农田塑料地膜污染及防治

IEECAS SKLLQG

黄土塬区3种豆科牧草对土壤水分的消耗利用研究

在田间完全旱作条件下采用3个密度和2种播种方式观察了3种多年生豆科牧草生长第2年对土壤水分的消耗利用情况。结果表明:苜蓿主要耗水深度在2~3 m,最深可达5 m,其中、高密度处理3 m以上土壤水分含量都在稳定田间持水量之下,已经开始形成土壤下伏干层;沙打旺耗水深度在0~2 m,最低含水量(11.61%)处于80~100 cm,在雨季可以恢复到稳定田间持水量之上;达乌里胡枝子主要耗水深度在1 m以上,最低含水量也在稳定田间持水量之上。单播沙打旺、苜蓿和达乌里胡枝子全生长期内对土壤水分的消耗分别为249.9、180.2和136.6 mm,水分利用效率分别是29.39、26.04和8.91 kg.mm-1.hm-2。混播、加大播种密度都会增加3种牧草土壤水分消耗,降低土壤储水量,提高干草产量和水分利用效率,但影响程度因牧草种类、播种方式以及不同的生长时段而异。

原油萃取汽提水中的酚

渣油催化裂化装置产生的含硫污水经汽提后虽脱除了大部分的硫、氮化合物，但仍含有较高浓度的酚类物质直接排入污水处理厂，其酚负荷约占全厂进水总酚的一半以上，极易造成对生物处理设施的冲击，导致活性污泥恶化，严重影响总排污水综合合格率。因此，在汽提水进入污水厂...

Development of nanodomain and fractal morphologies in solvent annealed block copolymer thin films

We have systematically studied the thin film morphologies of asymmetric polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer subjected to solvent vapors of varying selectivity for the constituent blocks. Upon a short treatment in neutral or PS-selective vapor, the film exhibited a highly ordered array of hexagonally packed, cylindrical microdomains. In the case of PEO selective vapor annealing, such ordered cylindrical microdomains were not obtained. instead, fractal patterns on the microscale were observed and their growth processes investigated. Furthermore, hierarchical structures could be obtained if the fractal pattern was exposed to neutral or PS selective vapor.

Nature of the ring-banded spherulites in blends of aromatic poly(ether ketone)s

The ring-banded spherulites in liquid crystalline poly(aryl ether ketone) (LC-PAEK) and poly(aryl ether ether ketone) (PEEK) blends with a higher content (>50%) of LC-PAEK are investigated by polarizing light microscopy (PLM) and atomic force microscopy (AFM) techniques. The results indicate that the light core and rings of the ring-banded spherulites under PLM are mainly composed of an LC-PAEK phase, while the dark rings consist of coexisting phases of PEEK and a small amount of LC-PAEK. The formation of the ring-banded spherulites is attributable to structural discontinuity caused by a rhythmic radial growth.

天津近岸台风暴潮漫滩数值模拟研究

中国是太平洋沿岸国家中频繁遭受风暴潮灾害的国家之一，提高风暴潮预报的准确性，可以直接减少海洋灾害造成的经济损失和人员伤亡，具有十分积极的重要意义。针对天津近岸海域的地形和易受风暴潮漫滩灾害侵袭的特点，本文基于对POM( Princeton Ocean Model)模式的改进，建立了天津近岸海域三维动边界风暴潮漫滩模型，并选择典型天气个例，对天津近岸区域台风影响下的风暴潮漫滩进行了数值模拟研究。 本文的计算建立在POM模式基础上，采用两重网格嵌套的方法，第一套网格对整个渤海海域进行固定边界风暴潮的数值模拟，第二套网格对天津近岸海域进行可变边界模拟。通过两套网格的合理衔接，大区域网格尽量覆盖风场范围，小区域网格细致刻画浅水区域，提高了风暴潮的模拟分辨率。 第二套网格的计算，采用干湿网格法，在POM模式中加入干湿点的判断，而岸界条件与固定边界模式一样，从而提高了模式的模拟精度，能够较真实地模拟出台风作用下风暴潮水位随岸线的移动。本文采用的Flather-Heaps干湿网格法，简单易行，不会增加程序的复杂度和计算量。 模式选取7203、8509、9216、9711号台风计算风暴潮漫滩水位变化，通过与塘沽站点实测数据的比较，计算增水曲线过程与实测结果吻合较好，基本能够真实反映天津近岸的风暴潮水位变化情况及漫滩范围。本文的研究结果验证了改进POM模式为动边界数值模型并应用于浅海区域的可行性。

Karyomorphology of Biebersteinia Stephan (Geraniaceae) and its systematic and taxonomic significance

