基于微区域PM2.5浓度卡尔曼插值预测模型的研究

目前颗粒物(尤其是PM2.5)污染问题日趋严重,人们对其关注度越来越高。本文提出一种结合三次样条插值方法的卡尔曼预测模型并将其应用于微区域校园环境PM2.5浓度的预测,以及实现PM2.5浓度的插值模拟图,模拟PM2.5的空间分布。本文实验基于实验室已搭建的环境信息监测系统服务器数据,其PM2.5浓度数据预测值和实际值通过Wilcoxon带符号秩检验后,双侧渐进显著性概率为0.527,远大于显著性水平α=0.05。同时,与神经网络模型预测方法(BP预测)和支持向量机预测方法(SVM预测)对比,卡尔曼预测模型的结果更理想,其日均值PM2.5浓度数据预测值和监测值的平均绝对误差(MEA)为1.8μg/m3,平均相对误差(MER)为6%,相关系数R为0.87。实验结果表明:卡尔曼预测模型能有效地用于PM2.5浓度预测,结合样条插值方法可以较好地模拟PM2.5的空间分布及局部污染特征。     

A Higher Order Interpolation Scheme of Finite Volume Method for Compressible Flow on Curvilinear Grids

A higher order interpolation scheme based on a multi-stage BVD (Boundary Variation Diminishing) algorithm is developed for the FV (Finite Volume) method on non-uniform, curvilinear structured grids to simulate the compressible turbulent flows. The designed scheme utilizes two types of candidate interpolants including a higher order linear-weight polynomial as high as eleven and a THINC (Tangent of Hyperbola for INterface Capturing) function with the adaptive steepness. We investigate not only the accuracy but also the efficiency of the methodology through the cost efficiency analysis in comparison with well-designed mapped WENO (Weighted Essentially Non-Oscillatory) scheme. Numerical experimentation including benchmark broadband turbulence problem as well as real-life wall-bounded turbulent flows has been carried out to demonstrate the potential implementation of the present higher order interpolation scheme especially in the ILES (Implicit Large Eddy Simulation) of compressible turbulence.     

Parallel magnetic resonance imaging using localized receive arrays with sinc interpolation (PILARS)

Large arrays with localized coil sensitivity make it possible to use parallel imaging to significantly accelerate MR imaging speed. However, the need for auto calibration signals limits the actual acceleration factors achievable with large arrays. This paper presents a novel method for parallel imaging with large arrays. The method uses Sinc kernels for k‐space data interpolation that only requires one phase parameter to be estimated using a small size of calibration signals. Simulations based on synthetic array data and phantom experiments show that the new method can achieve higher actual acceleration factors with comparable reconstruction quality. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

基于边界信息的医学图像三维插值

目的Cubic卷积插值是医学图像三维插值的常用方法,针对其插值处的结果边界模糊和精度不高的缺陷,建立一种精确度较高的插值方法。方法首先通过模糊对比度增强精确定位图像边界,再运用形态学运算确定出新插值图像边界,对于新插值图像边界点采用最佳匹配对应点插值;对于非边界点采用一种新的Cubic卷积插值方法确定其灰度值。结果本文方法的均方差、不符合像素点数和最大误差均小于传统插值方法。结论本文提出的方法具有较高的精确性。     

普通克立格法预测江宁县江滩钉螺分布

目的　探讨江宁县江滩钉螺孳生分布的预测方法。　方法　以变异函数分析江宁县江滩钉螺分布的空间自相关性,并以此为基础用普通克立格法 (OrdinaryKriging)预测江宁县江滩钉螺的分布。　结果　 2000年江宁县江滩钉螺分布呈空间自相关性,其变异函数为球型模型,且当距离小于0.0301时,钉螺空间分布变异与距离有关。进一步以此为基础用普通克立格法建立了江宁县江滩钉螺分布预测图,交叉核验显示预测图是对江滩钉螺分布最优无偏估计,预测模型的决定系数R2=0.973。　结论　普通克立格法能有效利用监测资料预测江宁县江滩钉螺的分布状况。     

Release phenomena of insulin from an implantable device composed of a polyion complex of chitosan and sodium hyaluronate

An implant controlled-release system for protein drug delivery based on a polyion complex device composed of chitosan (CS) and sodium hyaluronate (HA) was investigated. The conditions which generated the greatest amount of the polyion solid complex were studied to ascertain the formation of polyion complex between CS and HA. The greatest amount of the polyion complex was formed at the weight ratio of 3 to 7 (CS:HA) at pH 3.5. Furthermore, the CS–HA pellets were prepared and then drug release from CS–HA pellets was evaluated using insulin as a model drug. The results demonstrated that the insulin release from CS–HA pellets was markedly influenced by both the change in the polymer mixing ratio and the total pellet weight, whereas the compression pressure did not affect the release significantly. An artificial neural network (ANN) and biharmonic spline interpolation (HSI) were employed to predict the actual relation between causal factors and the release rate constant of insulin. Although both the ANN and HSI successfully represented a non-linear relationship between the formulation factors and the release rate constant, HSI methodology gave a better estimation than that of the ANN.     

Central fatigue of the first dorsal interosseous muscle during low-force and high-force sustained submaximal contractions

The aim of this study was to compare the extent of central fatigue in the first dorsal interosseous (FDI) muscle of healthy adults in low, moderate and high-force submaximal contractions. Nine healthy adults completed four experimental sessions where index finger abduction force was recorded during voluntary contractions and in response to brief trains (five pulses at 100 Hz) of electrical stimulation. The ability to maximally activate FDI under volition, or voluntary activation, and its change with sustained activity (central fatigue) was assessed using the twitch interpolation technique. The fatigue tasks consisted of continuous isometric index finger abduction contractions held until exhaustion at four target force levels: 30%, 45%, 60% and 75% of the maximal voluntary contraction. The main finding was the presence of central fatigue for the 30% task, but not for the three other fatigue tasks. The extent of central fatigue was also associated with changes in a measure reflecting the status of peripheral structures/mechanisms. It appears that central fatigue contributed to task failure for the lowest force fatigue task (30%), but not for the other (higher) contraction intensities.     

陈旧性膝关节运动损伤者股四头肌随意动员能力下降

目的:观察陈旧性膝关节运动损伤股四头肌随意动员能力的变化。方法:60名天津体育学院学生,自愿参加测试,根据其是否有陈旧性膝关节运动损伤分为2组,损伤组(有训练史)30人,对照组(无训练史)30人。应用股四头肌随意动员能力评定系统测定分析股四头肌最大随意等长肌力(MVC)、随意动员能力(MA)和力量上升速率(RFD)。结果:对照组两侧股四头肌MVC、MA和RFD无显著差异(P>0.05),损伤组两侧股四头肌MVC无显著性差异(P>0.05)。对照组右侧股四头肌MVC、RFD值显著低于损伤组未损伤侧(P<0.05,P<0.01),损伤组膝关节损伤侧MA、RFD值显著低于未损伤侧(P<0.05,P<0.01)。结论:即使陈旧性膝关节运动损伤者股四头肌肌肉力量已恢复到未损伤侧水平,其随意动员能力和力量上升速率依然较低,膝关节神经肌肉控制仍较差,这可能是影响陈旧性膝关节运动损伤功能状态的主要因素之一。股四头肌随意动员能力评价系统可检测这一变化。