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How to Prove Riemann Conjecture by Riemann’s Four Theorems
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作者 chuanmiao chen 《Advances in Pure Mathematics》 2024年第8期619-632,共15页
Riemann (1859) had proved four theorems: analytic continuation ζ(s), functional equation ξ(z)=G(s)ζ(s)(s=1/2+iz, z=t−i(σ−1/2)), product expression ξ1(z)and Riemann-Siegel formula Z(z), and proposed Riemann conjec... Riemann (1859) had proved four theorems: analytic continuation ζ(s), functional equation ξ(z)=G(s)ζ(s)(s=1/2+iz, z=t−i(σ−1/2)), product expression ξ1(z)and Riemann-Siegel formula Z(z), and proposed Riemann conjecture (RC): All roots of ξ(z)are real. We have calculated ξand ζ, and found that ξ(z)is alternative oscillation, which intuitively implies RC, and the property of ζ(s)is not good. Therefore Riemann’s direction is correct, but he used the same notation ξ(t)=ξ1(t)to confuse two concepts. So the product expression only can be used in contraction. We find that if ξhas complex roots, then its structure is destroyed, so RC holds. In our proof, using Riemann’s four theorems is sufficient, needn’t cite other results. Hilbert (1900) proposed Riemann hypothesis (RH): The non-trivial roots of ζhave real part 1/2. Of course, RH also holds, but can not be proved directly by ζ(s). 展开更多
关键词 Riemann Conjecture ZETA-FUNCTION Xi-Function Functional Equation Product Expression CONTRADICTION
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Proof of Riemann Conjecture Based on Contradiction between Xi-Function and Its Product Expression
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作者 chuanmiao chen 《Advances in Pure Mathematics》 2023年第7期463-472,共10页
Riemann proved three results: analytically continue ζ(s) over the whole complex plane s =σ + it with a pole s =1;(Theorem A) functional equation ξ(t) = G(s<sub>0</sub>)ζ (s<sub>0</sub>), s&... Riemann proved three results: analytically continue ζ(s) over the whole complex plane s =σ + it with a pole s =1;(Theorem A) functional equation ξ(t) = G(s<sub>0</sub>)ζ (s<sub>0</sub>), s<sub>0</sub> =1/2 + it and (Theorem B) product expression ξ<sub>1</sub>(t) by all roots of ξ(t). He stated Riemann conjecture (RC): All roots of ξ (t) are real. We find a mistake of Riemann: he used the same notation ξ(t) in two theorems. Theorem B must contain complex roots;it conflicts with RC. Thus theorem B can only be used by contradiction. Our research can be completed on s<sub>0</sub> =1/2 + it. Using all real roots r<sub>k</sub><sub> </sub>and (true) complex roots z<sub>j</sub> = t<sub>j</sub> + ia<sub>j</sub> of ξ (z), define product expressions w(t), w(0) =ξ(0) and Q(t) > 0, Q(0) =1 respectively, so ξ<sub>1</sub>(t) = w(t)Q(t). Define infinite point-set L(ω) = {t : t ≥10 and |ζ(s<sub>0</sub>)| =ω} for small ω > 0. If ξ(t) has complex roots, then ω =ωQ(t) on L(ω). Finally in a large interval of the first module |z<sub>1</sub>|>>1, we can find many points t ∈ L(ω) to make Q(t) . This contraction proves RC. In addition, Riemann hypothesis (RH) ζ for also holds, but it cannot be proved by ζ. 展开更多
关键词 Riemann Conjecture Xi-Function Functional Equation Product Expression Multiplicative Group CONTRADICTION
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Local Geometric Proof of Riemann Conjecture 被引量:3
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作者 chuanmiao chen 《Advances in Pure Mathematics》 2020年第10期589-610,共22页
Riemann hypothesis (RH) is a difficult problem. So far one doesn’t know how to go about it. Studying <i>ζ</i> and using analysis method likely are two incor-rect guides. Actually, a unique hope may study... Riemann hypothesis (RH) is a difficult problem. So far one doesn’t know how to go about it. Studying <i>ζ</i> and using analysis method likely are two incor-rect guides. Actually, a unique hope may study Riemann function <img alt="" src="Edit_8fcdfff5-6b95-42a4-8f47-2cabe2723dfc.bmp" />, <img alt="" src="Edit_6ce3a4bd-4c68-49e5-aabe-dec3e904e282.bmp" />, <img alt="" src="Edit_29ea252e-a81e-4b21-a41c-09209c780bb2.bmp" /> by