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Engineering the spectra of photon triplets generated from micro/nanofiber
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作者 瞿川 郭东琴 +4 位作者 李笑笑 刘振旗 赵义 张胜海 卫正统 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期408-414,共7页
Quantum light sources are the core resources for photonics-based quantum information processing.We investigate the spectral engineering of photon triplets generated by third-order spontaneous parametric down-conversio... Quantum light sources are the core resources for photonics-based quantum information processing.We investigate the spectral engineering of photon triplets generated by third-order spontaneous parametric down-conversion in micro/nanofiber.The phase mismatching at one-third pump frequency gives rise to non-degenerate photon triplets,the joint spectral intensity of which has an elliptical locus with a fixed eccentricity of√6/3.Therefore,we propose a frequency-division scheme to separate non-degenerate photon triplets into three channels with high heralding efficiency for the first time.Choosing an appropriate pump wavelength can compensate for the fabrication errors of micro/nanofiber and also generate narrowband,non-degenerate photon triplet sources with a high signal-to-noise ratio.Furthermore,the long-period micro/nanofiber grating introduces a new controllable degree of freedom to tailor phase matching,resulting from the periodic oscillation of dispersion.In this scheme,the wavelength of photon triplets can be flexibly tuned using quasi-phase matching.We study the generation of photon triplets from this novel perspective of spectrum engineering,and we believe that this work will accelerate the practical implementation of photon triplets in quantum information processing. 展开更多
关键词 photon triplets micro/nanofiber spectrum engineering
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Properties,combustion behavior,and kinetic triplets of coke produced by low-temperature oxidation and pyrolysis:Implications for heavy oil in-situ combustion 被引量:4
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作者 Shuai Zhao Wan-Fen Pu +6 位作者 Lei Su Ce Shang Yang Song Wei Li Hui-Zhuo He Yi-Gang Liu Zhe-Zhi Liu 《Petroleum Science》 SCIE CAS CSCD 2021年第5期1483-1491,共9页
This work aimed at investigating the crucial factor in building and maintaining the combustion front during in-situ combustion(ISC),oxidized coke and pyrolyzed coke.The surface morphologies,elemental contents,and non-... This work aimed at investigating the crucial factor in building and maintaining the combustion front during in-situ combustion(ISC),oxidized coke and pyrolyzed coke.The surface morphologies,elemental contents,and non-isothermal mass losses of the oxidized and pyrolyzed cokes were thoroughly examined.The results indicated that the oxidized coke could be combusted at a lower temperature compared to the pyrolyzed coke due primarily to their differences in the molecular polarity and microstructure.Kinetic triplets of coke combustion were determined using iso-conversional models and one advanced integral master plots method.The activation energy values of the oxidized and pyrolyzed cokes varied in the range of 130-153 k J/mol and 95-120 kJ/mol,respectively.The most appropriate reaction model of combustion of the oxidized and pyrolyzed cokes followed three-dimensional diffusion model(D_(3)) and random nucleation and subsequent growth model(F_(1)),respectively.These observations assisted in building the numerical model of these two types of cokes to simulate the ISC process. 展开更多
关键词 Oxidized coke Pyrolyzed coke Heavy oil In-situ combustion Kinetic triplets
