关键词： Scheduling   Hybrid flow shop   Assembly   Heuristic   Two-stage production system  

摘要： In this paper, a scheduling problem for a two-stage production system including machining operations and assembly operations is studied. In this system, a number of products of different kinds are produced. Each product is assembled with a set of several parts. The first stage is a hybrid flow shop to produce parts. All machines can process all kinds of parts in this stage, but each machine can process only one part at a time. The second stage is a single assembly machine or a single assembly team of workers. The considered objective is to minimize the completion time of all products (makespan). A mathematical modeling is presented, and since this problem has been proved strongly nondeterministic polynomial-time hard, a series of heuristic algorithms based on the basic idea of Johnson algorithm is proposed. Also, two lower bounds is introduced and improved to evaluate the final solution obtained from heuristic algorithms. The numerical experiments are used to evaluate the performance of the proposed algorithms.

关键词： CBCT   Iterative algebraic algorithms   Convergence   Image quality  

摘要： Cone beam computed tomography (CBCT) enables a volumetric image reconstruction from a set of 2D projection data. It plays an important role in image guided radiation therapy (IGRT). However, it is desirable to lower the patient radiation dose while maintaining good quality tomographic reconstructions. Hence, methods are needed even when the data is undersampled or there are limited projections. Iterative algorithms such as ART, SART and OS-SART are known to perform well under such circumstances. The performance of ART, SART and OS-SART is here studied based on a range of norm measurements (RMS reconstruction error, RMS projection error, and the L1 norm and L2 norm of the image error). Image quality measurements for uniformity and noise are also introduced. Since image quality often degrades as iterative algorithms converge, a simple function is used to trade off convergence with image quality. Investigations are performed using simulated and experimental data. (c) 2012 Elsevier Ireland Ltd. All rights reserved.

关键词： voxel-based morphometry   VBM   DARTEL   hypothyroidism  

摘要： The present study aimed to investigate whether brain morphological differences exist between adult hypothyroid subjects and age-matched controls using voxel-based morphometry (VBM) with diffeomorphic anatomic registration via an exponentiated lie algebra algorithm (DARTEL) approach. High-resolution structural magnetic resonance images were taken in ten healthy controls and ten hypothyroid subjects. The analysis was conducted using statistical parametric mapping. The VBM study revealed a reduction in grey matter volume in the left postcentral gyrus and cerebellum of hypothyroid subjects compared to controls. A significant reduction in white matter volume was also found in the cerebellum, right inferior and middle frontal gyrus, right precentral gyrus, right inferior occipital gyrus and right temporal gyrus of hypothyroid patients compared to healthy controls. Moreover, no meaningful cluster for greater grey or white matter volume was obtained in hypothyroid subjects compared to controls. Our study is the first VBM study of hypothyroidism in an adult population and suggests that, compared to controls, this disorder is associated with differences in brain morphology in areas corresponding to known functional deficits in attention, language, motor speed, visuospatial processing and memory in hypothyroidism.

关键词： “算法多样化”   小学数学   个性化学习   课程理念   思维能力   教育目的   创新意识   数学素养  

摘要： 新课程理念提倡个性化学习，张扬学生的个性，提倡“算法多样化”，这固然是鼓励个性化学习，但是数学的教育目的除了发展学生的思维能力，培养学生的创新意识，提高学生的数学素养外，还要让学生掌握高效统一的运算方法和熟练的技能。因此，在课堂教学中不能只为体现新理念而盲目追求“算法多样化”。

关键词： 边缘检测   小波变换   形态学梯度运算   小波降噪   融合技术  

摘要： 针对传统的基于小波变换的边缘检测法无法提取低频区域完整连续的边缘,并且会丢弃包含一些重要细节的高频区域,同时受到噪声的影响而导致边缘提取效果不佳的问题,提出了一种基于融合技术的小波变换和数学形态学的边缘检测算法.在小波域中,对低频子图像采用数学形态学进行边缘检测,对高频子图像先进行小波降噪再采用小波模极大值法进行加权边缘检测,最后采用一定的融合规则对高、低频边缘子图像进行融合.实验结果表明,该方法用于图像边缘提取,不但能有效去除噪声干扰,又能突出边缘细节,边缘定位连续准确.

关键词： 高中数学   算法初步   比较   教学建议  

摘要： 通过对人教A、B版数学3的"算法初步"的内容进行比较探讨,以"算法初步"的教研内容为学习对象,具体例题具体分析,对教课书上的章节、组织结构和习题等多方面的内容进行详细的比较研究。

关键词： Nonconvex nonsmooth optimization   Semi-algebraic optimization   Tame optimization   Kurdyka-Lojasiewicz inequality   Descent methods   Relative error   Sufficient decrease   Forward-backward splitting   Alternating minimization   Proximal algorithms   Iterative thresholding   Block-coordinate methods   o-minimal structures  

摘要： In view of the minimization of a nonsmooth nonconvex function f, we prove an abstract convergence result for descent methods satisfying a sufficient-decrease assumption, and allowing a relative error tolerance. Our result guarantees the convergence of bounded sequences, under the assumption that the function f satisfies the Kurdyka-Aojasiewicz inequality. This assumption allows to cover a wide range of problems, including nonsmooth semi-algebraic (or more generally tame) minimization. The specialization of our result to different kinds of structured problems provides several new convergence results for inexact versions of the gradient method, the proximal method, the forward-backward splitting algorithm, the gradient projection and some proximal regularization of the Gauss-Seidel method in a nonconvex setting. Our results are illustrated through feasibility problems, or iterative thresholding procedures for compressive sensing.

关键词： Evolutionary algorithms   Multi-objective optimization   Global optima   Cluster analysis   Parameter identification   Genetic regulation  

摘要： Based on evolutionary computation techniques, we present a parallel, globally convergent, multi-objective optimization algorithm which extends the Covariance Matrix Adaptation Evolutionary Strategy (CMA-ES). This approach enables identifying multiple global optima and multiple discontinuous Pareto set solutions of the optimization problem in a compact search space. After evaluating the algorithm with test functions, we apply our method to the identification of the parameters of a reaction-diffusion model of a genetic regulatory mechanism during Drosophila early development, our simulations being in agreement with the experimental data. Comparisons with a multi-objective version of the CMA-ES (MO-CMA-ES) on this dataset show that our algorithm outperforms largely the speed of convergence of MO-CMA-ES. We have identified an infinite number of accurate solutions of the model equations, associated with the Pareto set of the optimization problem. This non-unicity property of a biological developmental process explains phenotypic plasticity and resilience in biological systems. (C) 2012 Elsevier B.V. All rights reserved.