳泉市娘子关岩溶地下水水化学特征及其成因

针对娘子关泉域水化学分析不能即时评价且偏主观性的问题,加入离子空间分布图,对娘子关泉域岩溶地下水的13个水化学特征指标运用描述性统计、水化学类型、TDS和总硬度分布图等进行分析,并辅助以Pearson相关分析探究其成因。结果表明,个别水样超过地下水环境质量标准,Fe~(3+)、Na~+具有较大空间变化,其他元素相对稳定;除少部分为微咸水和软水、微硬水、硬水,大部分地区为淡水和极硬水;地下水水化学类型以HCO_3-Ca·Mg、SO_4·HCO_3-Ca、SO_4·HCO_3-Ca·Mg型为主,部分补给区和径流区已转变为硫酸盐类型为主的水。该水化学特征成因主要受工矿产业影响,其次受水岩作用和农业、生活污染的影响。     

井陉地区岩溶地下水水化学特征及其影响因素分析

基于2018年9月采集的24件丰水期地下水样品分析测试结果,综合运用数理统计、Piper三线图、相关性分析、Gibbs图和主要离子比值法等分析井陉地区岩溶地下水水化学特征及其影响因素。结果表明,岩溶地下水的主要阴阳离子为HCO3-、SO24-、Ca2+,水化学类型主要为SO4·HCO3-Ca、HCO3·SO4-Ca型;局部地区出现地下水点状污染,超标水点分布在工矿企业和农田等地区,主要影响指标为总硬度、硫酸盐和硝酸盐;地下水水化学主要受水岩作用控制,但也受人为因素、地下水径流方向及地表水影响。其中水岩作用主要以碳酸盐岩、硫酸盐岩和岩盐矿物风化溶解为主,也存在不同程度的阳离子交换作用;人为因素主要以工矿业污染为主。研究结果为井陉地区岩溶地下水污染防治提供了理论参考。     

锦州市小凌河扇地地表水与地下水水化学特征

为研究小凌河扇地的水化学特征与地表水—地下水的转化关系,在野外调查和取样的基础上,通过水化学和同位素方法,分析了小凌河扇地自山前至近海平原地表水与地下水的水化学及同位素特征、补给来源及局部差异.结果 表明,从山前地区至近海平原区,区内地下水低矿化度的HCOs-Ca型淡水逐步转变为Cl-Na型微咸水,地表水由HCO3·S...     

白城市潜水水化学特征及成因分析

为研究白城市潜水水化学特征及成因,根据研究区水文地质条件将研究区划分为两个子区域,分别为补给区洮儿河扇形地和径流区扇形地以外平原区,采用相关性分析、Piper三线图、Gibbs图、离子比例系数及反向地球化学模拟等方法分析了研究区的两个子区域潜水水化学成因及影响因素。结果表明,补给区以HCO_3-Ca·Na型水为主,在径流区随水流方向逐渐向HCO_3-Na型水进行转化,且在这一过程中TDS也逐渐增大;岩盐、硅酸盐、碳酸盐和硫酸盐的风化溶解是潜水中离子的主要来源;潜水水化学成分主要受岩石风化作用控制,同时还受到阳离子交替吸附作用、蒸发浓缩作用及人类活动的影响。     

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.