geometric analysis, which has the symmetry: v=0 if <i>β</i>=0, and basic expression <img alt="" src="Edit_bc7a883f-312d-44fd-bcdd-00f25c92f80a.bmp" />. We show that |u| is single peak in each root-interval <img alt="" src="Edit_d7ca54c7-4866-4419-a4bd-cbb808b365af.bmp" /> of <i>u</i> for fixed <em>β</em> ∈(0,1/2]. Using the slope u<sub>t</sub>, we prove that <i>v</i> has opposite signs at two end-points of I<sub>j</sub>. There surely exists an inner point such that , so {|u|,|v|/<em>β</em>} form a local peak-valley structure, and have positive lower bound <img alt="" src="Edit_bac1a5f6-673e-49b6-892c-5adff0141376.bmp" /> in I<sub>j</sub>. Because each <i>t</i> must lie in some I<sub>j</sub>, then ||<em>ξ</em>|| > 0 is valid for any <i>t</i> (<i>i.e.</i> RH is true). Using the positivity <img alt="" src="Edit_83c3d2cf-aa7e-4aba-89f5-0eb44659918a.bmp" /> of Lagarias (1999), we show the strict monotone <img alt="" src="Edit_87eb4e9e-bc7b-43e3-b316-5dcf0efaf0d5.bmp" /> for <i>β</i> > <i>β</i><sub>0</sub> ≥ 0 , and the peak-valley structure is equiva-lent to RH, which may be the geometric model expected by Bombieri (2000). This research follows Liuhui’s methodology: “Computing can detect the un-known and method”.</i> 展开更多
关键词 Riemann Conjecture Local Geometric Proof Symmetry Peak-Valley Struc-ture EQUIVALENCE Liuhui’s Methodology
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Geometric Proof of Riemann Conjecture 被引量:2
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作者 chuanmiao chen 《Advances in Pure Mathematics》 2021年第4期334-345,共12页
This paper proves Riemann conjecture (RH), <em>i.e</em>., that all the zeros in critical region of Riemann <span style="white-space:nowrap;"><em><span style="white-space:nowra... This paper proves Riemann conjecture (RH), <em>i.e</em>., that all the zeros in critical region of Riemann <span style="white-space:nowrap;"><em><span style="white-space:nowrap;"><em>ξ</em><span style="white-space:normal;"> </span></span></em></span>-function lie on symmetric line <span style="white-space:nowrap;"><em>σ</em></span> =1/2 . Its proof is based on two important properties: the symmetry and alternative oscillation for <span style="white-space:nowrap;"><em><em>ξ</em><span style="white-space:normal;"> </span></em>=<em> u </em>+<em> iv</em></span> . Denote <img src="Edit_317839cd-bad0-44d8-b081-c473bcb336f1.png" width="170" height="15" alt="" />. Riemann proved that u is real and <em>v</em> <span style="white-space:nowrap;">≡ </span>0 for <span style="white-space:nowrap;"><em><span style="white-space:nowrap;">β</span></em> =0</span> (the symmetry). We prove that the zeros of u and v for <em>β</em> <span style="white-space:nowrap;">> 0</span> are alternative, so <span style="white-space:nowrap;"><em>u</em> (<em>t</em>,0)</span> is the single peak. A geometric model was proposed. <img src="Edit_27688061-de42-4bce-ad80-6fb3dd1e3d4b.png" width="85" height="27" alt="" /> is called the root-interval of <em>u </em>(<em>t</em>,<em style="white-space:normal;">β</em>) , if |<span style="white-space:nowrap;"><em>u</em>| <em>> </em>0</span> is inside <em>I</em><sub><em>j</em> </sub>and <span style="white-space:nowrap;"><em>u</em> = 0</span> is at its two ends. If |<em>u</em> (<em style="white-space:normal;">t</em><span style="white-space:normal;">,</span><em style="white-space:normal;">β</em>)| has only one peak on each <em style="white-space:normal;">I</em><sub style="white-space:normal;"><em>j</em></sub>, which is called the single peak, else called multiple peaks (it will be proved that the multiple peaks do not exist). The important expressions of u and v for <em style="white-space:normal;">β</em><span style="white-space:normal;"> </span>> 0 were derived. By <img src="Edit_b6369c2e-6a6d-4e1a-8a75-00d743cecaf1.png" width="240" height="28" alt="" />, the peak <em style="white-space:normal;">u </em><span style="white-space:normal;">(</span><em style="white-space:normal;">t</em><span style="white-space:normal;">,</span><em style="white-space:normal;">β</em><span style="white-space:normal;">)</span> will