1,148 research outputs found
A computer assisted proof for the Orr-Sommerfeld problem (Feasibility of Theoretical Arguments of Mathematical Analysis on Computer)
No full textNumerical verification methods and computer-assisted proofs for partial differential equations
No full textRecently, various mathematical problems have been solved by computer-assisted proofs, among them the Kepler conjecture, the existence of chaos, the existence of the Lorenz attractor, the famous four-color problem, and more. In many cases, computer-assisted proofs have the remarkable advantage (compared with a “theoretical” proof) of providing accurate quantitative information. The authors have been working more than a quarter century to establish the verified computations of solutions for partial differential equations, mainly to the nonlinear elliptic problems of the form -∆u=f(x,u,∇u) with Dirichlet boundary conditions. Here, by "verified computation" is meant a computer-assisted numerical approach to proving the existence of a solution in a close and explicit neighborhood of an approximate solution. Therefore, the quantitative information by the technique shown here should also be significant from the viewpoint of the a posteriori error estimates for approximate solution of concerned partial differential equations with mathematically rigorous sense. In this monograph, the authors describe a survey on the verified computations or computer-assisted proofs for partial differential equations that they developed. In Part I, the methods mainly studied by authors Nakao and Watanabe are presented. These methods are based on the finite dimensional projection and the constructive a priori error estimates for the finite element approximation of the Poisson equation. In Part II, the computer-assisted approaches via eigenvalue bounds developed by the second author, Plum, are explained in detail. The main task of this method consists of eigenvalue bounds for the corresponding nonlinear problems of the linearized operators. Some brief remarks are also given on other approaches in Part III. Each method in Parts I and II is followed by appropriate numerical examples that confirm the actual usefulness of the authors’ methods. Also in some examples the practical computer algorithms are supplied so that readers can easily implement the verification program by themselves
How ICTs Raise Manufacturing Performance: Firm-level Evidence in Southeast Asia.
No full textThis paper examines the effects of information and communication technologies (ICTs) on business performance, using firm-level data obtained through a questionnaire survey in four ASEAN countries (Indonesia, The Philippines, Thailand and Vietnam). Sources of information and new technologies exchanged via ICTs by firms are also explored to investigate the mechanism behind ICT adoption. Empirical results verify that the introduction of ICT to reorganize business processes is significantly correlated with business performance, in particular the development of export markets and improvement of production management. ICTs facilitate access to information and technologies accumulated in in-house departments and joint-venture (JV) affiliates of the respondent firms. There are considerable differences between multinational companies (MNCs)/JVs and local firms. MNCs/JVs make use of information and technologies obtainable via ICTs from their own R&D departments, JVs established with local partners and foreign-owned suppliers/customers to improve factory management, mostly for product quality improvement and production cost reduction. In contrast, local firms interconnect their own R&D departments via ICTs to enhance their business performance in broader areas than MNCs/JVs, including the development of export markets.
Nationwide Epidemiological Survey of Delayed Endolymphatic Hydrops in Japan
No full text富山大学博士（医学）Article富山大学・富医薬博乙第94号・伊東 伸祐・2023/01/25
公表論文
Shinsuke Ito, Hiromasa Takakura, Katsuichi Akaogi, Hideo Shojaku, Noriaki Takeda, Mamoru Suzuki, Yukio Watanabe, Mitsuhiro Aoki, Katsumi Doi, Tetsuo Ikezono, Akinobu Kakigi, Tadashi Kitahara, Izumi Koizuka, Toshihisa Murofushi, Hideaki Naganuma, Koichi Omori, Katsumasa Takahashi, Masaya Takumida, Shin-ichi Usami & Hiroshi Yamashita (2022) A 14-year nationwide epidemiological analysis of delayed endolymphatic hydrops in Japan, Acta Oto-Laryngologica, 142:7-8, 568-574, DOI: 10.1080/00016489.2022.210814
ヘイコウ POISEUILLE ナガレ ノ フアンテイセイ ニ タイスル ケイサンキ エンヨウ ショウメイ ケイサン カガク ノ キバン ギジュツ トシテノ コウソク アルゴリズム ト ソノ シュウヘン
No full textSynthesis of Dibenzoxasilepine Using Ring Expansion Reaction of a Pentacoordinate Silicon Intermediate
No full textWatanabe K., Sato M., Takehara T., et al. Synthesis of Dibenzoxasilepine Using Ring Expansion Reaction of a Pentacoordinate Silicon Intermediate. Advanced Synthesis and Catalysis , (2024); https://doi.org/10.1002/adsc.202401125.Dibenzoxasilepine is an important skeleton in both synthetic organic and medicinal chemistry. Here, we have succeeded in obtaining it in higher yield than the conventional method, elucidating for the first time the rearrangement tendency of the two aromatic rings during the ring expansion reaction on the cyclic pentacoordinate silicon intermediate
交互脈を伴う拡張型心筋症患者におけるベースラインの血圧と左室逆リモデリングに関する研究
No full text新潟大学Niigata University博士（医学）Objective Spontaneous mechanical alternans (MA), or pulsus alternans, has been observed in heart failure patients with hypertension or tachycardia for 150 years and is considered a sign of a poor prognosis. How-ever, in some dilated cardiomyopathy (DCM) patients with MA, optimal medical therapy (OMT) brings left ventricular reverse remodeling (LVRR), a preferable prognostic indicator. This study examined the probability of LVRR in DCM patients with spontaneous MA and whether or not LVRR can be predicted by the baseline blood pressure or heart rate. Methods We conducted a single-center, retrospective observational study of newly diagnosed DCM patients from January 2017 to December 2020. Results Thirty-three newly diagnosed DCM patients were retrospectively examined. Spontaneous MA was observed during diagnostic cardiac catheterization in at least 1 of the pressure waveforms of the aorta, left ventricle, pulmonary artery, or right ventricle in 10 patients (30%) (MA-group). LVRR after OMT was achieved roughly equally in the MA group (6 of 10, 60%) and the non-MA group (12 of 23, 52%). In the MA group, those who achieved LVRR had a significantly higher baseline systolic aortic pressure (more than 120 mmHg in all 6 patients) than those who did not, although the baseline heart rate did not show a signifi-cant correlation with LVRR. In contrast, in the non-MA group, LVRR was unrelated to the baseline aortic pressure or heart rate. Conclusion The probability of LVRR in newly-diagnosed DCM patients with spontaneous MA was similar to that in those without spontaneous MA. Spontaneous MA may not necessarily be a sign of a poor progno-sis if observed in patients with a preserved blood pressure.Mitsuhiro Watanabe, Takeshi Kashimura, Mitsuo Ishizuka, Mayumi Kase, Ryohei Sakai, Shinya Fujiki, Tsugumi Takayama, Shiro Ishihara, Kazuyuki Ozaki, Takayuki Inomata, Baseline Blood Pressure and Left Ventricular Reverse Remodeling in Dilated Cardiomyopathy with Spontaneous Mechanical Alternans, Internal Medicine, 2023, Volume 62, Issue 12, Pages 1707-1713, Released on J-STAGE June 15, 2023, Advance online publication November 09, 2022, Online ISSN 1349-7235, Print ISSN 0918-2918, https://doi.org/10.2169/internalmedicine.0711-22, https://www.jstage.jst.go.jp/article/internalmedicine/62/12/62_0711-22/_article/-char/en新大博（医）第1189
Separation and collection of coarse aggregate from waste concrete by electric pulsed power
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Enclosing Potential Functions of an Inverse Elliptic Eigenvalue Problem with Finite Data (Numerical Solution of Partial Differential Equations and Related Topics II)
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