七轴五联动螺旋桨加工机床控制系统关键技术

为解决大型螺旋桨加工车铣复合机床的控制问题,提出了基于运动控制器和以太网的开放式数控系统体系结构,其上位机采用通用的工业计算机,下位机采用高性能运动控制器.进而提出了基于坐标映射的插补算法,通过将真实的3旋转2直线坐标系和虚拟的3直线2旋转的标准坐标系的双向映射和通用的插补算法的集成,完成了4旋转2直线的特殊机床结构的插补算法;采用双电机同步耦合驱动技术,消除大型回转工作台传动间隙,确保工作台精确跟踪插补结果,控制两台电机分别驱动工作台的两个方向运动,同时通过其产生的反向张力使得两台电机的传动链按照规定方向绷紧,可以有效地消除机械间隙.     

基于一阶振型斜率的剪切型建筑结构损伤定位

提出了一种利用结构一阶振型斜率改变判断剪切型结构损伤位置的方法.首先,进行结构振型和振型斜率对损伤的敏感性分析,导出敏感性系数表达式.然后,计算结构损伤前后的一阶振型斜率差.最后,在敏感性分析和计算得到的结构一阶振型斜率差的基础上,通过迭代计算消除多损伤引起的振型斜率改变叠加进行损伤定位.通过10层剪切型框架结构不同损伤工况的数值分析表明,所提出的算法能够正确识别所有的损伤位置.     

分支结构血管中血液的对流换热分析

用有限元方法数值模拟了血管分支结构内血液流动的三维速度场和温度场,得到了分支血管壁面3个典型径向角度的局部努塞尔数和血管截面平均努塞尔数沿管长的变化曲线.结果表明:分支血管入口处的速度场和温度场分布与单管的分布明显不同;不同径向角度的局部努塞尔数相差很大;分支血管入口处截面平均努塞尔数大于单个直管内截面平均努塞尔数,且出现一个极大值Numax.计算了不同分支角度和分支半径比时的截面平均努塞尔数,结果表明:分支角度和半径比对Numax的大小和位置有一定影响;半径比越小,分支血管内截面平均努塞尔数趋于稳定值的速度越快.     

An Adaptive Multiscale Ensemble Learning Paradigm for Nonstationary and Nonlinear Energy Price Time Series Forecasting

For forecasting nonstationary and nonlinear energy prices time series, a novel adaptive multiscale ensemble learning paradigm incorporating ensemble empirical mode decomposition (EEMD), particle swarm optimization (PSO) and least square support vector machines (LSSVM) with kernel function prototype is developed. Firstly, the extrema symmetry expansion EEMD, which can effectively restrain the mode mixing and end effects, is used to decompose the energy price into simple modes. Secondly, by using the fine‐to‐coarse reconstruction algorithm, the high‐frequency, low‐frequency and trend components are identified. Furthermore, autoregressive integrated moving average is applicable to predicting the high‐frequency components. LSSVM is suitable for forecasting the low‐frequency and trend components. At the same time, a universal kernel function prototype is introduced for making up the drawbacks of single kernel function, which can adaptively select the optimal kernel function type and model parameters according to the specific data using the PSO algorithm. Finally, the prediction results of all the components are aggregated into the forecasting values of energy price time series. The empirical results show that, compared with the popular prediction methods, the proposed method can significantly improve the prediction accuracy of energy prices, with high accuracy both in the level and directional predictions. Copyright © 2016 John Wiley & Sons, Ltd.     

Mutations in myosin heavy chain 11 cause a syndrome associating thoracic aortic aneurysm/aortic dissection and patent ductus arteriosus

We have recently described two kindreds presenting thoracic aortic aneurysm and/or aortic dissection (TAAD) and patent ductus arteriosus (PDA) and mapped the disease locus to 16p12.2-p13.13 (ref. 3). We now demonstrate that the disease is caused by mutations in the MYH11 gene affecting the C-terminal coiled-coil region of the smooth muscle myosin heavy chain, a specific contractile protein of smooth muscle cells (SMC). All individuals bearing the heterozygous mutations, even if asymptomatic, showed marked aortic stiffness. Examination of pathological aortas showed large areas of medial degeneration with very low SMC content. Abnormal immunological recognition of SM-MHC and the colocalization of wild-type and mutant rod proteins in SMC, in conjunction with differences in their coimmunoprecipitation capacities, strongly suggest a dominant-negative effect. Human MYH11 gene mutations provide the first example of a direct change in a specific SMC protein leading to an inherited arterial disease.     

Control of a key transition from prostrate to erect growth in rice domestication

The transition from the prostrate growth of ancestral wild rice (O. rufipogon Griff.) to the erect growth of Oryza sativa cultivars was one of the most critical events in rice domestication. This evolutionary step importantly improved plant architecture and increased grain yield. Here we find that prostrate growth of wild rice from Yuanjiang County in China is controlled by a semi-dominant gene, PROG1 (PROSTRATE GROWTH 1), on chromosome 7 that encodes a single Cys(2)-His(2) zinc-finger protein. prog1 variants identified in O. sativa disrupt the prog1 function and inactivate prog1 expression, leading to erect growth, greater grain number and higher grain yield in cultivated rice. Sequence comparison shows that 182 varieties of cultivated rice, including 87 indica and 95 japonica cultivars from 17 countries, carry identical mutations in the prog1 coding region that may have become fixed during rice domestication.     

Meta-analysis of genome-wide association data and large-scale replication identifies additional susceptibility loci for type 2 diabetes

Genome-wide association (GWA) studies have identified multiple loci at which common variants modestly but reproducibly influence risk of type 2 diabetes (T2D). Established associations to common and rare variants explain only a small proportion of the heritability of T2D. As previously published analyses had limited power to identify variants with modest effects, we carried out meta-analysis of three T2D GWA scans comprising 10,128 individuals of European descent and approximately 2.2 million SNPs (directly genotyped and imputed), followed by replication testing in an independent sample with an effective sample size of up to 53,975. We detected at least six previously unknown loci with robust evidence for association, including the JAZF1 (P = 5.0 x 10(-14)), CDC123-CAMK1D (P = 1.2 x 10(-10)), TSPAN8-LGR5 (P = 1.1 x 10(-9)), THADA (P = 1.1 x 10(-9)), ADAMTS9 (P = 1.2 x 10(-8)) and NOTCH2 (P = 4.1 x 10(-8)) gene regions. Our results illustrate the value of large discovery and follow-up samples for gaining further insights into the inherited basis of T2D.     

综合环境费用的概念与计算方法研究

在分析了环境费用的概念及估价方法后 ,针对环境费用较难以估量的问题 ,提出了综合环境费用的概念 ,并在投入占用产出的框架内 ,给出了三种计算方法 .在综合环境费用的基础上 ,给出了衡量环境破坏程度的相对指标 -环境破坏度的概念 ,并对其计算方法进行了研究 .     

县域土地利用变化分析

以温州市永嘉县1990－1996年土地利用为研究内容,计算了有关土地利用的多种静态和动态指标,提出了新的土地利用动态量度的指标－结构转换度,并研究了各类土地利用及其变动人口密度、经济发展之间的关系。