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Vortex pinning and rectification effect in a nanostructured superconducting film with a square array of antidot triplets 被引量:1
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作者 An He Cun Xue Youhe Zhou 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第5期458-463,共6页
We study the stability of vortices pinning and dynamics in a superconducting thin strip containing a square array of antidot triplets by using the nonlinear Ginzburg–Landau(GL)theory.Compared with the regular square ... We study the stability of vortices pinning and dynamics in a superconducting thin strip containing a square array of antidot triplets by using the nonlinear Ginzburg–Landau(GL)theory.Compared with the regular square array of circular holes,the vortices are no longer pinned inside the circular holes,but instead stabilized at the center of the antidot triplets depending on the geometry parameters.Moreover,the influences of the geometry parameters and the polarity of the applied current on the current–voltage(I–V)characteristics are also studied.The critical current for the sample turning into a normal state becomes smaller when the hole diameter D is smaller and the spacing B between the holes is larger.Due to the asymmetric pinning sites,our numerical simulations demonstrate that the positive and negative rectified voltages appear alternately in the resistive state of the sample under an ac current of square pulses. 展开更多
关键词 matching effect antidot triplets current-voltage characteristic critical current
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PROBE FOR THE FORMATION RATIO BETWEEN EXCITED TRIPLETS AND SINGLETS AS GENERATED IN POLYMER LIGHT-EMITTING DIODES
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作者 Jing-ying Zhang Shi-dong Kan +1 位作者 Yu-guang Ma Jia-cong Shen Key Lab for Supramolecular Structure and Spectroscopy of Ministry of Education, Jilin University Changchun 130023, China 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2001年第6期591-596,共6页
The electroluminescence (EL) produced by a highly luminescent phosphorescent dye Cu-4(CdropCPh)(4)L-2 (L = 1.8-bis(di-phenylphosphino)-3,6-dioxaoctane, Cu-4) doped polymer as emitting layer is reported. The effects of... The electroluminescence (EL) produced by a highly luminescent phosphorescent dye Cu-4(CdropCPh)(4)L-2 (L = 1.8-bis(di-phenylphosphino)-3,6-dioxaoctane, Cu-4) doped polymer as emitting layer is reported. The effects of the charge injection balance on the polymers, in particular, poly(N-vinylcarbazole) (PVK) have been studied by using photoluminescence and electroluminescence spectroscopy. Changes in the emission spectra demonstrate the influence of the charge injection balance on the formation ratio of triplet and singlet excitons. This provides a new technical approach to realize the color patterning in polymer LEDs. 展开更多
关键词 ELECTROLUMINESCENCE organic polymer triplet exciton
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Primality Testing Using Complex Integers and Pythagorean Triplets
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作者 Boris Verkhovsky 《International Journal of Communications, Network and System Sciences》 2012年第9期513-519,共7页
Prime integers and their generalizations play important roles in protocols for secure transmission of information via open channels of telecommunication networks. Generation of multidigit large primes in the design st... Prime integers and their generalizations play important roles in protocols for secure transmission of information via open channels of telecommunication networks. Generation of multidigit large primes in the design stage of a cryptographic system is a formidable task. Fermat primality checking is one of the simplest of all tests. Unfortunately, there are composite integers (called Carmichael numbers) that are not detectable by the Fermat test. In this paper we consider modular arithmetic based on complex integers;and provide several tests that verify the primality of real integers. Although the new tests detect most Carmichael numbers, there are a small percentage of them that escape these tests. 展开更多
