Polynomial matrix solution of H2 optimal control problem for state‐space systems

A polynomial matrix solution to the H₂ output feedback optimal control problems is obtained for systems represented in state‐equation form. The proof does not invoke the separation principle but is obtained in the z‐domain. The cost function includes weighted states, which allows the so‐called standard system model problem to be solved. This encompasses the class of inferential control problems. The results also enable the two‐degree‐of‐freedom optimal control solution properties to be explored. Copyright © 2002 John Wiley & Sons, Ltd.     

An algorithm for the automated quantitation of metabolites in in vitro NMR signals.

The quantitation of metabolite concentrations from in vitro NMR spectra is hampered by the sensitivity of peak positions to experimental conditions. The quantitation methods currently available are generally labor intensive and cannot readily be automated. Here, an algorithm is presented for the automatic time domain analysis of high-resolution NMR spectra. The TARQUIN algorithm uses a set of basis functions obtained by quantum mechanical simulation using predetermined parameters. Each basis function is optimized by subdividing it into a set of signals from magnetically equivalent spins and varying the simulated chemical shifts of each of these groups to match the signal undergoing analysis. A novel approach to the standard multidimensional minimization problem is introduced based on evaluating the fit resulting from different permutations of possible chemical shifts, obtained from one-dimensional searches. Results are presented from the analysis of (1)H proton magic angle spinning spectra of cell lines illustrating the robustness of the method in a typical application. Simulation was used to investigate the biggest peak shifts that can be tolerated.     

The use of 3D surface fitting for robust polyp detection and classification in CT colonography

In this paper we describe the development of a computationally efficient computer-aided detection (CAD) algorithm based on the evaluation of the surface morphology that is employed for the detection of colonic polyps in computed tomography (CT) colonography. Initial polyp candidate voxels were detected using the surface normal intersection values. These candidate voxels were clustered using the normal direction, convexity test, region growing and Gaussian distribution. The local colonic surface was classified as polyp or fold using a feature normalized nearest neighborhood classifier. The main merit of this paper is the methodology applied to select the robust features derived from the colon surface that have a high discriminative power for polyp/fold classification. The devised polyp detection scheme entails a low computational overhead (typically takes 2.20 min per dataset) and shows 100% sensitivity for phantom polyps greater than 5 mm. It also shows 100% sensitivity for real polyps larger than 10 mm and 91.67% sensitivity for polyps between 5 to 10 mm with an average of 4.5 false positives per dataset. The experimental data indicates that the proposed CAD polyp detection scheme outperforms other techniques that identify the polyps using features that sample the colon surface curvature especially when applied to low-dose datasets.     

基于GMDH型神经网络的EEG分类研究

为了提高对不同认知状态下脑电信号(EEG)的分类正确率，提出一种GMDH型神经网络及改进的训练算法。此网络结构在演化中生成，分类规则由简单多项式表示，训练算法可防止出现过拟合。此网络用于区分算术运算和休息状态下的脑电信号，正确率达到84．5％，与标准前向型神经网络(FNN)比较，显示了较好的分类效果。     

停—升—停多项式凸轮曲线族

提出三个多项式凸轮曲线族。使用者可根据不同的用途，用优化方法求得待定系数值，从满足边界条件的曲线族中挑选出一条综合性能最优的凸轮曲线。还提供了待定系数与所选凸轮曲线的诸特性值之间关系的图表。     

云纹技术在断裂分析中的应用

改进了传统的云纹数据处理方法,提出用曲面拟合方法处理云纹数据,提高了计算机处理云纹数据的效率与质量。又提出用云纹法测量J积分的技术,可望解决实际工程构件的J积分测量问题。     

The Validity of the Neale and Kendler Model-Fitting Approach in Examining the Etiology of Comorbidity