develop toward its convex direction. Besides, <em style="white-space:normal;">u<sub>t</sub> </em><span style="white-space:normal;">(</span><em style="white-space:normal;">t</em><span style="white-space:normal;">,</span><em style="white-space:normal;">β</em><span style="white-space:normal;">)</span> has opposite signs at two ends <em>t</em> = <em>t<sub>j</sub></em><sub> </sub>, <em>t<sub>j+1</sub></em> of <em>I<sub>j </sub></em>, <img src="Edit_be3f0d63-1d24-4165-ac2c-141c9a47d1c8.png" width="145" height="28" alt="" /> also does, then there exists some inner point <span style="white-space:nowrap;"><em>t</em>′</span> such that <span style="white-space:nowrap;"><em>v</em><em></em> (<em>t′</em>,<em>β</em>) = 0</span>. Therefore {|<em>u</em>|,|<em>v</em>|/<em>β</em>} in <em>I<sub>j</sub></em><sub> </sub>form a peak-valley structure such that <img src="Edit_70bb530a-662f-464a-b3c8-4d5625fbf679.png" width="180" height="22" alt="" /> has positive lower bound independent of <em>t</em> <span style="white-space:nowrap;">∈ </span><em>I<sub>j</sub></em><sub> </sub>(<em>i.e</em>. RH holds in <em style="white-space:normal;">I<sub>j</sub></em><sub style="white-space:normal;"> </sub>). As <em style="white-space:normal;">u </em><span style="white-space:normal;">(</span><em style="white-space:normal;">t</em><span style="white-space:normal;">,</span><em style="white-space:normal;">β</em><span style="white-space:normal;">)</span> does not have the finite condensation point (unless <span style="white-space:nowrap;"><em>u</em> = <em>cons</em><em>t</em>.</span>), any finite t surely falls in some <em style="white-space:normal;">I<sub>j</sub></em><sub style="white-space:normal;"> </sub>, then <img src="Edit_166a9981-aac8-476b-a29a-496763297b35.png" width="50" height="23" alt="" /> holds for any t (RH is proved). Our previous paper “Local geometric proof of Riemann conjecture” (APM, V.10:8, 2020) has two defects, this paper has amended these defects and given a complete proof of RH. 展开更多
关键词 Riemann Conjecture Geometric Analysis SYMMETRY Alternative Oscillation Single Peak Peak-Valley Structure
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Geometric Proof of Riemann Conjecture (Continued) 被引量:2
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作者 chuanmiao chen 《Advances in Pure Mathematics》 2021年第9期771-783,共13页
This paper will prove Riemann conjecture(RC): All zeros of <span style="white-space:nowrap;"><span style="white-space:nowrap;"><em>ξ</em></span>(<span style="... This paper will prove Riemann conjecture(RC): All zeros of <span style="white-space:nowrap;"><span style="white-space:nowrap;"><em>ξ</em></span>(<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><em>τ</em></span></span></span></span>)</span> lie on critical line. Denote <img src="Edit_189dc2b2-73ef-4036-9f06-ecf8a47fe58b.png" width="140" height="16" alt="" />, and <img src="Edit_a8ec55cb-e4c4-4156-ba23-ae01a31d1bc8.png" width="110" height="22" alt="" /> on critical line. We have found two mysteries in Riemann’s paper. <em>The first mystery</em> is the equivalence: <img src="Edit_3c075830-3c6c-4a23-9851-5b7d219e8000.png" width="140" height="21" alt="" /> is uniquely determined by its initial value <span style="white-space:nowrap;"><em>u</em> (<em>t</em>)</span>. <em>The second mystery</em> is Riemamm conjecture 2 (RC2): Using all zeros <span style="white-space:nowrap;"><em>t<sub>j</sub> </em></span>of <em>u</em> (<em>t</em>) can uniquely express <img src="Edit_b15d9c18-b55b-49e3-97a1-d2e03ccb6343.png" width="175" height="23" alt="" />. We find that the proof of RC is hidden in it. Our basic idea as follows. Consider functional equation <img src="Edit_f5295ff4-90b2-4465-851a-cad140b181c8.png" width="305" height="20" alt="" />. It is known that on critical line <img src="Edit_b45bff49-6d09-456b-9d1f-4259c66293d3.png" width="310" height="23" alt="" /> and <img src="Edit_4182ba79-0fcb-4f84-b7e7-c7574406596e.png" width="85" height="26" alt="" />, then we have the upper bound of growth <img