基于变权灰色关联法的长江荆南三口地区水资源短缺程度分析

对荆南三口地区水资源短缺程度进行分析研究,为实现区域水资源可持续合理利用提供科学依据。在水资源短缺评价研究中,前期研究成果大多采用常权法确定评价指标,致使评价指标产生状态失衡。将变权理论引入到水资源短缺程度分析中,从而确定评价指标变权重,并结合灰色关联法,构建水资源短缺程度分析的变权灰色关联法模型并加以应用。最终得出荆南三口地区三县的水资源短缺程度均为轻度缺水,其缺水程度排序为:华容县南县安乡县。利用变权灰色关联法计算水资源短缺程度,方法可行,结果合理,满足了评价指标均衡性要求。     

可双固化树枝形聚酰胺-胺树脂的合成及其涂膜性能研究

探讨了以乙二胺与丙烯酸甲酯交替反应，制备了1．5，2．5代树枝形聚酰胺一胺树脂（PAMAM），对其用甲基丙烯酸缩水甘油酯（GMA）和γ-氨丙基三乙氧基硅烷进行了改性，使其能够紫外光固化和潮气固化。热分析考查了玻璃化温度和热稳定性，并进行了硬度、光泽、光固化速度、潮气固化速度、附着力、柔韧性等测试。     

The comparative effect of a mixed urea,ammonium nitrate,ammonium sulphate granular formulation on the efficiency of N recovery by perennial ryegrass

The¹⁵N isotope was used to study the mode of action of individual nitrogen sources in a 30% urea:30% ammonium nitrate: 10% ammonium sulphate:30% filler (w/w) granular fertilizer for perennial ryegrass in a greenhouse pot experiment. The fertilizer consisted of two types of granules, one containing 80% urea and 20% filler and the second containing 48% ammonium nitrate (AN), 16% ammonium sulphate (AS) and 36% filler. In addition the effect of dolomite compared with silica as the filler was investigated on nitrogen recovery from the 30:30:10:30 formulation.Dolomite adversely affected the recovery of nitrate N from the system and evidence suggested that MgCO₃ was the active component. Granules containing dolomite resulted in a lower dry-matter yield than those containing silica, however the difference was not significant as nitrate contributed only 20% of the N in the formulation. AN gave the greatest DM yield and urea the lowest with AS being intermediate. The¹⁵N budget in shoots, roots and soil indicated that only 65% of the N from urea was recovered at the end of the experiment compared with 86% for AN and 91% for AS. The dry-matter yield of the 30:30:10:30 formulation using silica as the filler was intermediate between urea and AN; however, the apparent N recovery was significantly higher than expected from the sum of the individual components. The use of¹⁵N labelling indicated that using separate granules for ammonium N and urea the recovery of urea was improved by 11% in the triple N mixture when both AN and AS were present in the second granule compared to the recovery on its own. The enhanced recovery of urea appeared to be a function of AN and AS acting together as neither source in double combination with urea had any effect on urea N recovery.Urea enhanced the recovery of nitrate N by 10% but decreased the recovery of AS by 6% (in the 30:30:10:30 formulation) in comparison with the single sources on their own. The results indicate that interactions can occur between N sources even when they are physically separated by being in different granules.     

Effects of soil solution on the dynamics of N2O emissions: a review

In this review, which consists of two parts, major interactions between nitrous oxide (N₂>O) and soil solution are described. In the first part, as an introduction, concentrations of dissolved N₂>O in different aqueous systems are summarized. An inventory of data on maximal N₂>O concentrations in soil solution (up to 9984 g N₂>O-N l^–1>) and in soil air (up to 8300 ppm) from literature is presented. The peak N₂>O concentrations represent a N₂>O supersaturation in the soil solution up to 30000 times with respect to ambient air and a soil air N₂>O concentration about 25000 times higher than in the atmosphere. The main physico–chemical parameters (solubility, diffusion) controlling N₂>O distribution between soil solution and soil air are outlined. The influences of cultivation practice, nitrogen turnover, water content and temperature on N₂>O a ccumulation in soil solution and soil air are reviewed. In the second part some models of N₂>O dynamics in soils are discussed with emphasis on N₂>O transport processes. A simple qualitative scheme is developed to categorize the effects of the soil solution on N₂>O dynamics in soils. In this scheme the temporary, intensive N₂>O oversaturation of the soil solution is interpreted as a result of gas diffusion inhibition by water (barrier function of soil solution) resulting in an accumulation of N₂>O. In addition, N₂>O supersaturation is an indication that transitory much N₂>O can be stored in the soil solution (storage function of soil solution). Where the soil solution flows up-, down- or sidewards it can act as a relevant transport medium for dissolved N₂>O (transport function of soil solution). This scheme is applied to examples from the literature.     

