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关键词： computational geometry   computer-aided design   design automation   design for manufacturing   design optimization   topology optimization   Laplacian smoothing  

摘要： The potential of additive layer manufacturing (ALM) is high, with a whole new set of manufacturable parts with unseen complexity being offered. Moreover, the combination of topology optimization (TO) with ALM has brought mutual advantages. However, the transition between TO and ALM is a nontrivial step that requires a robust methodology. Thus, the purpose of this work is to evaluate the capabilities of adopting the commonly used Laplacian smoothing methodology as the bridging tool between TO and ALM. Several algorithms are presented and compared in terms of efficiency and performance. Most importantly, a different concept of Laplacian smoothing is presented as well as a set of metrics to evaluate the performance of the algorithms, with the advantages and disadvantages of each algorithm being discussed. In the end, the proposed mutable diffusion Laplacian algorithm is presented and exhibits less volume shrinkage and shows better preservation of some geometrical features such as thin members and edges. Moreover, a new volume constraint is presented, decreasing the resulting structural changes in the presented geometry and improving the final mesh quality.

关键词： 小波包分解   共空间模式方法   脑电运动想象   去噪   决策树   分类方法  

摘要： 针对脑电运动想象信号分类不准确,本研究结合小波包分解和共空间模式,提出了一种脑电运动想象分类方法。采用电极无创式采集脑电运动信号,并利用独立成分分析去噪,通过小波变换和共空间模式,提取脑电运动信号的时域特征和空间域特征。以决策树算法为基础,一个决策树对应一种脑电运动信号类别,构建随机森林分类器,实现脑电运动想象分类。结果表明:与其他分类方法相比,该方法能够较好地控制智能小车的运动反应,证明本研究方法的分类质量更高。

关键词： 有机自旋电子学   有机铁磁体   自旋输运   极化子   动力学  

摘要： 有机铁磁体结合了铁磁体磁特性和有机材料软特性,在有机自旋电子学领域新型材料及器件设计方面具有广阔的应用前景.本文介绍了有机铁磁器件自旋输运方面的研究进展,讨论了基于有机铁磁的自旋过滤、多态磁电阻和自旋整流等新奇概念,阐明了有机铁磁体自身相互作用,如电子-晶格耦合和侧基自旋关联在以上现象中所扮演的角色.同时,对有机铁磁中的极化子特性及微观动力学过程进行了探究.这为未来设计新型有机铁磁器件提供了理论指导.

关键词： 过渡金属配合物   量子信息处理   中心金属离子   低自旋   慢磁弛豫   基态自旋   量子相干   弛豫行为  

摘要： 随着单离子磁体的蓬勃发展,研究人员发现即使当配合物的基态自旋为低自旋(S = 1/2),仍可以表现慢磁弛豫行为。这类配合物在量子信息处理方面(QIP)方面具有较大的应用潜能,因此得到了众多研究者的关注。对于过渡金属配合物,配体的选择影响中心金属离子的电子结构,进而影响其慢磁弛豫行为及量子相干性质。本文结合近年来的研究成果,对低自旋配合物的慢磁弛豫行为进行了阐述,分析了其弛豫行为来源,并对弛豫机理进行总结,为量子比特的设计提供思路。

关键词： 表象训练   射击   业余训练   青少年运动员  

摘要： 运用文献资料法、实验法和数理统计法,探究表象训练对射击业余训练的作用。结果表明,表象训练能显著提高业余射击运动员的技战术水平和稳定性,射击训练和比赛中进行表象训练很有必要。提出射击项目表象训练的重点:培养运动员的抗干扰能力;遵循射击项目特点,规范动作模式;注重表象训练的计划性、规范性和科学性。