关键词 CRYPTOSYSTEM Design PRIMALITY Testing Fermat Test PYTHAGOREAN TRIPLET Strong Carmichael Number QUATERNIONS
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Energy-Transfer in CsPbBr_(3)Nanocrystals:Sensitization of Porphyrin Triplets
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作者 Yinjie Lu Zongwei Chen 《Chinese Journal of Chemical Physics》 SCIE EI CAS 2024年第5期632-637,I0059-I0062,I0100,共11页
Sensitizing molecular triplets by colloidal nanocrystals via triplet energy transfer is important for applications such as upconversion or organic synthesis.Typically two step triplet energy transfer(TET)are included ... Sensitizing molecular triplets by colloidal nanocrystals via triplet energy transfer is important for applications such as upconversion or organic synthesis.Typically two step triplet energy transfer(TET)are included in these applications:firstly the triplet energy stored in nanocrystals are extracted into surface ligands,and then the ligands further transfer triplet energy into molecules in bulk solution.Here we report one-step TET application from CsPbBr_(3)perovskite nanocrystals(NCs)to surface-anchored metalloporphyrin derivative molecules(MP).Compared to conventional two-step TET,the one-step TET mechanism possess lower energy loss and higher TET efficiency which is more generally implementable.In this scheme,photoexcitation of CsPbBr_(3)NCs leads to the sensitization of MP ligands triplets which efficiently emit phosphorescence.The enhanced light absorption of MP ligands and down-shifted photon emission can be useful in devices such as luminescent solar concentrators. 展开更多
关键词 Triplet energy transfer CsPbBr_(3)nanocrystal Metalloporphyrin derivative Luminescent solar concentrators
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基于改进YOLOv8n的煤矿井下钻杆计数方法
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作者 姜媛媛 刘宋波 《工矿自动化》 CSCD 北大核心 2024年第8期112-119,共8页
为提高煤矿井下钻杆计数的效率和精度,提出了一种基于改进YOLOv8n模型的煤矿井下钻杆计数方法。建立了YOLOv8n−TBiD模型,该模型可准确检测矿井钻机工作视频中的钻杆并进行有效分割:为有效捕获钻杆的边界信息,提高模型对钻杆形状识别的精... 为提高煤矿井下钻杆计数的效率和精度,提出了一种基于改进YOLOv8n模型的煤矿井下钻杆计数方法。建立了YOLOv8n−TBiD模型,该模型可准确检测矿井钻机工作视频中的钻杆并进行有效分割:为有效捕获钻杆的边界信息,提高模型对钻杆形状识别的精度,使用加权双向特征金字塔网络(BiFPN)替换路径聚合网络(PANet);针对钻杆易与昏暗的矿井环境混淆的问题,在Backbone网络的SPPF模块后添加三分支注意力(Triplet Attention),以增强模型抑制背景干扰的能力;针对钻杆在图像中占比小、背景信息繁杂的问题,采用Dice损失函数替换CIoU损失函数来优化模型对目标钻杆的分割处理。利用YOLOv8n−TBiD模型分割出的钻杆及其掩码信息,根据打钻过程中钻杆掩码面积变小而装新钻杆时钻杆掩码面积突然增大的规律,设计了一种钻杆计数算法。选取综采工作面实际采集的钻机工作视频对基于YOLOv8n−TBiD模型的钻杆计数方法进行了实验验证,结果表明:①YOLOv8n−TBiD模型检测钻杆的平均精度均值达94.9%,与对比模型GCI−YOLOv4,ECO−HC,P−MobileNetV2,YOLOv5,YOLOX相比,检测准确率分别提升了4.3%,7.5%,2.1%,6.3%,5.8%,检测速度较原始YOLOv8n模型提升了17.8%。②所提钻杆计数算法在不同煤矿井下环境的视频数据集上实现了99.3%的钻杆计数精度。 展开更多
关键词 矿井钻机 钻杆计数 YOLOv8n−TBiD BiFPN Triplet Attention Dice损失函数 钻杆掩码 图像分割
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Fermat and Pythagoras Divisors for a New Explicit Proof of Fermat’s Theorem:a4 + b4 = c4. Part I
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作者 Prosper Kouadio Kimou François Emmanuel Tanoé Kouassi Vincent Kouakou 《Advances in Pure Mathematics》 2024年第4期303-319,共17页