Given that knowledge regarding the etiology of comorbidity between disorders can have a significant impact on research regarding the classification, treatment, and etiology of the disorders, the ability to reject incorrect hypotheses regarding the causes of comorbidity is very important. A simulation study was conducted to assess the validity of the Neale and Kendler (1995) model-fitting approach in examining the etiology of comorbidity between two disorders. First, data were simulated under the assumptions of the 13 alternative comorbidity models described by Neale and Kendler. Second, model-fitting analyses testing the comorbidity models were conducted on the simulated datasets. Thirteen sets of data with varying model parameters were simulated to test Neale and Kendler's assertion that their model-fitting approach is appropriate across a range of potential prevalences and degrees of familiality. The validity of the model-fitting approach in examining unselected twin data and a combination of selected family data and unselected family data was explored. The model-fitting approach successfully discriminated several classes of comorbidity models, although discrimination between models within classes of related models was less accurate. Results suggest that the model-fitting approach can be a useful tool in examining the etiology of the comorbidity between disorders if the caveats of the present study's results are considered carefully. As predicted by Neale and Kendler, variations in the disorder prevalences and familial correlations did not affect the validity of their model-fitting approach, but affected the power to discriminate the correct model. As suggested by Neale and Kendler, the model-fitting approach can be applied to both unselected and selected data and to both twin and family data.     

Geometric modeling of the human torso using cubic hermite elements

We discuss the advantages and problems associated with fitting geometric data of the human torso obtained from magnetic resonance imaging, with high-order (bicubic Hermite) surface elements. These elements preserve derivative (C ¹) continuity across element boundaries and permit smooth anatomically accurate surfaces to be obtained with relatively few elements. These elements are fitted to the data with a new nonlinear fitting procedure that minimizes the error in the fit while maintainingC ¹ continuity with nonlinear constraints. Nonlinear Sobelov smoothing is also incorporated into this fitting scheme. The structures fitted along with their corresponding root meansquared error, number of elements used, and number of degrees of freedom (df) per variable are: epicardium (0.91 mm, 40 elements, 142 df), left lung (1.66 mm, 80 elements, 309 df), right lung (1.69 mm, 80 elements, 309 df), skeletal muscle surface (1.67 mm, 264 elements, 1,010 df), fat layer (1.79 mm, 264 elements, 1,010 df), and the skin layer (1.43 mm, 264 elements, 1,010 df). The fitted surfaces are assembled into a combined finite element/boundary element model of the torso in which the exterior surfaces of the heart and lungs are modeled with two-dimensional boundary elements and the layers of the skeletal muscle, fat, and skin are modeled with finite elements. The skeletal muscle and fat layers are modeled with bicubic Hermite linear elements and are obtained by joining the adjacent surface elements for each layer. Applications for the torso model include the forward and inverse problems of electrocardiography, defibrillation studies, radiation dosage studies, and heat transfer studies.     

基于直方图拟合的MRI图像水平集分割

利用混合高斯模型对MRI图像直方图进行分析,将拟合获得的特征参数作为水平集曲线进化的约束条件,对医学图像进行分割。分割中采用的自适应Level Set方法,能够自适应地确定曲线进化方向（扩张或收缩）,而不必在分割之前指定其进化方向,减少了人工干预;同时也克服了传统测地活动轮廓线（GAC）方法对图像梯度信息的过分依赖,以及由于对图像进行大尺度高斯平滑处理造成边缘点移动、定位准确度下降的缺陷。分别对MRI仿真和真实图像进行了实验,MRI仿真实验的分割敏感性、专一性和总体性能指标分别达到了94.72%、97.52%和97.22%。分割结果的定量分析和定性分析表明算法的有效性以及较高的分割准确度。     

MART-1 HLA-A2限制性CTL表位的预测

目的 预测黑色素瘤分化抗原ＭＡＲＴ－１的ＨＬＡ－Ａ２限制性细胞毒性Ｔ淋巴细胞（ＣＴＬ）表位。方法 采用超基序与量化基序多项式方案相结合的办法,对目的抗原ＭＡＲＴ－１的ＨＬＡ－Ａ２限制性ＣＴＬ表位进行预测。结果 预测出了６个九肽表位。结论 两种方法预测结果的一致性较好,所预测出的６个ＭＡＲＴ－１的ＨＬＡ－Ａ２限制性ＣＴＬ表位经后续实验筛选,鉴定后,可望用于新型ＭＡＲＴ－１肿瘤治疗性多肽疫苗的设计研究