The performance of closed reactor grade plutonium-thorium fuel cycles in reduced-moderation pressurised water reactors

The production of long-lived transuranic (TRU) waste is a major disadvantage of fission-based nuclear power. Previous work has indicated that TRU waste can be virtually eliminated in a pressurised water reactor (PWR) fuelled with a mixture of thorium and TRU waste, when all actinides are returned to the reactor after reprocessing. However, the optimal configuration for a fuel assembly operating this fuel cycle is likely to differ from the current configuration. In this paper, the differences in performance obtained in a reduced-moderation PWR operating this fuel cycle were investigated using WIMS. The chosen configuration allowed an increase of at least 20% in attainable burn-up for a given TRU enrichment. This will be especially important if the practical limit on TRU enrichment is low. The moderator reactivity coefficients limit the enrichment possible in the reactor, and this limit is particularly severe if a negative void coefficient is required for a fully voided core. Several strategies have been identified to mitigate this. Specifically, the control system should be designed to avoid a detrimental effect on moderator reactivity coefficients. The economic viability of this concept is likely to be dependent on the achievable thermal-hydraulic operating conditions. © 2012 Elsevier Ltd. All rights reserved.

Generalization in Adaptation to Stable and Unstable Dynamics

Humans skillfully manipulate objects and tools despite the inherent instability. In order to succeed at these tasks, the sensorimotor control system must build an internal representation of both the force and mechanical impedance. As it is not practical to either learn or store motor commands for every possible future action, the sensorimotor control system generalizes a control strategy for a range of movements based on learning performed over a set of movements. Here, we introduce a computational model for this learning and generalization, which specifies how to learn feedforward muscle activity in a function of the state space. Specifically, by incorporating co-activation as a function of error into the feedback command, we are able to derive an algorithm from a gradient descent minimization of motion error and effort, subject to maintaining a stability margin. This algorithm can be used to learn to coordinate any of a variety of motor primitives such as force fields, muscle synergies, physical models or artificial neural networks. This model for human learning and generalization is able to adapt to both stable and unstable dynamics, and provides a controller for generating efficient adaptive motor behavior in robots. Simulation results exhibit predictions consistent with all experiments on learning of novel dynamics requiring adaptation of force and impedance, and enable us to re-examine some of the previous interpretations of experiments on generalization. © 2012 Kadiallah et al.

Stabilization of periodic orbits in a wedge billiard

This paper introduces a stabilization problem for an elementary impact control system in the plane. The rich dynamical properties of the wedge billiard, combined to the relevance of the associated stabilization problem for feedback control issues in legged robotics make it a valuable benchmark for energy-based stabilization of impact control systems.

A simple closed aquatic ecosystem (CAES) for space

A closed aquatic ecosystem (CAES) was developed to stud), the effects of microgravity on the function of closed ecosystems aboard the Chinese retrieved satellite and on the spacecraft SHENZHOU-II. These systems housed a small freshwater snail (Bulinus australianus) and an autotrophic green algae (Chlorella pyrenoidosa). The results of the test on the satellite were that the concentration of algae changed little, but that the snails died during the experiments. We then sought to optimize the function of the control system, the cultural conditions and the data acquisition system and carried out an experiment on the spacecraft SHENZHOU-II. Using various sensors to monitor the CAES, real-time data regarding the operation of the CAES in microgravity was acquired. In addition, all on-board Ig centrifuge was included to identify gravity-related factors. It was found that microgravity is the major factor affecting the operation of the CAES in space. The change in biomass of the primary producer during each day in microgravity was larger than that of the control groups. The mean biomass concentration per day in the microgravity group decreased, but that of the control groups increased for several days and then leveled off. Space effects on the biomass of a primary producer may be a result of microgravity effects leading to increasing metabolic rates of the consumer combined with decreases in photosynthesis. (c) 2007 COSPAR. Published by Elsevier Ltd. All rights reserved.

Micronutrient niacin addition to enhance biological treatment of textile wastewater

Micronutrients play an important role in biological processes for wastewater treatment. Many industrial wastewaters lack in nutrients required for microbial growth, and this is one of the problems at many activated sludge plants treating them. In this study, the effects of the micronutrient niacin on the COD removal rates of textile wastewater, together with the effect of Mixed Liquor Suspended Solids (MLSS) on niacin, were studied. Certain improvement effects were found on the removal rates of COD, when 0.5 similar to 2.0 mg/L niacin was added to the textile wastewater. The optimal concentration of niacin was 1.0 mg/L, which was continuously added during textile wastewater treatment, and removal rates were 1.31 times compared to those of the control system. The concentration of MLSS was probably one of the factors influencing treatment efficiency, and the biological performance of treatment system could be optimized through micronutrient niacin supplements.