In this paper we prove in a new way, the well known result, that Fermat’s equation a<sup>4</sup> + b<sup>4</sup> = c<sup>4</sup>, is not solvable in ℕ , when abc≠0 . To show this ... In this paper we prove in a new way, the well known result, that Fermat’s equation a<sup>4</sup> + b<sup>4</sup> = c<sup>4</sup>, is not solvable in ℕ , when abc≠0 . To show this result, it suffices to prove that: ( F 0 ): a 1 4 + ( 2 s b 1 ) 4 = c 1 4 , is not solvable in ℕ , (where a 1 , b 1 , c 1 ∈2ℕ+1 , pairwise primes, with necessarly 2≤s∈ℕ ). The key idea of our proof is to show that if (F<sub>0</sub>) holds, then there exist α 2 , β 2 , γ 2 ∈2ℕ+1 , such that ( F 1 ): α 2 4 + ( 2 s−1 β 2 ) 4 = γ 2 4 , holds too. From where, one conclude that it is not possible, because if we choose the quantity 2 ≤ s, as minimal in value among all the solutions of ( F 0 ) , then ( α 2 ,2 s−1 β 2 , γ 2 ) is also a solution of Fermat’s type, but with 2≤s−1<s , witch is absurd. To reach such a result, we suppose first that (F<sub>0</sub>) is solvable in ( a 1 ,2 s b 1 , c 1 ) , s ≥ 2 like above;afterwards, proceeding with “Pythagorician divisors”, we creat the notions of “Fermat’s b-absolute divisors”: ( d b , d ′ b ) which it uses hereafter. Then to conclude our proof, we establish the following main theorem: there is an equivalence between (i) and (ii): (i) (F<sub>0</sub>): a 1 4 + ( 2 s b 1 ) 4 = c 1 4 , is solvable in ℕ , with 2≤s∈ℕ , ( a 1 , b 1 , c 1 )∈ ( 2ℕ+1 ) 3 , coprime in pairs. (ii) ∃( a 1 , b 1 , c 1 )∈ ( 2ℕ+1 ) 3 , coprime in pairs, for wich: ∃( b ′ 2 , b 2 , b ″ 2 )∈ ( 2ℕ+1 ) 3 coprime in pairs, and 2≤s∈ℕ , checking b 1 = b ′ 2 b 2 b ″ 2 , and such that for notations: S=s−λ( s−1 ) , with λ∈{ 0,1 } defined by c 1 − a 1 2 ≡λ( mod2 ) , d b =gcd( 2 s b 1 , c 1 − a 1 )= 2 S b 2 and d ′ b = 2 s−S b ′ 2 = 2 s B 2 d b , where ( 2 s B 2 ) 2 =gcd( b 1 2 , c 1 2 − a 1 2 ) , the following system is checked: { c 1 − a 1 = d b 4 2 2+λ = 2 2−λ ( 2 S−1 b 2 ) 4 c 1 + a 1 = 2 1+λ d ′ b 4 = 2 1+λ ( 2 s−S b ′ 2 ) 4 c 1 2 + a 1 2 =2 b ″ 2 4;and this system implies: ( b 1−λ,2 4 ) 2 + ( 2 4s−3 b λ,2 4 ) 2 = ( b ″ 2 2 ) 2;where: ( b 1−λ,2 , b λ,2 , b ″ 2 )={ ( b ′ 2 , b 2 , b ″ 2 )  if λ=0 ( b 2 , b ′ 2 , b ″ 2 )  if λ=1;From where, it is quite easy to conclude, following the method explained above, and which thus closes, part I, of this article. . 展开更多
关键词 Factorisation in Greatest Common Divisor Pythagoras Equation Pythagorician triplets Fermat's Equations Pythagorician Divisors Fermat's Divisors Diophantine Equations of Degree 2 4-Integral Closure of in
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A New Proof for Congruent Number’s Problem via Pythagorician Divisors
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作者 Léopold Dèkpassi Keuméan François Emmanuel Tanoé 《Advances in Pure Mathematics》 2024年第4期283-302,共20页
Considering Pythagorician divisors theory which leads to a new parameterization, for Pythagorician triplets ( a,b,c )∈ ℕ 3∗ , we give a new proof of the well-known problem of these particular squareless numbers n∈ ℕ... Considering Pythagorician divisors theory which leads to a new parameterization, for Pythagorician triplets ( a,b,c )∈ ℕ 3∗ , we give a new proof of the well-known problem of these particular squareless numbers n∈ ℕ ∗ , called congruent numbers, characterized by the fact that there exists a right-angled triangle with rational sides: ( A α ) 2 + ( B β ) 2 = ( C γ ) 2 , such that its area Δ= 1 2 A α B β =n;or in an equivalent way, to that of the existence of numbers U 2 , V 2 , W 2 ∈ ℚ 2∗ that are in an arithmetic progression of reason n;Problem equivalent to the existence of: ( a,b,c )∈ ℕ 3∗ prime in pairs, and f∈ ℕ ∗ , such that: ( a−b 2f ) 2 , ( c 2f ) 2 , ( a+b 2f ) 2 are in an arithmetic progression of reason n;And this problem is also equivalent to that of the existence of a non-trivial primitive integer right-angled triangle: a 2 + b 2 = c 2 , such that its area Δ= 1 2 ab=n f 2 , where f∈ ℕ ∗ , and this last equation can be written as follows, when using Pythagorician divisors: (1) Δ= 1 2 ab= 2 S−1 d e ¯ ( d+ 2 S−1 e ¯ )( d+ 2 S e ¯ )=n f 