src="Edit_d3d84d75-cc56-47b8-a9a7-ef8a9a5f07b1.png" width="250" height="33" alt="" /> To prove RC2 (or RC), by contradiction. If <span style="white-space:nowrap;"><em>ξ</em>(<em>τ</em>)</span> has conjugate complex roots <em>t</em>'<span style="white-space:nowrap;">±<em>i</em><span style="white-space:nowrap;"><em>β</em></span>'’</span>, <span style="white-space:nowrap;"><em>β</em>'>0</span>, <em>R</em><sup>2</sup>=t'<sup>2</sup>+<span style="white-space:nowrap;"><em>β</em>'<sup>2</sup></span>, by symmetry <span style="white-space:nowrap;"><em>ξ</em>(<em>τ</em>)=<span style="white-space:nowrap;"><em>ξ</em>(-<em>τ</em>)</span></span>, then -(<em>t</em>'<span style="white-space:nowrap;">±<em>i</em><em>β</em>''</span>) do yet. So <em>ξ</em> must contain four factors. Then <em>u</em>(<em>t</em>) contains a real factor <img src="Edit_ac03c1a5-0480-4efa-aac4-7788852a42a9.png" width="225" height="22" alt="" /> and <span style="white-space:nowrap;">ln|<em>u</em>(<em>t</em>)|</span> contains a term (the lower bound) <img src="Edit_6e94ad71-a310-4717-99ee-90384b0d89ba.png" width="230" height="19" alt="" /> which contradicts to the growth above. So <span style="white-space:nowrap;"><em>ξ</em></span> can not have the complex roots and <em>u</em>(<em>t</em>) does not have the factor <em>p</em>(<em>t</em>). Therefore both RC2 and RC are proved. We have seen that the two-dimensional problem is reduced to one-dimension and the one-dimensional <span style="white-space:nowrap;"><em>u</em>(<em>t</em>)</span> is reduced to its product expression. Perhaps this is close to the original idea of Riemann. Other results are also discussed by geometric analysis in the last section. 展开更多
关键词 RC EQUIVALENCE RC2 Product Expression Single Peak Multiple Zeros
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Proof of Riemann Conjecture 被引量:1
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作者 chuanmiao chen 《Advances in Pure Mathematics》 2022年第5期374-391,共18页
Using translation β = σ &#8722;1/2 and rotation s =σ + it = 1/2 + iz, z = t &#8722;iβ, Riemann got two results: (Theorem A) the functional equation ξ(z) = G(s)ξ(s), where , and (Theorem B) the product ex... Using translation β = σ &#8722;1/2 and rotation s =σ + it = 1/2 + iz, z = t &#8722;iβ, Riemann got two results: (Theorem A) the functional equation ξ(z) = G(s)ξ(s), where , and (Theorem B) the product expression , where z<sub>j</sub> are all roots of ξ(z), including complex roots. He proposed Riemann conjecture (RC): All roots of ξ(z) are real. As the product expression can only be used as a tool of contradiction, we prove RC by contradiction. To avoid the zeros of ξ(1/2 + it), define a subset . We have basic estimate , on L (R). One can construct by all real roots t<sub>j</sub> of ξ(t). If ξ has no complex roots, then w(t) = G(s)ξ(s) for s = 1/2 + it. If the product expression has a complex root z'=t' &#8722;iα, where 0 a ≤ 1/2, R' = |z′| > 10, then ξ(z) has four complex roots ±(t′ ± iα), and should contain fourth order factor p(z), i.e. ξ(z) = w(z)p(z). But p(z) can not be contained in ξ(s), as we have on L(R) and p(t) ≥ 0.5(t/R)<sup>4</sup> . As a result, we can rewrite ξ(t) = w(t)p(t) =G(s)ξ(s)p(t) on and get This contradicts the basic estimate. Therefore ξ(z) has no complex roots and RC holds. 展开更多
关键词 Riemann Conjecture Distribution of Zeros Entire Function SYMMETRY Functional Equation Product Expression
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Superconvergence of Continuous Finite Elements with Interpolated Coeffcients for Initial Value Problems of Nonlinear Ordinary Differential Equation
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作者 Zhiguang Xiong chuanmiao chen 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 2007年第1期37-44,共8页
In this paper, n-degree continuous finite element method with interpolated coefficients for nonlinear initial value problem of ordinary differential equation is introduced and analyzed. An optimal superconvergence u-u... In this paper, n-degree continuous finite element method with interpolated coefficients for nonlinear initial value problem of ordinary differential equation is introduced and analyzed. An optimal superconvergence u-uh = O(hn+2), n ≥ 2, at (n + 1)-order Lobatto points in each element respectively is proved. Finally the theoretical results are tested by a numerical example. 展开更多