The systematic and taxonomic position of Biebersteinia Stephan has long been in dispute. The present paper describes for the first time the karyomorphology of two species in Biebersteinia Stephan. Both species commonly showed the interphase nuclei of the simple chromocenter type and the mitotic prophase chromosomes of the interstitial type. The karyotype formulae of both B. heterostemon and B. odora were 2n=10=2m(2sec)+8sm(2sec), belonging to the 3A type of Stebbins' classification. The karyotype of this genus is recorded for the first time. The basic chromosome numbers of four of the five known species of Biebersteinia have been recorded as x=5. The combination of resting nuclei of the simple chromocenter type, mitotic prophase chromosomes of the interstitial type, two pairs of chromosomes with four obvious secondary constrictions at the mitotic prophase and metaphase stages, and the peculiar 3A karyotype in Biebersteinia can be regarded as the karymorphological marker of this genus. The karyomorphological data presented here do not support the traditional grouping of this genus in Geraniaceae. The unique karyomorphology of Biebersteinia justifies its familiar or ordinal status, which is congruent with embryological, anatomical, chemical and molecular data. The systematic position of Biebersteinia needs further study.

非完整自主车基于圆轨迹的道路避障

本文就四轮非完整自主车提出了一种基于圆轨迹的道路避障策略。先将道路上的障碍按照障碍距离自主车的远近划分层次,使一个层次的障碍能在自主车视场中全部出现。然后给出基于圆轨迹的避障算法,即自主车沿由自主车出发位姿和子目标点确定的圆弧轨迹走行。在此之前推导四轮非完整车的运动模型为提出避障策略的基础准备。尽量减小自主车在走行过程中运动状态的改变,基于圆轨迹避障策略能够很好地满足这一要求。最后引入代价函数,给出对于此方法的评价,体现了本方法的优越性。

自治式移动车路标识别系统

路标识别是自治式移动车（ALV）视觉系统的一个重要组成部分，它能校正内部导航系统的定位误差，引导ALV沿正确的行驶。本文给出了一种路标识别系统结构，并对系统各模块做了较为详尽的阐述。该系统是预测驱动，基于知识的分割识别系统，在模型匹配的识别方法中引入大量的有关地图和路标的先验知识。给出ALV的近似位置，该系统首先根据地图知识预测是否有路标存在并对可能出现的路标，预测其路标模型。然后对图像进行分割处理，抽取符号特征，得到图像模型。最后将图像模型与预测的路标模型相匹配，验证预测的正确性，给出识别结果。该系统的主要特点是：1）地图和路标的先验知识都以显式的形式表示，集中存于知识库中，知识库具有良好的人机接口。2）在面向目标的特征抽取过程中，引入大量的关于路标的先验知识，对不同类型的路标，用不同的模块完成特征抽取。3）用证据累积与空间推理实现匹配，其中证据累积由启发式贝叶斯匹配器完成。即使在图像模型与路标模型有一定差异的情况下，仍能很好地完成识别任务。该系统己在VICOM彩色图像处理系统和sum-3工作站上用C语言实现。目前，能对二类路标进行成功的识别。本文给出了实验结果及分析。

