In this paper, we prove the following estimate on exponential sums over primes: Let κ≥1,βκ=1/2+log κ/log2, x≥2 and α=a/q+ λ subject to (a, q) = 1, 1≤a≤q, and λ ∈ R. Then As an application, we prove that wi...In this paper, we prove the following estimate on exponential sums over primes: Let κ≥1,βκ=1/2+log κ/log2, x≥2 and α=a/q+ λ subject to (a, q) = 1, 1≤a≤q, and λ ∈ R. Then As an application, we prove that with at most O(N2/8+ε) exceptions, all positive integers up to N satisfying some necessary congruence conditions are the sum of three squares of primes. This result is as strong as what has previously been established under the generalized Riemann hypothesis.展开更多
It is proved that every large integerN≡5 (mod 24) can be written as $N = p_1^2 + ... + p_5^2 $ with each primep j satisfying $|p_j - \sqrt {N/5} | \leqslant N^{\frac{{12}}{{25}} + E} $ , which gives a short interval ...It is proved that every large integerN≡5 (mod 24) can be written as $N = p_1^2 + ... + p_5^2 $ with each primep j satisfying $|p_j - \sqrt {N/5} | \leqslant N^{\frac{{12}}{{25}} + E} $ , which gives a short interval version of a classical theorem of Hua.展开更多
It is proved that each su?ciently large integer N ≡ 5 (mod24) can be written as N = p21+p22+p23+p24+p25 with |pj? N/5| ≤ U = N 12? 135+ε, where pj are primes. This result, which is obtained by an iterative method a...It is proved that each su?ciently large integer N ≡ 5 (mod24) can be written as N = p21+p22+p23+p24+p25 with |pj? N/5| ≤ U = N 12? 135+ε, where pj are primes. This result, which is obtained by an iterative method and a hybrid estimate for Dirichlet polynomial, improves the previous results in this direction.展开更多
It is proved that with at most O(N^(11/12+ε)) exceptions, all positiveintegers n ≤ N satisfying some necessary congruence conditions are the sum of three squares ofprimes. This improves substantially the previous re...It is proved that with at most O(N^(11/12+ε)) exceptions, all positiveintegers n ≤ N satisfying some necessary congruence conditions are the sum of three squares ofprimes. This improves substantially the previous results in this direction.展开更多
In this paper we establish one new estimate on exponential sums over primes in short intervals. As an application of this result, we sharpen Hua's result by proving that each sufficiently large integer N congruent...In this paper we establish one new estimate on exponential sums over primes in short intervals. As an application of this result, we sharpen Hua's result by proving that each sufficiently large integer N congruent to 5 modulo 24 can be written as N = p12+p22+p32+p42+p52, with |pj-(N/5)^(1/2)|≤U = N1/2-1/20+ε, where pj are primes. This result is as good as what one can obtain from the generalized Riemann hypothesis.展开更多
讨论了基于节点的有限元方法的网格生成算法及其产生的不一致性问题,提出了基于D e launay三角剖分的唯一性来克服网格不一致性现象的思想,并建议使用局部区域分割方法合理地确定探索圆半径,使中心节点的探索圆包含它的所有卫星点,进而...讨论了基于节点的有限元方法的网格生成算法及其产生的不一致性问题,提出了基于D e launay三角剖分的唯一性来克服网格不一致性现象的思想,并建议使用局部区域分割方法合理地确定探索圆半径,使中心节点的探索圆包含它的所有卫星点,进而确保算法无不一致性。理论分析和算例表明了该方法的可靠性及有效性。展开更多
The present study proposes a novel method based on the geometric theory for measuring the distribution of bubble swarms in the circular region of a direct-contact heat exchanger.It was determined that the mixing is un...The present study proposes a novel method based on the geometric theory for measuring the distribution of bubble swarms in the circular region of a direct-contact heat exchanger.It was determined that the mixing is uniform when the average distance between the bubble swarms in the unit circular region is approximately 0.9054,which is the standard reference value.The effect of sample size(i.e.,the number of bubbles)on mixing uniformity was investigated to determine the optimal sample size.It was verified that the metric's accuracy and stability were higher with a sample size of 155.Accordingly,it was proposed to increase the sample size by filling irregular bubbles using a segmentation method,which enabled a further accurate assessment of the mixing uniformity.The mixing uniformity of bubble swarms in the circular region and its maximum internal connection with the square region was accurately quantified.It was revealed that the relative average error increased by approximately 3.47% due to information loss.The proposed method was demonstrated to be rotationally invariant.The present study provided novel insights into evaluating mixing uniformity,which would guide enhanced heat transfer and the effective evaluation of the spatiotemporal characteristics of transient mixing in circular regions or the cross-sections of chemical transport pipelines.展开更多
基金The author is supported by Post-Doctoral Fellowsbip of The University of Hong Kong.
