水资源管理研究进展

加强水资源管理是世界各国为提高水资源利用效率和应对水资源危机的重要举措之一,也是我国解决日益增长的水资源需求和水资源供给不足矛盾的关键。 水资源管理研究的领域较广、范围较大、主题较多,主要从国内外水资源管理的模式与制度、研究模型、研究重点领域以及研究热点四方面进行归纳综述,并以黑河流域为例,说明先进的水资源管理对提高水资源利用效率和应对水资源危机的重要性,可为我国探索水资源管理模式,建立适合国情的水资源管理制度提供科学基础。     

基于资源随机中断的反应性多模式项目调度优化

资源中断是项目实施过程中一种常见现象,它会导致项目进度计划的变更并引起额外的成本。本文研究资源随机中断下的项目调度问题,目标是对基准进度计划进行合理的调整,以最小化由此所造成的额外成本。作者首先对研究问题进行界定,随后构建问题的优化模型。针对模型的NP-hard属性,设计禁忌搜索启发式算法。最后以基准列表算法和随机生成算法为参照,在随机生成的标准算例集合上对算法进行测试,得到如下结论:在可接受的计算时间范围内,禁忌搜索获得的满意解质量明显高于其他两种启发式算法;算法的平均计算时间随着项目活动数的增加而增加,随着网络复杂度、资源强度或资源中断次数的增加而减小;满意解的平均目标函数值,随着项目活动数或网络复杂度的增加而增加,随着资源中断次数的增加而减小,与资源强度无明显关系。     

基于电能节约的E-DEA模型及其应用

按照全要素能源效率的概念,重点考虑电能投入约束,构造了基于电能节约的E-DEA模型,其目标函数为极大化产出比例和电能投入比例之差,约束条件中除考虑一般投入量约束外,还同时强调电能投入径向节约和产出径向增加。根据模型最优解,给出了相应的有效、非有效、弱有效、用电规模收益状态的判断准则,以及相应于不同有效性情况下决策单元的改进。以合肥市通用制造业规上企业所属21个行业为研究对象,从第二次经济普查中选择年均资产、从业人员、电力、非电力能源、二氧化碳排量为投入指标,主营业务收入为产出指标,对行业电能利用效率进行实证分析,通过分析潜在电能可节约量和主营业务收入可增加量,明确了各行业改进目标。     

The Kolkata Paise Restaurant problem and resource utilization

We study the dynamics of the “Kolkata Paise Restaurant problem”. The problem is the following: In each period, N agents have to choose between N restaurants. Agents have a common ranking of the restaurants. Restaurants can only serve one customer. When more than one customer arrives at the same restaurant, one customer is chosen at random and is served; the others do not get the service. We first introduce the one-shot versions of the Kolkata Paise Restaurant problem which we call one-shot KPR games. We then study the dynamics of the Kolkata Paise Restaurant problem (which is a repeated game version of any given one shot KPR game) for large N. For statistical analysis, we explore the long time steady state behavior. In many such models with myopic agents we get under-utilization of resources, that is, we get a lower aggregate payoff compared to the social optimum. We study a number of myopic strategies, focusing on the average occupation fraction of restaurants.     

傅里叶变换近红外光谱信息资源共享的基础研究

为了实现农产品傅里叶变换近红外光谱库信息资源的共享 ,使光谱库的信息资源达到充分利用 ,首先研究了仪器间光谱信息的准确表达 ,即仪器到仪器光谱信息间的映射 ;并以映射光谱研究了用于不同仪器上进行定量分析的无标样建模方法。对于 2 2个小麦样品蛋白质含量 ,无标样建模模型预测值与凯氏定氮结果的相关系数r =0 94 1,平均相对误差为 3 2 8% ;为了考察无标样建模模型定量分析的使用性 ,同时亦对 2 2个小麦样品的蛋白质含量采用有标样建模定量分析 ,模型预测值与凯氏定氮结果的相关系数r =0 96 3,平均相对误差为 2 4 %。有标样建模与无标样建模的模型分析结果的比较 ,为不同仪器间光谱信息的可共享性提供了依据。由此根据不同仪器建立的光谱信息库的库信息即可转化为另一仪器的映射光谱信息 ,保证了光谱库信息资源在不同仪器上的共享利用     

二元光学透镜在资源卫星中的应用

使用一种基于二元光学透镜的分光成像及消色差原理的新方法来设计资源卫星的中继光学系统。通过分析二元光学透镜的分光成像原理、消色差原理、衍射效率与阶数和工作波长及设计波长的比之间的关系,又考虑到单独设计制造二元光学透镜的难度,采用折衍混合成像光学系统来拟定资源卫星中继光学系统的设计方案,给出用ZEMAX软件设计的具体结果。设计实例及分析结果表明,包含二元光学透镜的折衍混合成像系统可以很好的实现光谱波段分离,用于资源卫星的光学系统具有一定的适用性。     

Utilization of α-olefins obtained by pyrolysis of waste high density polyethylene to synthesize α-olefin-succinic-anhydride based cold flow improvers

