基于灰靶理论的城市应急供水方案评价研究

针对城市应急供水方案选择面临的多目标评价问题,从水量、水质、工程难度、工程投资等方面建立城市应急供水方案评价指标体系,运用灰靶理论,通过建立标准模式、灰靶变换、构建灰关联差异信息空间、计算灰关联系数和靶心系数,逐层次识别模式接近靶心度的程度,从而对方案进行评价及排序,最终选定方案6作为德阳市应急供水方案,为德阳市灾后重建城市供水提供了重要的科学依据.该方法适合处理信息不完全、少数据不确定性问题更简洁、高效、可行.     

C0-半群的概率型逼近

借助于算子值数学期望以及概率论方法,利用适当的随机变量的矩生成函数估计式,讨论了Banach空间上C0-半群的概率表示式及收敛速度的估计式.     

Hydroformylation of functional alkenes with heterodonor phosphine rhodium catalysts: substrate or ligand directed regioselectivity?

The catalytic activity and selectivity of heterodonor phosphine rhodium catalysts prepared in situ were tested in the hydroformylation of functional alkenes (ethyl acrylate, methyl methacrylate, styrene, 4-vinyl-1-cyclohexene, dicyclopentadiene and cis-1,2,3,6-tetrahydrophthalic anhydride). Systematic variation of the heterodonor atom in the ortho position of the ligand showed that the heterodonor atom has a significant influence on the activities and selectivities of the reaction. However, the activity seems to depend mainly on the modifying ligand, and the regioselectivity mainly on the substrate (i.e., the structure and functionality of the alkene). Nevertheless, regioselective control is only obtained through synergy between the substrate and the catalyst. Clear regiocontrol was observed in the hydroformylation of ,-unsaturated esters and styrene with an in situ formed o-(thiomethylphenyl)diphenylphosphine rhodium catalyst.     

Disruption of Secondary Attraction of the Spruce Beetle, Dendroctonus rufipennis, by Pheromones of Two Sympatric Species

Capture of spruce beetles, Dendroctonus rufipennis, in multiple-funnel traps baited with frontalin and -pinene was reduced by up to 42% in the presence of synthetic (+)-exo- and (+)-endo-brevicomin, aggregation pheromones of the sympatric species Dryocoeles affaber. (±)-endo-Brevicomin was inhibitory to spruce beetles in two experiments and (±)-exo-brevicomin was inhibitory in one experiment, reducing spruce beetle trap catches by up to 87% and 75%, respectively. Spruce beetle trap catches were also reduced by 85% by (±)- or (+)-ipsdienol, but not by (–)-ipsdienol. Ips tridens, a second sympatric species, produces both enantiomers of ipsdienol in its pheromone blend. Responses by D. affaber to its own pheromone were significantly enhanced by addition of the spruce beetle lure. Enantiospecific pheromones of secondary competing species, or less costly racemic substitutes, may be useful for managing spruce beetles using competitive displacement or exclusion. Baiting susceptible hosts with pheromones of secondary species may enhance attack by secondary species, while partially repelling spruce beetles.     

The kinetics of hydrogen transport through amorphous Pd82−yNiySi18 alloys (y=0-32) by analysis of anodic current transient

Hydrogen transport through amorphous Pd_82−yNi_ySi₁₈ alloys (y=0-32) was investigated in 0.1 M NaOH solution by analysis of the anodic current transient. It was found that the anodic current transient shows the non-Cottrell behaviour, but its shape and value remain nearly constant regardless of the hydrogen discharging potential. From the coincidence of the anodic current transient theoretically calculated with that experimentally measured, it is suggested that the change in surface concentration of hydrogen with time is uniquely given by the rate of hydrogen transfer from absorbed state at the electrode sub-surface to adsorbed state on the electrode surface. This means that neither the ‘constraint of constant concentration’ nor the ‘constraint by Butler-Volmer behaviour’ is effective at the electrode surface during hydrogen extraction. On the basis of the theoretical current-time relation under the ‘constraint by hydrogen transfer of absorbed state to adsorbed state’, the hydrogen diffusivity was determined to have an almost constant value of (1.3±0.4)×10⁻⁸ cm² s⁻¹, irrespective of the Ni content and in the absence of Ni. On the other hand, it is inferred that the rate constant of hydrogen transfer decreases markedly with increasing Ni content due to the Ni(OH)₂ layer formed on the electrode surface.     