关键词 超收敛 有限元 原始价值 常微分方程
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The Symmetry of Riemann <i>ξ</i>-Function
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作者 chuanmiao chen 《Advances in Pure Mathematics》 2020年第8期464-470,共7页
To prove RH, studying <span style="white-space:nowrap;"><em>ζ</em> </span>and using pure analysis method likely are two kinds of the incorrect guide. Actually, a unique hope may stud... To prove RH, studying <span style="white-space:nowrap;"><em>ζ</em> </span>and using pure analysis method likely are two kinds of the incorrect guide. Actually, a unique hope may study Riemann function <img src="Edit_b4e53620-7ae2-4a2b-aee0-351c62aef8cd.png" width="250" height="20" alt="" /> by geometric analysis, which has the symmetry: <span style="white-space:nowrap;"><em>v</em></span> = 0 if <span style="white-space:nowrap;"><em>β</em></span> = 0, and <img src="Edit_8c67c5d7-c1d4-4cad-8792-78e4bd172ebd.png" width="150" height="28" alt="" /> Assume that |<em>u</em>| is single peak in each root-interval <img src="Edit_a91df253-2965-4b03-8033-54aba2e23036.png" width="85" height="27" alt="" /> of <em>u</em> for any fixed <span style="white-space:nowrap;"><em>β</em></span> <span style="white-space:nowrap;">∈ (0,1/2]</span>, using the slope <em>u</em><sub><em>t </em></sub>of the single peak, we prove that <em>v</em> has opposite signs at two end-points of <em>I</em><sub><em>j</em></sub>, there surely is an inner point so that <em>v</em> = 0, so {|<em>u</em>|,|<em>v</em>|/<span style="white-space:nowrap;"><em>β</em></span>}form a local peak-valley structure, and have positive lower bound <img src="Edit_04798c0f-8e21-4a3a-ae12-0e28b01ee348.png" width="167" height="22" alt="" />in <em>I</em><sub><em>j</em></sub>. Because each <em>t</em> must lie in some <em style="white-space:normal;">I</em><sub style="white-space:normal;"><em>j</em></sub> , then ||<span style="white-space:nowrap;"><em>ξ</em></span>|| > 0 is valid for any <em>t</em>. In this way, the summation process of <span style="white-space:nowrap;"><em>ξ</em></span> is avoided. We have proved the main theorem: Assume that <em>u</em> (<em>t</em>, <span style="white-space:nowrap;"><em>β</em></span>) is single peak, then RH is valid for any <img src="Edit_ed8521a3-63b1-417f-a3b0-a3c790bae519.png" width="140" height="19" alt="" />. If using the equivalence of Lagarias (1999), the assumption of single peak can be canceled. Therefore our new thinking is that we have found the local peak-valley structure of <span style="white-space:nowrap;"><em>ξ</em></span>, which may be the geometry structure expected by Bombieri (2000), and proposed a basic framework of proving RH by geometric analysis. 展开更多
关键词 Riemann ξ-Function SYMMETRY Peak-Valley Structure Single Peak RH
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ON EXTRAPOLATION CASCADIC MULTIGRID METHOD 被引量:11
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作者 chuanmiao chen Zhong-Ci Shi Hongling Hu 《Journal of Computational Mathematics》 SCIE CSCD 2011年第6期684-697,共14页
Based on an asymptotic expansion of (bi)linear finite elements, a new extrapolation formula and extrapolation cascadic multigrid method (EXCMG) are proposed. The key ingredients of the proposed methods are some ne... Based on an asymptotic expansion of (bi)linear finite elements, a new extrapolation formula and extrapolation cascadic multigrid method (EXCMG) are proposed. The key ingredients of the proposed methods are some new extrapolations and quadratic interpolations, which are used to provide better initial values on the refined grid. In the case of triple grids, the errors of the new initial values are analyzed in detail. The numerical experiments show that EXCMG has higher accuracy and efficiency. 展开更多
关键词 Cascadic multigrid Finite element New extrapolation Error analysis.