2;Where ( d, e ¯ )∈ ( 2ℕ+1 ) 2 such that gcd( d, e ¯ )=1 and S∈ ℕ ∗ , where 2 S−1 , d, e ¯ , d+ 2 S−1 e ¯ , d+ 2 S e ¯ , are pairwise prime quantities (these parameters are coming from Pythagorician divisors). When n=1 , it is the case of the famous impossible problem of the integer right-angled triangle area to be a square, solved by Fermat at his time, by his famous method of infinite descent. We propose in this article a new direct proof for the numbers n=1 (resp. n=2 ) to be non-congruent numbers, based on an particular induction method of resolution of Equation (1) (note that this method is efficient too for general case of prime numbers n=p≡a ( ( mod8 ) , gcd( a,8 )=1 ). To prove it, we use a classical proof by induction on k , that shows the non-solvability property of any of the following systems ( t=0 , corresponding to case n=1 (resp. t=1 , corresponding to case n=2 )): ( Ξ t,k ){ X 2 + 2 t ( 2 k Y ) 2 = Z 2 X 2 + 2 t+1 ( 2 k Y ) 2 = T 2 , where k∈ℕ;and solutions ( X,Y,Z,T )=( D k , E k , f k , f ′ k )∈ ( 2ℕ+1 ) 4 , are given in pairwise prime numbers.2020-Mathematics Subject Classification 11A05-11A07-11A41-11A51-11D09-11D25-11D41-11D72-11D79-11E25 . 展开更多
关键词 Prime Numbers-Diophantine Equations of Degree 2 & 4 Factorization Greater Common Divisor Pythagoras Equation Pythagorician triplets Congruent Numbers Inductive Demonstration Method Infinite Descent BSD Conjecture
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基于HGTC−YOLOv8n模型的煤矸识别算法研究 被引量:1
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作者 滕文想 王成 费树辉 《工矿自动化》 CSCD 北大核心 2024年第5期52-59,共8页
现有基于深度学习的煤矸识别方法在煤矿井下低照度、高噪声及运动模糊等复杂工况下存在煤矸识别精度低、小目标煤矸容易漏检、模型参数量和运算量大,难以部署到计算资源有限的设备中等问题,提出了一种基于HGTC−YOLOv8n模型的煤矸识别算... 现有基于深度学习的煤矸识别方法在煤矿井下低照度、高噪声及运动模糊等复杂工况下存在煤矸识别精度低、小目标煤矸容易漏检、模型参数量和运算量大,难以部署到计算资源有限的设备中等问题,提出了一种基于HGTC−YOLOv8n模型的煤矸识别算法。采用HGNetv2网络替换YOLOv8n的主干网络,通过多尺度特征的有效提取,提高煤矸识别效果并减少模型的存储需求和计算资源消耗;在主干网络中嵌入三重注意力机制模块Triplet Attention,捕获不同维度间的交互信息,增强煤矸图像目标特征的提取,减少无关信息的干扰;选用内容感知特征重组模块(CARAFE)来改进YOLOv8n颈部特征融合网络上采样算子,利用上下文信息提高感受视野,提高小目标煤矸识别准确率。实验结果表明:①HGTC−YOLOv8n模型的平均精度均值为93.5%,模型的参数量为2.645×10^(6),浮点运算量为8.0×10^(9),帧速率为79.36帧/s。②平均精度均值较YOLOv8n模型提升了2.5%,参数量和浮点运算量较YOLOv8n模型分别下降了16.22%和10.11%。③与YOLO系列模型相比,HGTC−YOLOv8n模型的平均精度均值最高,且参数量和浮点运算量最少,检测速度较快,综合检测性能最佳。④基于HGTC−YOLOv8n模型的煤矸识别算法在煤矿井下复杂工况下,改善了煤矸识别精度低、小目标煤矸容易漏检等问题,满足煤矸图像实时检测要求。 展开更多
关键词 煤矸识别 小目标识别 YOLOv8n 内容感知特征重组模块 三重注意力机制 Triplet Attention HGNetv2
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基于上下文语义联合YOLOv7的分心驾驶检测算法 被引量:1
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作者 李富 徐凯 +2 位作者 朱灵龙 沈昊君 王泉 《国外电子测量技术》 2024年第3期121-128,共8页
针对分心驾驶检测方法存在实时性差、精度低、可部署性差的问题,提出了一种基于上下文语义增强联合YOLOv7的分心驾驶检测算法。首先将模型backbone和head部分的ELAN模块替换成语义上下文增强模块(contextual transformer,CoT),提高上下... 针对分心驾驶检测方法存在实时性差、精度低、可部署性差的问题,提出了一种基于上下文语义增强联合YOLOv7的分心驾驶检测算法。首先将模型backbone和head部分的ELAN模块替换成语义上下文增强模块(contextual transformer,CoT),提高上下文语义信息的捕获能力。其次,将语义关联增强机制(triplet attention)融入卷积块中,插入backbone和head的连接头之间以及融合MP2模块,强化目标间的关联关系以及提升目标特征提取能力。最后,将自注意力双向Transformer模块(Biformer)模块融合SPPCSPC模块,提升模型对分心驾驶中的复杂场景和遮挡目标的处理能力。改进的YOLOv7算法在分心驾驶数据集下平均精度均值(mean average precision,mAP)达到了87.3%,比原算法提高了4.3%,模型参数量减少了4.7%,每秒传输帧数达到了90 fps,具有较好的检测精度与速度。 展开更多
关键词 YOLOv7 分心驾驶检测 COT Biformer Triplet Attention
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基于注意力机制的多尺度手部分割方法
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作者 周雯晴 代素敏 +1 位作者 王阳萍 王文润 《液晶与显示》 CAS CSCD 北大核心 2024年第11期1506-1518,共13页
针对手部边缘细节信息分割不精确及小面积手部的错检、漏检问题,提出一种基于注意力机制的多尺度手部分割方法。首先,对Transformer模块重新进行设计优化,提出窗口自注意力结构和双分支前馈神经网络(Dual-branch FeedForward Networks,D... 针对手部边缘细节信息分割不精确及小面积手部的错检、漏检问题,提出一种基于注意力机制的多尺度手部分割方法。首先,对Transformer模块重新进行设计优化,提出窗口自注意力结构和双分支前馈神经网络(Dual-branch FeedForward Networks,D-FFN)机制,通过窗口自注意力机制整合全局和局部的依赖信息,D-FFN抑制背景信息的干扰;然后,提出一种结合条形池化和级联网络的多尺度特征提取模块增大感受野,提高手部分割模型的准确性和鲁棒性;最后,提出基于Triplet Attention机制的上采样解码器模块,通过调节通道维度与空间维度的注意力权重将目标特征和背景的冗余特征区分开。将所提算法在公开数据集GTEA(Georgia Tech Egocentric Activity)和EYTH(EgoYouTubeHands)上测试,实验结果表明,该算法在两个数据集上的平均交并比(MIoU)值分别达到了95.8%和90.2%,相较于TransUnet算法分别提升了2.5%和2.1%,满足手部图像分割的稳定可靠、精度高、抗干扰能力强等要求。 展开更多
