基于改进的自适应渐消UKF机床主轴热平衡试验

数控机床的主轴热平衡试验是进行热误差建模和补偿的必要手段,是准确获得数控机床主轴的热敏感点、温度场和热位移以及热平衡时间等热态特性的方法。本文提出一种基于改进的自适应渐消无迹卡尔曼滤波(Adaptive fading unscented Kalman filter,AFUKF)的快速辨识机床主轴选点温升的方法。首先,在标准UKF中引入渐消因子,使用残差归一化自动更新渐消因子,并将其引入增益矩阵,增强测量值在计算中的权重;其次,通过使用自适应规则,动态调整过程噪声和测量噪声协方差阵,减少外部扰动对温升预测的影响,以获得更好的滤波性能。仿真结果表明,提出的机床主轴温升快速辨识方法可以在很短的时间内预测选点的温升,且预测结果与热平衡试验结果吻合,验证了本文方法的可行性和有效性。     

基于WA-SVM的流域降雨序列预测研

为了提高降雨中长期预测精度，将小波分析和支持向量机回归方法引入水文序列预测领域，给出了两种方法的思路和特点。在此基础上，尝试建立了基于小波分析-支持向量机（WA-SVM）的降雨量序列预测模型。通过小波分解，将原始复杂的降雨序列分解到不同的频率层次，对每层得到的分解序列分别采用支持向量机回归方法进行预测，最后合成原始序列的预测值。将该模型应用于实际流域月降雨量预测，并与单独支持向量机回归方法预测结果进行比较，表明该方法预测精度有明显提高。     

某数控车床开展的主轴温升及热变形测试研究

文章针对某型号数控车床开展了主轴箱温升以及热变形的测试分析,通过对主轴箱温升及主轴热变形的测试分析获得该产品主轴箱的热平衡温度、热平衡时间以及主轴的热漂移最大值。测试结论使设计人员对该数控车床主轴箱热特性有了更全面的了解,并为结构改进提供了有利的数据支撑。     

基于BA-LSSVM模型的月径流预测方法

针对最小二乘支持向量机模型传统参数选择方法费时且效果差的问题,利用蝙蝠算法的模型简单、快速收敛和全局搜索能力强的特点,优化模型的正则化参数和核函数参数,对水文时间序列建立最小二乘支持向量机预测模型。基于西江流域内的柳州水文站2000-2014年月径流资料对模型进行训练和预测,并与使用粒子群算法优化参数确定的最小二乘支持向量机模型,网格搜索及交叉验证优选参数确定的最小二乘支持向量机模型及BP神经网络模型进行比较。计算结果表明,基于蝙蝠算法优化最小二乘支持向量机模型具有很好的适用性和较高的预测精度,为利用最小二乘支持向量机模型解决非线性的水文时间序列问题提供了新的方向。     

基于灰色关联分析的支持向量机需水预测研究

近年来需水预测一直被高度重视,由于实际需水预测涉及因素众多难以考虑全面、历史资料的局限性以及需水变化影响因素考虑不足等,各种需水预测方法均存在一定局限性,导致预测结果与实际用水量有较大差别.针对以上问题,考虑采用灰色关联分析与支持向量机结合的方法进行需水预测,根据灰色关联分析方法辨识得到的各类用水主要影响因素,构建支持向量机需水预测模型.以郑州市实际用水量为例,对各部门用水分别建立基于灰色关联分析的支持向量机非线性需水预测模型,结果表明,此方法用于需水预测能够比较全面的考虑需水量影响因子,预测结果精度较高,可作为小样本情况下一种较好的需水预测方法.     

支持向量回归机在水质预测中的应用与验证

以干旱区浅水湖泊乌梁素海的多年实测pH值为例,在分析支持向量回归机算法（ε-SVR）核函数选取的基础上进行了回归分析及预测,并与线性回归、BP神经网络、RBF网络等算法进行了比较。研究结果显示：：（1） 基于径向基核的支持向量回归机模拟效果优于其它核函数;（2）ε-SVR模拟结果与线性回归（LR）、BP神经网络和RBF网络等算法模拟结果相比,其拟合精度与预测精度均比其它三种方法要高。计算结果充分证明了支持向量回归机有较强的学习能力和泛化能力且该方法可以应用于水质预测研究。     

基于最优权系数组合建模的数控机床热误差在线补偿

针对数控机床热误差建模具有小样本、数据离散的特点,提出一种综合灰色预测和最小二乘支持向量机的热误差在线组合建模方法。根据机床温度和热误差的实验数据,分别建立热误差的灰色模型和最小二乘支持向量机模型,并通过加权系数将两者进行组合。以提高热误差的实测值和组合模型预测值之间的灰色综合关联度为目标,对模型的加权系数进行优化。在一台高架桥式龙门加工中心上进行建模实验,结果表明数控机床热误差最优权系数组合建模方法精度高、泛化能力强,优于灰色预测、最小二乘支持向量机和多元线性回归3种建模方法。利用该方法构建的预测模型进行机床热误差在线补偿,可有效减小热误差对机床加工精度的影响。     

基于小波变换和SVR模型的陀螺仪故障预测

为了准确可靠地预测陀螺仪的故障,提出一种基于小波变换和支持向量回归机的陀螺仪故障诊断和预测方法。首先,利用小波分析和支持向量机对陀螺仪故障特征进行提取,然后建立SVR的故障预测模型,最后基于实验测得的陀螺仪振动数据对该预测模型进行了仿真验证,结果显示该算法预测效果良好,是一种有效的陀螺仪故障预测算法。     

基于支持向量机的水质预测应用实例

水质预测作为水环境污染控制的重要手段,能够预测水质的变化趋势,从而有效地控制水质恶化情况。分析了支持向量机的回归理论和算法;构建了支持向量机水质预测模型。应用实例以通州区新江海河站点为研究对象,取NH3-N浓度和TP浓度为时间序列样本,运用支持向量回归机的理论与方法,构造预测模型,并利用Libsvm软件包和MATLAB软件进行水质预测。从整体预测效果来看,其预测结果能较好地反映水质情况。     

基于主成分分析的支持向量机需水预测模型及其应用

需水预测是水资源优化配置、水资源规划和水资源管理的重要依据,其预测精度受到众多因素的影响,且实际用水量数据时间系列较短,制约了传统预测方法的应用。利用支持向量机在对小样本学习的基础上对其他样本进行快速、准确的拟合预测的特点,采用主成分分析与支持向量机相结合的方法,首先利用主成分分析法筛选需水量的主要影响因子,然后将其作为输入样本,对支持向量机模型进行训练和检验,寻找最优模型,并将该方法应用于洛阳市需水预测。结果表明,该模型预测结果平均相对误差为-0.83%,预测精度较高,可作为训练样本较少情况下的一种需水预测方法。     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

粉质仪和拉伸仪在面粉生产中的应用

在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。     

农村信息化服务的现状及建设措施

分析当前我国农村信息化服务的现状,提出加强农村信息化服务的新举措。     

车辆ABS控制算法的研究及探讨

对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。