Visualization of Nonlinear Phenomena with FreeFem++ and Paraview : Application to Reaction-Diffusion System and Fluid Dynamics

様々な自然現象は非線形偏微分方程式により数理モデル化される。現時点では非線形偏微分方程式に対する万能な方法はない。従って, 数値計算は非線形偏微分方程式の解の様相を理解する手段として有効な方法の一つである。本稿では, 有限要素法による数値解析の為のオープンソフトウェアFreeFem++ を用いた非線形偏微分方程式の数値計算と可視化ソフトウェアParaview を用いた数値解の可視化について述べる

李群在数值求解偏微分方程中的新应用

随着计算机技术的提高及数值计算方法的不断完善，数值计算逐渐成为研究海洋工程领域内水波动力学的有效手段，以前难以处理的非线性现象研究课题在数值手段的帮助下也出现了求解的可能。本文所研究的李群理论在非线性偏微分方程数值求解中的应用，便是这些手段中的一种。本文的选题背景为纯粹数学理论的应用与研究，通过对非线性力学方程求解方法研究现状的分析，结合李群在偏微分方程中的应用理论，提出一种偏微分方程的降维方法：从无穷小变换出发，构建保持偏微分方程不变性的李群，导出偏微分方程的降维系统，结合非经典方法中的解曲面条件，避开群不变量解的直接求解，同时实现偏微分方程的降维简化，得出原偏微分方程的数值描述。在此基础上，本文在应用实例中通过与某些偏微分方程已知精确解的比较，结果验证了该方法的合理性及有效性。在利用该方法求解几个典型的非线性水波动力学偏微分方程时，得出了一系列关于这些方程的新的数值解，并由此揭示了一些有意义的水波物理现象。 本文研究工作的意义在于丰富了偏微分方程的数值解法，为利用数值方法处理非线性问题提供了新思路，通过对水波动力学方程的求解，为海洋潮流、波浪能的基础研究做出了必要的理论铺垫，对海洋工程的实际应用也具有一定的参考价值

Broadband Measurements of Ultrasonic Waves Using Optical Beam Deflection

超音波による光偏向現象を利用した広帯域超音波計測を、流体の非線形性パラメータの測定とゼラチンゲル中の広帯域吸収測定に応用した。音波長に比べて細いレーザビームを波面に平行に伝搬させると、レーザは偏向し、その偏向角から音圧の時間微分に比例した信号が得られる。この検出法の広帯域特性を生かして、2種類の実験を行った。波形ひずみから水、エタノールの非線形性パラメータを求めた。さらに広帯域音波パルスの伝搬距離依存性からゼラチンゾル・ゲル中の吸収を5-35MHzで測定することができた

大学トレーニングセンターにおけるトレーニング器具の衛生状況について

University training center users include those attempting to improve their health. There are reports of a tendency of annual increase in the number of elderly people visiting fitness clubs. Thus, fitness clubs are now facilities receiving increasing demands and users. Under such circumstances, measures for preventing infections seem to be necessary in fitness clubs. However, till date, few reports have been published concerning hygienic management at fitness clubs. The present study was undertaken to investigate the hygienic status of machines used at fitness clubs. The number of bacteria present on 7 areas on dumbbells was measured thrice during the study and the bacterial count varied each day. In addition, the numbers of general bacteria and drug-resistant bacteria present on the machines that came in contact with users’ hands were investigated, revealing a large number of general bacteria and drug-resistant bacteria present on these machines. The finding of large counts of bacteria on the training machines despite some daily variations indicates the necessity for hygienic control on fitness club training machines

Social Media, Big Data, Investor Sentiment and Stock Return Prediction

近些年来，Web2.0技术臻于成熟。随着互联网技术的飞速发展和移动电子设备的不断普及，各类形式的社交媒体不断涌现出来，并得到了广泛的应用。庞大的社交媒体用户群体每天在各类平台上表达自己的观点、见解、心情，这些信息都被自动记录下来，被称作用户生成数据（UserGeneratedData）。社交媒体上天然的海量数据为学术研究提供了良好的数据来源。社交媒体大数据被尝试应用于各个领域。本文从中文社交媒体大数据出发，以投资者情绪为桥梁，系统性分析社交媒体大数据对金融市场的预测作用以及大数据本身的偏差性问题。本文在对已有的相关研究和理论进行综述后，对我国社交媒体的发展现状进行了分析，在此基础上重点进行了如...Benefit both from the rapidly developing of the technology of Web2.0 and the wide spread use of mobile device, many kinds of social media platforms, like Twitter and Facebook, are emerging during the past couples of years. Those social media platforms attracted billions of users worldwide. Huge amount of users are posting their views, opinions, emotions etc. on social media every single day. All o...学位：博士后院系专业：管理学院_财务学学号：201317004

New NDT method for ferromagnetic materials based on differential permeability

利用微分磁导率变化特性,提出了一种可对材料的宏观缺陷进行快速扫查的无损检测新方法。首先,将铁磁性材料置于偏置磁化场环境下,缺陷将导致内部磁通的畸; 变;其次,磁通畸变进一步体现在材料表面微分磁导率分布的差异性;再次,通过特殊设计的微分磁导率检测探头,对材料表面微分磁导率的分布进行扫查;最后,; 由磁导率分布差异获得材料内部的不连续性信息,从而实现对缺陷的无损检测。开展了系列验证实验,结果表明,相对于传统的漏磁检测方法,新方法具有磁化强度; 低、磁通泄漏少、检测信号稳定的特点。新方法正、反面缺陷探测信号存在差异,在缺陷深度识别方面亦存在优势。A new non-destructive testing method is proposed to fast scan and detect; the macroscopic defects of materials using the variation characteristics; of the differential permeability of ferromagnetic materials. Firstly,the; ferromagnetic material,such as steel plate,is placed under the bias; magnetic field,and the defects in the material will inevitably lead to; the distortion of its internal magnetic flux. Secondly,the magnetic flux; distortion is further reflected in the difference of the differential; permeability distribution on the surface of the tested material.; Thirdly,using a specially designed probe,the distribution of; differential permeability on the surface of tested material is rapidly; scanned. Finally,from the difference of the differential permeability; distribution,the discontinuity information in the material can be; obtained,so as to realize the nondestructive testing of macroscopic; defects. Series of experiments were carried out,and the results show; that,compared with traditional magnetic flux leakage method,the new; method has the advantages of low magnetic intensity,less flux leakage; and stable detection signals. Moreover,the detection signals for the; front-side and back-side defects have obviously different distribution; characteristics,and the method also has obvious advantages in the field; of defect depth identification.国家自然科学基金; 福建省科技计划重大专

Various properties relative to intermittency of space-time fractional SPDEs

研究種目：基盤研究(C)研究期間：2016～2019課題番号：16K05197研究代表者：謝　賓研究者番号：50510038Other2016～2019年度科学研究費助成事業（基盤研究(C)）研究成果報告書　課題番号：16K05197　研究代表者：謝　賓research repor