面向ETL过程的数据质量控制系统的设计与实现

ETL过程是一个从分布数据源(包括数据库、应用系统、文件系统等)抽取数据，进行转换、集成和传输，并最终加载到目标系统的过程。传统的ETL过程主要服务于数据仓库(Data Warehouse)，属于企业决策支持系统的一部分。随着数据集成技术的发展和轻量级的数据集成中间件的出现，ETL过程广泛应用于企业数据集成与数据交换系统。在ETL过程中，数据质量控制是一个极为重要的基本组件和功能，它对集成中的数据进行检测、转换、清洗，以防止“脏”数据进入目标系统。在ETL过程中如果缺少对数据质量的有效控制，就会导致数据集成项目无法圆满实现目标或彻底失败。 针对ETL过程中存在的数据质量问题，设计并实现面向ETL过程的数据质量控制系统，是本文研究的重点。论文通过对ETL过程中各阶段可能产生的数据质量问题进行了分类，并对质量控制需求建模，提出一个面向ETL过程的数据质量控制框架，该框架通过对源端数据的分析来指导ETL的设计，通过灵活、可配置、可扩展的数据处理机制实现数据的过滤、转换与清洗，并支持对数据质量处理全过程进行监控。在该框架基础上，论文特别在灵活的数据处理机制、数据分析、数据过滤和数据清洗四个方面进行了探讨。在数据处理机制方面，提出了基于插件元模型的数据处理机制，该机制可以满足用户对数据过滤、数据转换与数据清洗等功能的各种定制需求，并具有较强的可扩展性；在数据分析方面，根据字段类型对数据进行分类统计，并针对大数据量统计分析问题，提出了可自动配置的不同数据统计策略；在数据过滤方面，通过将抽取数据的SQL语句重写的方式，过滤不满足完整性约束的元组；在数据清洗方法方面给出了一种利用统计信息动态确定属性相似度权重的方法，对基于字段的相似记录检测算法的领域无关算法进行了改进，提高了数据检测的准确性。在上述工作基础上，在数据集成中间件OnceDI中设计并实现了数据质量控制系统，并在设计中通过设计模式的应用增强系统的可扩展性。

中药处方配伍监控系统的设计与实现

医院信息系统(hospital information system,HIS)作为医院信息化建设的重要组成部分越来越受到社会的重视,已经进入一个高速发展的阶段。但是作为诊疗过程的一个重要组成部分-药物处方治疗,在HIS中却缺少必要的监控与指导。在HIS标准化推进的同时,更应该对其深度和广度进行研究,结合软件工程的设计思想,基于面向对象的开发方法,设计开发了“中药处方配伍”监控系统,提供了临床用药指导功能,使其作为HIS的一个子系统能够实时的对医生处方进行监控,使临床医药人员记得更多、更准、更细,以降低药源性疾病,提高用药质量,加强用药管理,避免医疗纠纷。

一种分布式转发基站测控系统的研究与实现

布式监测系统(DCS)在许多领域具有重要的应用价值.针对目前分布式监测系统造价高、运行不稳定等问题,该文提出了一种解决方案--基于多种通讯链路的分布式转发基站监测系统.该文详细介绍了阐述了该监测控制系统的工作原理,并对监测控制系统的结构(包括软件的结构和硬件系统的结构)进行了具体地说明,然后详细描述了监控系统软件、硬件以及通讯协议的设计与实现;文章最后,对基于该系统的一个成功应用--无线寻呼基站无人测控系统的实现作了介绍.无线寻呼基站运行实践中所表现出的低成本、高性能的特点进一步验证了该方案的可实施性.

我国的风电技术和风电发展

发展风力发电是我国能源战略的一项重要内容。文章首先介绍了我国风电利用的总体状况；然后从风机叶片制造、控制系统及整机制造等方面，详述了现阶段我国风电设备的基本状况；最后对我国风电发展障碍进行了分析。并提出了相关建议。

车载式变量施药机控制系统设计与试验

施药控制是提高作业质量、减少化学污染、降低生产成本的关键技术。该文基于单片机AT89C52,采用滞环控制法,设计了一种车载式变量施药机控制系统。该系统能够根据施药机行走速度自动变更喷药量,实现施药量不变。试验表明:加速度小于0.4m/s2时,实际施药量与设定施药量之间的误差不超过8%,且雾化效果良好、生产效率高,还可以减少农药的残留和对环境的污染,能够满足农业生产的需要。