文摘In this paper, we prove the following estimate on exponential sums over primes: Let κ≥1,βκ=1/2+log κ/log2, x≥2 and α=a/q+ λ subject to (a, q) = 1, 1≤a≤q, and λ ∈ R. Then As an application, we prove that with at most O(N2/8+ε) exceptions, all positive integers up to N satisfying some necessary congruence conditions are the sum of three squares of primes. This result is as strong as what has previously been established under the generalized Riemann hypothesis.
文摘It is proved that every large integerN≡5 (mod 24) can be written as $N = p_1^2 + ... + p_5^2 $ with each primep j satisfying $|p_j - \sqrt {N/5} | \leqslant N^{\frac{{12}}{{25}} + E} $ , which gives a short interval version of a classical theorem of Hua.
文摘It is proved that each su?ciently large integer N ≡ 5 (mod24) can be written as N = p21+p22+p23+p24+p25 with |pj? N/5| ≤ U = N 12? 135+ε, where pj are primes. This result, which is obtained by an iterative method and a hybrid estimate for Dirichlet polynomial, improves the previous results in this direction.
基金Supported by The National Science Foundation(Grants #10125101 and #10131010)by a Ministry of Education Major Grant Program in Sciences and Technology
文摘It is proved that with at most O(N^(11/12+ε)) exceptions, all positiveintegers n ≤ N satisfying some necessary congruence conditions are the sum of three squares ofprimes. This improves substantially the previous results in this direction.
基金supported by the National Natural Science Foundation of China(Grant Nos.10125101&10531060)a Major Grant Program in Science and Technology by the Ministry of EducationTianyuan Mathematics Foundation(Grant No.10526028).
文摘In this paper we establish one new estimate on exponential sums over primes in short intervals. As an application of this result, we sharpen Hua's result by proving that each sufficiently large integer N congruent to 5 modulo 24 can be written as N = p12+p22+p32+p42+p52, with |pj-(N/5)^(1/2)|≤U = N1/2-1/20+ε, where pj are primes. This result is as good as what one can obtain from the generalized Riemann hypothesis.
基金the National Natural Science Foundation of China(project No.52166004)Yunnan Major Scientific and Technological Projects(grant No.202202AG050002)+2 种基金Scientific Research Fund Project of Yunnan Education Department,China(grant No.2021j0063)Natural Science FoundationofYunnan Province,China(grant No.202101AU070031)the teaching projects A Quality Course for Graduate Students in Yunnan Province"Numerical Analysis","Advanced Mathematics Teaching Team of Engineering Subjects of Kunming University of Science and Technology".
文摘The present study proposes a novel method based on the geometric theory for measuring the distribution of bubble swarms in the circular region of a direct-contact heat exchanger.It was determined that the mixing is uniform when the average distance between the bubble swarms in the unit circular region is approximately 0.9054,which is the standard reference value.The effect of sample size(i.e.,the number of bubbles)on mixing uniformity was investigated to determine the optimal sample size.It was verified that the metric's accuracy and stability were higher with a sample size of 155.Accordingly,it was proposed to increase the sample size by filling irregular bubbles using a segmentation method,which enabled a further accurate assessment of the mixing uniformity.The mixing uniformity of bubble swarms in the circular region and its maximum internal connection with the square region was accurately quantified.It was revealed that the relative average error increased by approximately 3.47% due to information loss.The proposed method was demonstrated to be rotationally invariant.The present study provided novel insights into evaluating mixing uniformity,which would guide enhanced heat transfer and the effective evaluation of the spatiotemporal characteristics of transient mixing in circular regions or the cross-sections of chemical transport pipelines.