关键词 手部分割 深度学习 TransUnet 前馈神经网络 空洞空间金字塔池化模块 Triplet Attention
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Broadband Visible Light Harvesting BODIPY-Perylene Dyad and Triad:Synthesis,Photophysical Properties,and Photooxidation Applications
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作者 Yu Gong Lei Dong +7 位作者 Qiang-Qiang Shen Meng Li Yi-Nuo Gu Wei-Guang Zhang Xin-Yu Xue Qing-Jin Xue San-E Zhu Yu-Mei Zhou 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2024年第4期545-552,I0067-I0079,I0094,I0095,共23页
In this study,diodo boron dipyrromethene(BODIPY)is employed a8 the energy donor and 3,4,9,10-perylene tetracarboxylic dianhydride(PDA)as the energy acceptor,enabling the synthesis of two new compounds:a BODIPY-perylen... In this study,diodo boron dipyrromethene(BODIPY)is employed a8 the energy donor and 3,4,9,10-perylene tetracarboxylic dianhydride(PDA)as the energy acceptor,enabling the synthesis of two new compounds:a BODIPY-perylene dyad named P1,and a triad named P2.To investigate the impact of the energy donor on the photophysical processes of the system,P1 comprises one diodo-BODIPY unit and one PDA unit,whereas P2 contains two diodo-BODIPY moieties and one PDA unit.Due to the good spectral complementarity between diiodo-BODIPY and PDA,these two compounds exhibit excellent light-harvesting capabilities in the 400-620 nm range.Steady-state fluorescence spectra demonstrate that when preferentially exciting the diodo-BODIPY moiety,it can effectively transfer energy to PDA;when selectively exciting the PDA moiety,quenching of PDA fluorescence is observed in both P1 and P2.Nanosecond transient absorption results show that both compounds can efficiently generate triplet excited states,which are located on the PDA part.The lifetimes of the triplet states for these two compounds are 103 and 89μs,respectively,significantly longer than that of diiodo-BODIPY.The results from the photooxidation experiments reveal that both P1 and P2 demonstrate good photostability and photooxidation capabilities,with P2 showing superior photooxidative efficiency.The photooxidation rate constant for P2 is 1.3 times that of P1,and its singlet oxygen quantum yield is 1.6 times that of P1.The results obtained here offer valuable insights for designing new photosensitizers. 展开更多
关键词 BODIPY PERYLENE Triplet excited states Nanosecond transient absorption PHOTOOXIDATION
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Improved multi-scale inverse bottleneck residual network based on triplet parallel attention for apple leaf disease identification
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作者 Lei Tang Jizheng Yi Xiaoyao Li 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第3期901-922,共22页
Accurate diagnosis of apple leaf diseases is crucial for improving the quality of apple production and promoting the development of the apple industry. However, apple leaf diseases do not differ significantly from ima... Accurate diagnosis of apple leaf diseases is crucial for improving the quality of apple production and promoting the development of the apple industry. However, apple leaf diseases do not differ significantly from image texture and structural information. The difficulties in disease feature extraction in complex backgrounds slow the related research progress. To address the problems, this paper proposes an improved multi-scale inverse bottleneck residual network model based on a triplet parallel attention mechanism, which