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FINITE ELEMENT METHOD WITH SUPERCONVERGENCE FOR NONLINEAR HAMILTONIAN SYSTEMS 被引量:4
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作者 chuanmiao chen Qiong Tang Shufang Hu 《Journal of Computational Mathematics》 SCIE CSCD 2011年第2期167-184,共18页
This paper is concerned with the finite element method for nonlinear Hamiltonian systems from three aspects: conservation of energy, symplicity, and the global error. To study the symplecticity of the finite element ... This paper is concerned with the finite element method for nonlinear Hamiltonian systems from three aspects: conservation of energy, symplicity, and the global error. To study the symplecticity of the finite element methods, we use an analytical method rather than the commonly used algebraic method. We prove optimal order of convergence at the nodes tn for mid-long time and demonstrate the symplecticity of high accuracy. The proofs depend strongly on superconvergence analysis. Numerical experiments show that the proposed method can preserve the energy very well and also can make the global trajectory error small for long time. 展开更多
关键词 Nonlinear Hamiltonian systems Finiteelement method SUPERCONVERGENCE Energy conservation SYMPLECTICITY Trajectory.
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Superconvergence for triangular cubic elements 被引量:2
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作者 chuanmiao chen Jicheng Jin Shi Shu 《Chinese Science Bulletin》 SCIE EI CAS 1999年第1期47-49,共3页
A new structure of superconvergence for the cubic triangular finite element approximation u/2 to a second-order elliptic problem Au=f is studied based on some orthogonal expansions in an interval. Suppose that Ω is a... A new structure of superconvergence for the cubic triangular finite element approximation u/2 to a second-order elliptic problem Au=f is studied based on some orthogonal expansions in an interval. Suppose that Ω is a convex polygonal domain with boundary L, its triangulation is uniform and T<sub>h</sub> is a set of vertexes and side midpoints of all elements. Then u<sub>h</sub> itself has no superconvergence points in Ω, while in any interior subdomain Ω<sub>0</sub> the average gradient Du<sub>h</sub> has superconvergence D(d<sub>h</sub>-u)=O(h<sup>m+1</sup>lnh) at z∈T<sub>h</sub>∩Ω<sub>0</sub>(no other superconvergence points). Furthermore, prescribe u=0 on L<sub>1</sub>.Then the superconvergence near L<sub>1</sub> will surely disappear; if αa<sub>v</sub>u+bu=0 on L<sub>3</sub>, where v is the conormal direction, the numercal experiments show superconvergence up to L<sub>3</sub>(the case of A=-Δ and b=0 has already been proved). 展开更多
关键词 SUPERCONVERGENCE TRIANGULAR CUBIC ELEMENT FINITE ELEMENT approxination.