关键词： 引领作用   现状和未来   基础科学   造福人类   人类文明   科学成果   核心技术   表象  

摘要： 当前,中国在诸多核心技术领域被卡了脖子。但这只是表象,问题的实质是我们的基础科学大幅落后于美西方。从根本上推动人类文明发展的是科学,还是技术?技术的重要性毋庸置疑。首先,科学成果是通过技术发明来造福人类的;其次,技术进步又能极大地促进科学发现。然而,真正决定人类精神和物质世界的历史、现状和未来的是科学,而不是技术,科学对于技术的支撑和引领作用无以替代。在举国关注“卡脖子”问题的当下,搞清楚这个问题至关重要。

关键词： 量子力学  

ISBN: (纸本)9787572702501

摘要： 本书作者用3幕故事带领我们走进量子力学的世界, 了解那些自量子力学诞生以来就一直困扰着人们的概念问题和严重分歧。第一幕讲述我们在探究量子力学发展轨迹时所需的基本的量子力学概念。第二幕带我们追溯了从20世纪50年代开始的现实主义量子力学方法的复兴, 并且阐述它们的优缺点。第三幕介绍包括作者自己在内的当代物理学家为构建现实主义的万物理论所付出的努力。

关键词： 量子力学  

ISBN: (纸本)9787312053238

摘要： 全书共分为量子世界存在自由意志吗、心智与物质、物理与形而上学: 对量子力学中意识状态的讨论、经典与量子之间的桥梁、量子为何与心智相遇、自旋量子、非虚幻自由意志的量子模型、心智的玻姆哲学等。

关键词： Manifold regularization   Semi-supervised learning   Classification   Vector projection  

摘要： Semi-supervised learning is a new challenge that exploits the information of unlabeled instances. In this paper, we propose a novel Laplacian pair-weight vector projection (LapPVP) algorithm for semi-supervised classification. LapPVP consists of two stages: projection and classification. In the projection stage, LapPVP integrates a within-class scatter, a between-class scatter and a Laplacian regularization together and formulates a pair of optimization problems. The goal of LapPVP is to maximize the between-class scatter and minimize the within-class scatter on the basis of labeled data, and simultaneously maintain the geometric structure of labeled and unlabeled data in the projected subspace. The optimization problems of LapPVP are identical to generalized eigenvalue ones. Thus, it is easy to obtain the optimal solutions to LapPVP. In the classification stage, LapPVP adopts a minimal distance classifier to implement tasks in the projected subspace. The proposed LapPVP can find a better separability using the geometric information embedded in labeled and unlabeled instances and the discriminative information embedded in labeled instance. Experiments on artificial datasets and UCI datasets validate the feasibility and effectiveness of the proposed algorithm. (c) 2021 Elsevier Inc. All rights reserved.

关键词： molecular docking   molecular dynamics simulations   quantum mechanical calculations   estrogen receptor   dynamic binding pattern  

摘要： Estrogen receptor alpha (ER alpha) is a ligand-dependent transcriptional factor in the nuclear receptor superfamily. Many structures of ER alpha bound with agonists and antagonists have been determined. However, the dynamic binding patterns of agonists and antagonists in the binding site of ER alpha remains unclear. Therefore, we performed molecular docking, molecular dynamics (MD) simulations, and quantum mechanical calculations to elucidate agonist and antagonist dynamic binding patterns in ER alpha. 17 beta-estradiol (E2) and 4-hydroxytamoxifen (OHT) were docked in the ligand binding pockets of the agonist and antagonist bound ER alpha. The best complex conformations from molecular docking were subjected to 100 nanosecond MD simulations. Hierarchical clustering was conducted to group the structures in the trajectory from MD simulations. The representative structure from each cluster was selected to calculate the binding interaction energy value for elucidation of the dynamic binding patterns of agonists and antagonists in the binding site of ER alpha. The binding interaction energy analysis revealed that OHT binds ER alpha more tightly in the antagonist conformer, while E2 prefers the agonist conformer. The results may help identify ER alpha antagonists as drug candidates and facilitate risk assessment of chemicals through ER-mediated responses.