大型反倾岩体变形破坏机制及稳定性分析———以金沙江宽谷坝址龙蟠边坡为例

A large number of catastrophic accidents were aroused by the instability and destruction of anti-dip rock masses in the worldwide engineering projects, such as hydropower station, mine, railways and so on. Problems in relation to deformation and failure about anti-dip rock slopes are significant for engineering geology research. This dissertation takes the Longpan slope in the Jinsha River as a case to study the deformation mechanism of large-scale anti-dip rock masses and the slope stability analysis method. The primary conclusions are as follows. The Dale Reach of Jinsha River, from Longpan to the debouchment of Chongjiang tributary, is located in the southeastern margin of the Qinghai-Tibet Plateau. Longpan slope is the right embankment of Dale dam, it is only 26 km to the Shigu and 18 km to Tiger Leaping Gorge. The areal geology tectonic structures here area are complicated and blurry. Base on the information of geophysical exploration (CSAMT and seismology) and engineering geological investigation, the perdue tectonic pattern of Dale Reach is put forward for the first time in this paper. Due to the reverse slip of Longpan fault and normal left-rotation of Baihanchang fault, the old faulted valley came into being. The thick riverbed sediments have layered characters of different components and corresponding causes, which attribute to the sedimentary environments according with the new tectonic movements such as periodic mountain uplifting in middle Pleistocene. Longpan slope consists of anti-dip alternate sandstone and slate stratums, and the deformable volume is 6.5×107m3 approximately. It was taken for an ancient landslide or toppling failure in the past so that Dale dam became a vexed question. Through the latest field surveying, displacement monitoring and rock masses deforming characters analyses, the geological mechanism is actually a deep-seated gravitational bending deformation. And then the discrete element method is used to simulate the deforming evolution process, the conclusion accords very well with the geo-mechanical patterns analyses. In addition strength reduction method based on DEM is introduced to evaluate the factor of safety of anti-dip rock slope, and in accordance with the expansion way of the shear yielding zones, the progressive shear failure mechanism of large-scale anti-dip rock masses is proposed for the first time. As an embankment or a close reservoir bank to the lower dam, the stability of Longpan slope especially whether or not resulting in sliding with high velocity and activating water waves is a key question for engineering design. In fact it is difficult to decide the unified slip surface of anti-dip rock slope for traditional methods. The author takes the shear yielding zones acquired form the discrete element strength reduction calculation as the potential sliding surface and then evaluates the change of excess pore pressure and factor of stability of the slope generated by rapid drawdown of ponded water. At the same time the dynamic response of the slope under seismic loading is simulated through DEM numerical modeling, the following results are obtained. Firstly the effective effect of seismic inertia force is resulting in accumulation of shear stresses. Secondly the discontinuous structures are crucial to wave transmission. Thirdly the ultimate dynamic response of slope system takes place at the initial period of seismic loading. Lastly but essentially the effect of earthquake load to bringing on deformation and failure of rock slope is the coupling effect of shear stresses and excess pore water pressure accumulation. In view of limitations in searching the critical slip surface of rock slope of the existing domestic and international software for limit equilibrium slope stability analyses, this article proposes a new method named GA-Sarma Algorithm for rock slope stability analyses. Just as its name implies, GA-Sarma Algorithm bases on Genetic Algorithm and Sarma method. GA-Sarma Algorithm assumes the morphology of slip surface to be a broken line with traceability to extend along the discontinuous surface structures, and the slice boundaries is consistent with rock mass discontinuities such as rock layers, faults, cracks, and so on. GA-Sarma Algorithm is revolutionary method that is suitable for global optimization of the critical slip surface for rock slopes. The topics and contents including in this dissertation are closely related to the difficulties in practice, the main conclusions have been authorized by the engineering design institute. The research work is very meaningful and useful for the engineering construction of Longpan hydropower station.

Asesoría asistencia técnica y transferencia tecnológica en el desarrollo de nuevos productos prototipos esmaltados. Casa Colombiana 2004-2005 : proyecto cadena productiva de la cerámica, departamento del Huila.

89 hojas.

Cuaderno de diseño e informe final. Regional Santa Fe de Bogotá, evaluación de productos y asesorías puntuales gestión de producción, gestión oficina de diseño y actividades.

150 hojas.

Pricing Algorithms For a Two-sided Internet Advertisement Market

The Google AdSense Program is a successful internet advertisement program where Google places contextual adverts on third-party websites and shares the resulting revenue with each publisher. Advertisers have budgets and bid on ad slots while publishers set reserve prices for the ad slots on their websites. Following previous modelling efforts, we model the program as a two-sided market with advertisers on one side and publishers on the other. We show a reduction from the Generalised Assignment Problem (GAP) to the problem of computing the revenue maximising allocation and pricing of publisher slots under a first-price auction. GAP is APX-hard but a (1-1/e) approximation is known. We compute truthful and revenue-maximizing prices and allocation of ad slots to advertisers under a second-price auction. The auctioneer's revenue is within (1-1/e) second-price optimal.

Catalyst, additive and substrate effects in intramolecular aromatic additions of alpha-diazoketones

This thesis is focused on transition metal catalysed reaction of α-diazoketones leading to aromatic addition to form azulenones, with particular emphasis on enantiocontrol through use of chiral copper catalysts. The first chapter provides an overview of the influence of variation of the substituent at the diazo carbon on the outcome of subsequent reaction pathways, focusing in particular on C-H insertion, cyclopropanation, aromatic addition and ylide formation drawing together for the first time input from a range of primary reports. Chapter two describes the synthesis of a range of novel α-diazoketones. Rhodium and copper catalysed cyclisation of these to form a range of azulenones is described. Variation of the transition metal catalyst was undertaken using both copper and rhodium based systems and ligand variation, including the design and synthesis of a novel bisoxazoline ligand. The influence of additives, especially NaBARF, on the enantiocontrol was explored in detail and displayed an interesting impact which was sensitive to substituent effects. Further exploration demonstrated that it is the sodium cation which is critical in the additive effects. For the first time, enantiocontrol in the aromatic addition of terminal diazoketones was demonstrated indicating enantiofacial control in the aromatic addition is feasible in the absence of a bridgehead substituent. Determination of the enantiopurity in these compounds was particularly challenging due to the lability of the products. A substantial portion of the work was focused on determining the stereochemical outcome of the aromatic addition processes, both the absolute stereochemistry and extent of enantiopurity. Formation of PTAD adducts was beneficial in this regard. The third chapter contains the full experimental details and spectral characterisation of all novel compounds synthesised in this project, while details of chiral stationary phase HPLC and 1H NMR analysis are included in the appendix.