氟化物无机纳米粒子的制备及其稀土掺杂体系的光谱性质

对于纳米复合材料来说，首要解决的问题就是光散射。光散射现象主要是粒子尺寸以及粒子与基质材料折射率的差异引起的。对于小粒子（＜25nm），纳米粒子与基质材料之间的折射率差异不会造成明显的光散射现象，但对于较大粒子来说，为避免明显的光散射现象的发生，二者之间的折射必须吻合。由瑞利散射公式计算得知，当粒子直径大到100nm时，粒子与基质之间的折射率差值必须在0.02之内。因此，解决复合材料光散射问题有两种途径：尽量减小纳米粒子尺寸；选择折射率匹配良好的氟化物和聚合物分别作光学活性组分的基质和材料的基底材料。由于微乳液法合成纳米粒子条件温和、设备简单，所合成纳米粒子尺寸可控。本文首先研究了微乳液结构和性质，采用微乳液法合成氟化物纳米粒子，并研究了其稀土掺杂体系的光学性质。对于微乳液结构和性质的研究，本文绘制了十六烷基三甲基嗅化钱（CTAB）／正丁醇（n-C_4H_9OH）／正辛烷（n-C_8H_(18)）／水（或NH4F溶液、或Ba(NO_3)_2溶液、或KNO_3-Mg(NO_3)_2混合溶液）四组分微乳体系的三元相图，观察了电导率随水（或豁溶液）含量变化的规律，很好地印证了微乳液体系的相行为。实验发现，在这四个四元体系的相图中，Ba(NO_3)_2溶液体系的油包水区域面积最大，纯水体系水包油微乳区面积最小，我们分析认为水包油微乳区面积的变化是由于体系中加入离子后对表面活性剂阳离子的静电作用所引起的。采用十六烷基三甲基澳化按（CTAB）／正丁醇／正辛烷／水体系合成了KMgF_3以及KMgF_3:Eu~(2+)纳米粒子。XRD分析表明所合成纳米粒子为立方KMgF_3单相；环境扫描电子显微镜（ESEM）分析得到所合成KMgF_3:Eu~(2+)纳米粒子粒径约为20nm。KMgF_3:Eu~(2+)纳米粒子光谱研究发现其发射峰位于360nm附近，其激发峰位于250nm附近，较KMgF_3:Eu~(2+)单晶的激发峰峰蓝移了约80nm。对KMgF_3:Eu~(2+)纳米粒子激发峰蓝移的机理进行了初步探讨。采用CTAB/2-丁醇／水微乳体系合成出球形BaF_2纳米粒子，XRD和ICP数据显示样品为纯BaF_2相；FTIR谱图证明体系中没有有机物质的存在。将由纳米粒子分散到水中所形成的胶体滴到铜网上，干燥后发现所合成粒子有自组装的特性摘要且粒子自组装形状因粒子尺寸以及样品制备过程而异。粒子的自组装完全是自发的，没有任何的化学试剂对粒子进行包覆，也没对粒子施加除超声分散之外的任何外力。当将一滴胶体溶液直接滴到铜网上，干燥后我们得到粒子的圆形自组装，较大粒子分布在外围形成一个圆，较小粒子分布在圆的内部形成环；我们将一滴BaF_2纳米粒子胶体溶液滴加到铜网上，待干燥后滴加第二滴，重复此操作两次，这样铜网上共滴加的胶体溶液为3滴，此时我们得到粒子的双平行线型组装；直接滴加3滴BaF_2纳米粒子胶体溶液到铜网上，干燥后得粒子的桶状自组装。采用CTAB／正丁醇／正辛烷／水体系于35℃下合成带有枝晶的BaF_2纳米立方。这些枝晶生长在纳米立方的两个相邻面之间呈片状弧形。粉末XRD分析表明，体系为BaF_2单相且结晶良好；用扫描电子显微镜（SEM）对粒子进行分析发现，所得纳米立方边长为400-450nm；FTIR分析表明，经处理后样品中没有有机物质残存；对枝晶的能谱分析（EDS）分析表明，枝晶中只有Ba和F两种元素而未发现C元素存在。这说明，立方上所生长的枝晶为纯BaF_2产物而非有机物质所形成的。试验发现，所合成粒子的尺寸和形状依赖于反应温度和反应时间。采用士一述体系，于25℃下反应，可得到横截面边长40nm，长200nm的立方柱状纳米粒子，并且未见枝晶。从不同反应时间所合成粒子的形状上我们可以估计纳米立方以及枝晶的住：长过程。采用CTAB／正丁醇／正辛烷／水体系首次合成了BaF_2:Er纳米粒子，并研究了掺杂浓度对粒子红外发光的影响，XRD分析表明所合成BaF_2:Er纳米粒子为BaF_2立方相，物相纯净，结晶良好；TEM分析表明在掺杂浓度为6mol％时，粒子尺寸为15-20nm，士曾大粒子的掺杂浓度（8，10和12mol％）下，其尺寸和形状无明显改变，但粒子团聚现象严重。粒子在氢离子激光器488nm激发下的荧光（PL）光谱显示，随粒子掺杂浓度的增大，其发光强度增强，半峰宽加宽。研究了BoF_2:Er纳米粒子尺寸对其发光强度的影响，通过调节体系中水含量以达到控制粒子尺寸的目的。在体系中水含量。分别为5，8，15的条件「分别合成出平均粒径约为8，10和20.5nm的粒子。从粒子的激光粒度分布图中我们可得到粒子的平均尺寸。从粒子的XRD图中我们可以发现，随粒子粒径的减小，粉末的衍射峰出现偏移的情况。对于不同种纳米粒子，粒子粒径越小，衍射峰偏移越严重；对于相同的粒子，衍射角度越大，衍射峰偏移的越严重。从三种粒子的红峰的半峰宽和有效半峰宽越宽，对于8nm粒径的粒子，我们得到其最大半峰宽为145nm或有效半峰宽173nm。而且随粒子粒径的减小，其发射峰出现红移的现象。采用CTAB／正丁醇／正辛烷／水体系首次合成了CeF_3以及掺杂浓度为17，25，30，42和50mol％的CeF_3:Lu纳米粒子。