Etude de l'oxydation du pentachlorophénol dans différentes géométries de réacteurs à ultrasons de haute fréquence

The determination of the key geometric parameters used for high-frequency sonoreactor modeling has been studied. The methodology allowing the characterization of the different reactors built in our laboratory has been defined. The methods are: calorimetry, determination of the residence time distributions, the observation of the chemiluminescence of luminol and the degradations of a prototype molecule: pentachlorophenol. After characterization of the studied reactors, it seems that volumetric power, with equivalent emitting system, is the major parameter of the reactor's performance.     

Activation of Ni/A12O3 catalysts through modification of the Al2O3 support

The effect of alumina pretreatment on the performance of alumina supported nickel catalysts was demonstrated in gas phase hydrogenation of toluene to methylcyclohexane. The state of the alumina was changed from pure to pure phase through various heat treatments in air. The catalysts were prepared from vapor phase by saturating the accessible binding sites on the pretreated alumina with the nickel precursor. The highest number of active sites for hydrogenation was observed for catalysts prepared on alumina having an incomplete phase transition and a / alumina phase ratio between 0.5 and 10. Results from temperature programmed desorption (TPD) studies revealed that a maximum in weakly chemisorbed hydrogen as well as in total amount of desorbed hydrogen was found for the same catalysts. By hydrogen chemisorption studies the total hydrogen uptake was found to correlate with the observed hydrogenation maximum. It is suggested that both the chemical and physical properties of the alumina influence the activity. An optimal metal-support interaction and structural defects on the alumina due to the phase transition can explain the observed maximum in the number of active sites and in hydrogen uptake.     

Catalytic Combustion of Model Carbon Particles (CPs) over Pt/β-SiC Catalyst

Platinum catalyst supported on a medium surface area -SiC was successfully used for the catalytic combustion of model carbon particles and compared to a catalyst supported on a low surface area -SiC. The -SiC-based catalyst showed no deactivation as a function of cycling tests while a strong deactivation was observed on the -SiC-based catalyst. This deactivation was attributed to the progressive encapsulation of the platinum particles by a layer of silica which built up during the combustion cycle. These results render possible the use of Pt/-SiC catalyst as a diesel carbon particle catalytic filter with continuous regeneration.     

New sesquiterpenes fromMaytenus species (Celastraceae). Taxonomic and chemotaxonomic considerations concerning chileanMaytenus

Three new dihydro--agarofuran sesquiterpenes from two species ofMaytenus were isolated and their structures were elucidated by means of¹H and¹³C NMR studies. The differences and similarities noted in the chemical content of the dihydro--agarofuran sesquiterpenes from the fourMaytenus species from Chile are in line with the taxonomic characterization of these species; their geographical distribution is also given.     

β-Phellandrene: kairomone for pine engraver,Ips pini (Say) (Coleoptera: Scolytidae)

The responses ofIps pini (Scolytidae) to multiple-funnel traps baited with the pheromone, ipsdienol, and various monoterpenes were determined in stands of lodgepole pine in southern and central British Columbia.Ips pini was attracted to both ipsdienol and -phellandrene, demonstrating that -phellandrene is a kairomone for this species.Lasconotus complex (Colydiidae) and aCorticeus sp. (Tenebrionidae) were attracted to both ipsdienol and -phellandrene. TheCorticeus sp. exhibited a synergistic response to the combination of ipsdienol and -phellandrene; the responses of the other two species to the combination were additive. The predators,Thanasimus undatulus, Enoclerus sphegeus, andE. lecontei (Cleridae), were attracted to ipsdienol-baited traps, whileMonochamus clamator (Cerambycidae) andDendroctonus ponderosae (Scolytidae) were attracted to -phellandrene. Attraction of all eight species increased with increasing release rates of ipsdienol and/or -phellandrene.