Flexible Distribution-Based Regression Models for Count Data: Application to Medical Diagnosis

Abstract

Data mining techniques have been successfully utilized in different applications of significant fields, including medical research. With the wealth of data available within the health-care systems, there is a lack of practical analysis tools to discover hidden relationships and trends in data. The complexity of medical data that is unfavorable for most models is a considerable challenge in prediction. The ability of a model to perform accurately and efficiently in disease diagnosis is extremely significant. Thus, the model must be selected to fit the data better, such that the learning from previous data is most efficient, and the diagnosis of the disease is highly accurate. This work is motivated by the limited number of regression analysis tools for multivariate counts in the literature. We propose two regression models for count data based on flexible distributions, namely, the multinomial Beta-Liouville and multinomial scaled Dirichlet, and evaluated the proposed models in the problem of disease diagnosis. The performance is evaluated based on the accuracy of the prediction which depends on the nature and complexity of the dataset. Our results show the efficiency of the two proposed regression models where the prediction performance of both models is competitive to other previously used regression models for count data and to the best results in the literature.     

小型中间下料预焙电解槽技术条件摆布的思考

对小型中间下料预焙电解槽技术条件摆布的原则和具体数据进行了探讨，提出了尽可能利用从大型预焙槽上得出的先进经验，并消化吸收，掌握好各种条件的平衡，以取得好经济技术指标的观点。     

结构化道路车道线的鲁棒检测与跟踪

针对智能车在视觉导航过程中车道线检测的鲁棒性和实时性问题,提出一种适用于结构化道路的车道线鲁棒检测与跟踪方法。首先,简化的Sobel算子提取车道线边缘图像,将边缘图像与改进的Otsu方法得到的车道线分割图像进行融合,实现对车道线标记点的鲁棒检测;然后,采用迭代最小二乘方法拟合车道线标记点并去除干扰点,并根据拟合参数建立车道线模型;最后,引入尺度无迹卡尔曼滤波(SUKF)对车道线进行跟踪。通过对多段实地采集的视频进行了仿真实验,结果表明,该方法对于高速公路车道线的检测率可达到99%,并具有较好实时性能;对于受损和弄污的城市道路车道线也体现出较好的鲁棒性和时间性能。     

任意裂纹面荷载作用下界面断裂分析

为研究裂纹面上作用的荷载对裂纹稳定性的影响,本文基于比例边界有限元方法提出裂纹面作用有任意方向、任意大小面荷载的界面应力强度因子求解模型.界面裂纹具有复数形式的应力奇异性指数,在任意裂纹面荷载作用下其奇异应力场更为复杂.应用本模型,径向的位移和应力可解析求解,无需网格细分即可自动反映裂尖的应力奇异性.裂纹面上的任意荷载首先可分解成平行于裂纹面以及垂直于裂纹面的分量,并进一步分解成有限项幂函数的和.对每个幂函数荷载解析求解,基于线性叠加原理获得结构在全部荷载作用下的解.该模型对各向同性材料和各向异性材料均适用.文中通过板承受裂缝面荷载时的应力强度因子求解的多个算例对该模型进行了验证和应用,对板的几何尺寸和双材料参数进行了敏感性分析,并应用于重力坝坝踵界面裂缝在水压力作用下的应力强度因子求解.     

库水-重力坝-无限地基系统地震响应分析

为了分析库水以及无限地基辐射阻尼对库水-重力坝-无限地基系统的地震响应影响,通过比例边界有限元法、有限元法以及无限单元法计算了库水-重力坝-无限地基系统的响应.基于SBFEM计算上游坝面库水压力,利用无限单元法分析无限地基辐射阻尼的影响,以Koyna重力坝为研究对象,给出了重力坝在不同地基弹性模量条件下地震位移时程以及应力的响应,随着地基弹性模量的增加,坝体响应增加.与无质量地基模型的计算结果进行对比,考虑无限地基辐射阻尼的计算结果较小.     

Probabilistic crack trajectory analysis by a dimension reduction method

This paper proposes a novel analysis method of stochastic crack trajectory based on a dimension reduction approach. The developed method allows efficiently estimating the statistical moments, probability density function and cumulative distribution function of the crack trajectory for cracked elastic structures considering the randomness of the loads, material properties and crack geometries. First, the traditional dimension reduction method is extended to calculate the first four moments of the crack trajectory, in which the responses are eigenvectors rather than scalars. Then the probability density function and cumulative distribution function of the crack trajectory can be obtained using the maximum entropy principle constrained by the calculated moments. Finally, the simulation of the crack propagation paths is realized by using the scaled boundary finite element method. The proposed method is well validated by four numerical examples performed on varied cracked structures. It is demonstrated that this method outperforms the Monte Carlo simulation in terms of computational efficiency, and in the meanwhile, it has an acceptable computational accuracy.     

Robust admissibility and admissibilisation of uncertain discrete singular time-delay systems

This paper is concerned with the characterisation of robust admissibility and admissibilisation for uncertain discrete-time singular system with interval time-varying delay. Considering the norm-bounded uncertainty and the interval time-varying delay, a new comparison model is introduced to transform the original singular system into two connected subsystems. After this transformation, a singular system without uncertainty and delay can be handled by the Lyapunov–Krasovskii functional method. By virtue of the scaled small gain theorem, an admissibility condition of the original singular system is proposed in terms of linear matrix inequalities. Moreover, the problem of robust admissibilisation of uncertain discrete singular time-varying system is also studied by iterative linear matrix inequality algorithm with initial condition optimisation. Several numerical examples are used to illustrate that the results are less conservative than existing ones.     

波浪对双层圆弧型贯底式开孔介质防波堤的绕射

为研究波浪对双层圆弧型贯底式开孔介质防波堤的绕射问题,利用比例边界有限元方法(SBFEM)建立该问题的半解析解模型.分析时将双层圆弧延伸构建出2个虚拟同心圆可将整个流场可划分成2个有限域和1个无限域.利用变分原理推导出了关于势函数的各个子域SBFEM方程,并对SBFEM方程进行了求解.数值算例验证了该方法是一种只需离散最外边界而且用很少单元便能得到精确结果的高效算法.给出了短峰波波向、相对波数、内外半径比、圆弧段的位置、张角以及孔隙影响系数等因素对整个结构波浪绕射的影响.结果表明,双层圆弧型贯底式开孔介质防波堤与以上参数的变化密切相关.     

快速场(FFP)算法反演海底参数研究

针对弹性海底条件下的声传播问题和海底参数反演问题,在Pekeris海洋声场模型的基础上推导了基于快速场(FFP)理论的两层弹性海底声场计算公式,讨论了其传播规律并利用KrakenC进行了验证.其次结合水池条件,采用能够模拟弹性海底海洋环境的声场测量平台进行缩比实验.反演中,采用了实际测得的传播损失与FFP理论计算值相等的代价函数,讨论了其对各海底参数的敏感度,并选用遗传算法对该代价函数进行寻优计算.反演得到的声传播损失与实验中实际测量结果吻合较好,表明所建立的理论模型符合实际声场环境.