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TIME-EXTRAPOLATION ALGORITHM (TEA) FOR LINEAR PARABOLIC PROBLEMS 被引量:2
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作者 Hongling Hu chuanmiao chen Kejia Pan 《Journal of Computational Mathematics》 SCIE CSCD 2014年第2期183-194,共12页
The fast solutions of Crank-Nicolson scheme on quasi-uniform mesh for parabolic prob- lems are discussed. First, to decrease regularity requirements of solutions, some new error estimates are proved. Second, we analyz... The fast solutions of Crank-Nicolson scheme on quasi-uniform mesh for parabolic prob- lems are discussed. First, to decrease regularity requirements of solutions, some new error estimates are proved. Second, we analyze the two characteristics of parabolic discrete scheme, and find that the efficiency of Multigrid Method (MG) is greatly reduced. Nu- merical experiments compare the efficiency of Direct Conjugate Gradient Method (DCG) and Extrapolation Cascadic Multigrid Method (EXCMG). Last, we propose a Time- Extrapolation Algorithm (TEA), which takes a linear combination of previous several level solutions as good initial values to accelerate the rate of convergence. Some typical extrapolation formulas are compared numerically. And we find that under certain accuracy requirement, the CG iteration count for the 3-order and 7-level extrapolation formula is about 1/3 of that of DCG's. Since the TEA algorithm is independent of the space dimension, it is still valid for quasi-uniform meshes. As only the finest grid is needed, the proposed method is regarded very effective for nonlinear parabolic problems. 展开更多
关键词 Parabolic problem Crank-Nicolson scheme Error estimates Time-extrapolationalgorithm CG-iteration.
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Implicit DG Method for Time Domain Maxwell’s Equations Involving Metamaterials 被引量:1
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作者 Jiangxing Wang Ziqing Xie chuanmiao chen 《Advances in Applied Mathematics and Mechanics》 SCIE 2015年第6期796-817,共22页
An implicit discontinuous Galerkin method is introduced to solve the timedomain Maxwell’s equations in metamaterials.The Maxwell’s equations in metamaterials are represented by integral-differential equations.Our sc... An implicit discontinuous Galerkin method is introduced to solve the timedomain Maxwell’s equations in metamaterials.The Maxwell’s equations in metamaterials are represented by integral-differential equations.Our scheme is based on discontinuous Galerkin method in spatial domain and Crank-Nicolson method in temporal domain.The fully discrete numerical scheme is proved to be unconditionally stable.When polynomial of degree at most p is used for spatial approximation,our scheme is verified to converge at a rate of O(τ^(2)+h^(p)+1/2).Numerical results in both 2D and 3D are provided to validate our theoretical prediction. 展开更多
关键词 Maxwell’s equations METAMATERIALS fully disctete DG method L2-stability L2-error estimate.
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An Extrapolation Cascadic MultigridMethod for Elliptic Problems on Reentrant Domains
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作者 Kejia Pan Dongdong He chuanmiao chen 《Advances in Applied Mathematics and Mechanics》 SCIE 2017年第6期1347-1363,共17页
This paper proposes an extrapolation cascadic multigrid(EXCMG)method to solve elliptic problems in domains with reentrant corners.On a class ofλ-graded meshes,we derive some new extrapolation formulas to construct a ... This paper proposes an extrapolation cascadic multigrid(EXCMG)method to solve elliptic problems in domains with reentrant corners.On a class ofλ-graded meshes,we derive some new extrapolation formulas to construct a high-order approximation to the finite element solution on the next finer mesh using the numerical solutions on two-level of grids(current and previous grids).Then,this high-order approximation is used as the initial guess to reduce computational cost of the conjugate gradient method.Recursive application of this idea results in the EXCMG method proposed in this paper.Finally,numerical results for a crack problem and an L-shaped problem are presented to verify the efficiency and effectiveness of the proposed EXCMG method. 展开更多
关键词 Richardson extrapolation Cascadicmultigrid gradedmesh elliptic problems corner singularity
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Numerical Integration over Pyramids
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作者 chuanmiao chen Michal Krızek Liping Liu 《Advances in Applied Mathematics and Mechanics》 SCIE 2013年第3期309-320,共12页
Pyramidal elements are often used to connect tetrahedral and hexahedral elements in the finite element method.In this paper we derive three new higher order numerical cubature formulae for pyramidal elements.
关键词 Reference pyramidal element nonlinear systems of algebraic equations Bramble-Hilbert lemma TRIANGULAR tetrahedral and pyramidal numbers
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