A new route of utilization of α-olefin rich hydrocarbon fractions obtained by waste polymer pyrolysis was investigated. α-olefin-succinic-anhydride intermediate-based pour point depressant additives for diesel fuel were synthesized, in which reactions needed α-olefins were obtained by pyrolysis of waste high-density polyethylene (HDPE). Fraction of α-olefins was produced by the de-polymerization of plastic waste in a tube reactor at 500℃ in the absence of catalysts and air. C_17~22 range of mixtures of olefins and paraffins were separated for synthesis and then, these hydrocarbons were reacted with maleic-anhydride (MA) for formation of α-olefin-succinic-anhydride intermediates. The olefin-rich hydrocarbon fraction contained approximately 60% of olefins, including 90%~95% α-olefins. Other intermediates were produced in the same way by using commercial C₂₀ α-olefin instead of C_17~22 olefin mixture. The two different experimental intermediates with number average molecular weights of 1850g/mol and 1760g/mol were reacted with different alcohols: 1-butanol, 1-hexanol, 1-octanol, i-butanol, and c-hexanol to produce their ester derivatives. The synthesized ten experimental pour point depressants were added in different concentrations to conventional diesel fuel, which had no other additive content before. The structure and efficiency of experimental additives were followed by different standardized and non-standardized methods. Results showed that the experimental additives on the basis of the product of waste pyrolysis were able to decrease not only the pour but also the cloud point and cold filter plugging point (CFPP) of diesel fuel, whose effects could be observed even if the concentration of additives was low. Furthermore, all additives had anti-wear and anti-friction effects in diesel fuel.     

Biomass Productivities in Wild Type and Pigment Mutant of <Emphasis Type="Italic">Cyclotella</Emphasis> sp. (Diatom)

Microalgae are expected to play a significant role in greenhouse gas mitigation because they can utilize CO₂ from power plant flue gases directly while producing a variety of renewable carbon-neutral biofuels. In order for such a microalgal climate change mitigation strategy to become economically feasible, it will be necessary to significantly improve biomass productivities. One approach to achieve this objective is to reduce, via mutagenesis, the number of light-harvesting pigments, which, according to theory, should significantly improve the light utilization efficiency, primarily by increasing the light intensity at which photosynthesis saturates (I _s). Employing chemical (ethylmethylsulfonate) and UV mutagenesis of a wild-type strain of the diatom Cyclotella, approximately 10,000 pigment mutants were generated, and two of the most promising ones (CM1 and CM1-1) were subjected to further testing in both laboratory cultures and outdoor ponds. Measurements of photosynthetic oxygen production rates as a function of light intensity (i.e., P–I curves) of samples taken from laboratory batch cultures during the exponential and linear growth phase indicated that the light intensity at which photosynthesis saturates (I _s) was two to three times greater in the pigment mutant CM1-1 than in the wild type, i.e., 355–443 versus 116–169 μmol/m² s, respectively. While theory, i.e., the Bush equation, predicts that such a significant gain in I _s should increase light utilization efficiencies and thus biomass productivities, particularly at high light intensities, no improvements in biomass productivities were observed in either semi-continuous laboratory cultures or outdoor ponds. In fact, the maximum biomass productivity in semi-continuous laboratory culture was always greater in the wild type than in the mutant, namely 883 versus 725 mg/L day, respectively, at low light intensity (200 μmol/m² s) and 1,229 versus 1,043 mg/L day, respectively, at high light intensity (1,000 μmol/m² s). Similarly, the biomass productivities measured in outdoor ponds were significantly lower for the mutant than for the wild type. Given that these mutants have not been completely characterized in these initial studies, the exact reasons for their poor performance are not known. Most likely, it is possible that the mutation procedure affected other photosynthetic or metabolic processes. This hypothesis was partially validated by the observation that the pigment mutant had a longer lag period following inoculation, a lower maximum specific growth rate, and poorer stability than the wild type.     

Utilization and transport of l-arabinose by non-Saccharomyces yeasts

l-Arabinose is one of the sugars found in hemicellulose, a major component of plant cell walls. The ability to convert l-arabinose to ethanol would improve the economics of biomass to ethanol fermentations. One of the limitations for l-arabinose fermentation in the current engineered Saccharomyces cerevisiae strains is poor transport of the sugar. To better understand l-arabinose transport and use in yeasts and to identify a source for efficient l-arabinose transporters, 165 non-Saccharomyces yeast strains were studied. These yeast strains were arranged into six groups based on the minimum time required to utilize 20 g/L of l-arabinose. Initial transport rates of l-arabinose were determined for several species and a more comprehensive transport study was done in four selected species. Detailed transport kinetics in Arxula adeninivorans suggested both low and high affinity components while Debaryomyces hansenii var. fabryii, Kluyveromyces marxianus and Pichia guilliermondii possessed a single component, high affinity active transport systems.     

A hybrid scatter search for the discrete time/resource trade-off problem in project scheduling

We develop a heuristic procedure for solving the discrete time/resource trade-off problem in the field of project scheduling. In this problem, a project contains activities interrelated by finish-start-type precedence constraints with a time lag of zero, which require one or more constrained renewable resources. Each activity has a specified work content and can be performed in different modes, i.e. with different durations and resource requirements, as long as the required work content is met. The objective is to schedule each activity in one of its modes in order to minimize the project makespan. We use a scatter search algorithm to tackle this problem, using path relinking methodology as a solution combination method. Computational results on randomly generated problem sets are compared with the best available results indicating the efficiency of the proposed algorithm.