高含水率杨木单板室温胶合的脲醛树脂胶研究

在实验室条件下 ,以传统脲醛树脂胶的生产工艺为基础 ,加用氨基取代羧酸类化合物。新配方制得脲醛树脂胶 ,用DSC分析了树脂固化反应热过程 ,对含水率在 12 % -2 0 %杨木单板进行了室温胶合研究     

Analysis of four Monte Carlo methods for the solution of population balances in dispersed systems

Monte Carlo (MC) constitutes an important class of methods for the numerical solution of the general dynamic equation (GDE) in particulate systems. We compare four such methods in a series of seven test cases that cover typical particulate mechanisms. The four MC methods studied are: time-driven direct simulation Monte Carlo (DSMC), stepwise constant-volume Monte Carlo, constant number Monte Carlo, and multi-Monte Carlo (MMC) method. These MC's are introduced briefly and applied numerically to simulate pure coagulation, breakage, condensation/evaporation (surface growth/dissolution), nucleation, and settling (deposition). We find that when run with comparable number of particles, all methods compute the size distribution within comparable levels of error. Because each method uses different approaches for advancing time, a wider margin of error is observed in the time evolution of the number and mass concentration, with event-driven methods generally providing better accuracy than time-driven methods. The computational cost depends on algorithmic details but generally, event-driven methods perform faster than time-driven methods. Overall, very good accuracy can be achieved using reasonably small numbers of simulation particles, O(10³), requiring computational times of the order 10²−10³ s on a typical desktop computer.     

福建水口全平衡垂直升船机调试技术研究与实践

全平衡垂直升船机是解决高坝通航问题的有效途径,而升船机在正式投入运行前必须通过严格的设备调试。介绍了福建水口全平衡垂直升船机在调试过程中所发现的一系列问题及解决方法:包括技术参数整定、优化逻辑闭锁条件、人机界面和数据库功能等。目前,水口电站升船机设备运行状态符合设计要求。根据水口升船机调试的实践经验,对钢丝绳卷扬提升式全平衡垂直升船机调试的关键技术进行了总结,以期对国内升船机建设提供一定的借鉴价值。     

聚丙烯接枝马来酸酐增容聚酰胺6／聚丙烯体系吸湿性能及力学性能的研究

以聚丙烯接枝马来酸酐(PP-g-MAH)为相容剂，利用其与聚酰胺6(PA6)在共混过程中的反应增容作用，实现了与聚丙烯(PP)之间的相容性共混，改变其用量，制备了系列具有不同组成的PA6／PP合金，研究了不同组成合金材料的吸湿性能及其在干态和充分吸湿状态时的冲击强度和拉伸性能。结果表明，向PA6／PP合金体系中加入相容剂PP-g-MAH后，可以改善合金的相界面，形成相容性的合金结构，明显降低合金材料的吸湿量及吸湿速率，但进一步增大相容剂PP-g-MAH的用量时，只能明显降低合金材料吸湿过程初期的吸湿速率，不能进一步显著降低合金材料的吸湿量。在相容剂PP-g-MAH用量一定时，随着PA6／PP合金体系中PA6组分含量的提高，合金在干、湿态条件下的冲击强度、拉伸强度、断裂伸长率均呈近似线性变化。对于具有相同基本组成的合金，随着相容剂PP-g-MAFI用量的增加，材料在干、湿态条件下的拉伸强度均有提高，杨氏模量则在干态时有所提高，在湿态时影响不显著，在干、湿态时断裂伸长率以及冲击强度均没有产生显著影响。     

浅谈当前环境保护工作现状及对策

随着经济的飞速发展,我国的环境状况在不断恶化。就目前的环境现状、环境污染问题和环境保护工作现状进行了详细分析和阐述,并对环境保护工作提出参考和建议。     

Integral approximation—an approach to reduced models for particulate processes

In this contribution, a model reduction technique for population balance systems describing particulate processes is presented. This technique is based on integral approximation and allows the derivation of highly accurate moment models. In contrast to other model reduction methods which can be found in literature, this integral approximation technique can be applied for arbitrarily complex phenomena specifications. The applicability of the presented method will be demonstrated for different example processes by comparing the dynamic behavior of the original population balance models with those of the derived reduced models of moments.