XRD分析表明，所合成纳米粒子为CeF_3六角相，物相纯净，结晶良好，即使在高的掺杂浓度下（50mol％）体系中一也无其他杂质相的存在。环境扫描电子显微镜（ESEM-FEG）分析表明，所合成CeF_3纳米粒子粒径为巧一20nm，Lu的掺入对粒子的形状和尺寸影响不明显，但在较高的掺杂浓度下粒子团聚现象严重。粒子的荧光光谱表明，CeF_3以及Lu：CeF_3纳米粒子在254nm的激发波长下的发射光谱从290nm到400nm的宽带发射，发射峰位于325nm，较单晶体的发射峰红移约30nm；Lu的掺入有利于提高CeF_3纳米粒子的发光强度，随Lu掺入量的增大，粒子的发光强度出现先增后减的情况，在掺杂浓度为30mol％时，我们得到CeF_3纳米粒子的最大发射，但在50mol％的掺杂浓度下的粒子的发射强度仍要比未掺杂体系的发光强度要强。325nln监测粒子的激发光谱是从200nm到350nm的宽带吸收，激发峰峰位于260nm左右。比CeF_3单晶体的280nm激发峰蓝移了20nm左右。而且粒子的激发光谱中未见长波方向上的肩峰，说明粒子中CeF_3纳米粒子结晶良好，且体系中氧含量低。采用自创建一步原位聚合的方法合成了聚合物包覆的纳米粒子，并采用本体聚合的方法合成复合材料。综上所述，本文采用微乳液法合成了不同的氟化物纳米粒子，并研究了其稀土掺杂体系的光学特性，为聚合物基复合材料的制备以及应用奠定了可靠的实验基础。

Single steady frequency and narrow line width external cavity semiconductor laser

A single longitudinal mode and narrow line width external cavity semiconductor laser is proposed. It is constructed with a semiconductor laser, collimator, a flame grating, and current and temperature control systems. The one facet of semiconductor laser is covered by high transmission film, and another is covered by high reflection film. The flame grating is used as light feedback element to select the mode of the semiconductor laser. The temperature of the constructed external cavity semiconductor laser is stabilized in order of 10(-3)degreesC by temperature control system. The experiments have been carried out and the results obtained-the spectral fine width of this laser is compressed to be less than 1.4MHz from its original line-width of more than 1200GHz and the output stability (including power and mode) is remarkably enhanced.

An investigation on fiber coupled polymer waveguide for electro-optic modulator

A novel crosslinkable polyurethane is used as the core layer of the electro-optic(E-O) modulator. The refractive index and dispersion of this material have been detected by analyzing the F-P oscillation in transmission spectra. Calculated results from the effective index method are given to design the Mach-Zehnder and straight 5-layer ridge wave-guide device (including the metal electrodes). With light at 1.31 mum being fiber coupled into waveguide, the mode properties of these devices have been demonstrated in a micron control system. The guided mode is accordant with the theoretical analysis.