is built upon ResNet-50, while improving and combining the inception module and ResNext inverse bottleneck blocks, to recognize seven types of apple leaf(including six diseases of alternaria leaf spot, brown spot, grey spot, mosaic, rust, scab, and one healthy). First, the 3×3 convolutions in some of the residual modules are replaced by multi-scale residual convolutions, the convolution kernels of different sizes contained in each branch of the multi-scale convolution are applied to extract feature maps of different sizes, and the outputs of these branches are multi-scale fused by summing to enrich the output features of the images. Second, the global layer-wise dynamic coordinated inverse bottleneck structure is used to reduce the network feature loss. The inverse bottleneck structure makes the image information less lossy when transforming from different dimensional feature spaces. The fusion of multi-scale and layer-wise dynamic coordinated inverse bottlenecks makes the model effectively balances computational efficiency and feature representation capability, and more robust with a combination of horizontal and vertical features in the fine identification of apple leaf diseases. Finally, after each improved module, a triplet parallel attention module is integrated with cross-dimensional interactions among channels through rotations and residual transformations, which improves the parallel search efficiency of important features and the recognition rate of the network with relatively small computational costs while the dimensional dependencies are improved. To verify the validity of the model in this paper, we uniformly enhance apple leaf disease images screened from the public data sets of Plant Village, Baidu Flying Paddle, and the Internet. The final processed image count is 14,000. The ablation study, pre-processing comparison, and method comparison are conducted on the processed datasets. The experimental results demonstrate that the proposed method reaches 98.73% accuracy on the adopted datasets, which is 1.82% higher than the classical ResNet-50 model, and 0.29% better than the apple leaf disease datasets before preprocessing. It also achieves competitive results in apple leaf disease identification compared to some state-ofthe-art methods. 展开更多
关键词 multi-scale module inverse bottleneck structure triplet parallel attention apple leaf disease
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COMPREHENSIVE STUDY OF TWO SETS OF TRIPLETS
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作者 杨汉民 马慰国 +5 位作者 林田 赵叔鑫 胡炳蔚 杜耀仁 李生斌 李小莉 《Chinese Science Bulletin》 SCIE EI CAS 1989年第19期1643-1647,共5页
Triplets are seldom and monozygotic triplets are scarcely seen in humanity. There are few reports on triplets at home and abroad and diagnosis of zygosity is rarely made. We did the analysis of clinical material on tw... Triplets are seldom and monozygotic triplets are scarcely seen in humanity. There are few reports on triplets at home and abroad and diagnosis of zygosity is rarely made. We did the analysis of clinical material on two sets of triplets. Diagnosis and analysis of zygosity were made in eleven ways about 57 items including blood type and RBC enzyme type, etc. 展开更多
关键词 multiple PREGNANCY triplets ZYGOSITY DIAGNOSIS HEREDITARY
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Lanthanide nanoparticles ignite dark molecular triplets 被引量:1
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作者 Jin Xu Xueyuan Chen 《Science China Chemistry》 SCIE EI CAS CSCD 2021年第4期511-512,共2页
Molecular triplets have attracted great interest across multidisciplinary fields of the research ranging from thermally activated delayed fluorescence[1],triplet-triplet annihilation(TTA)upconversion[2],to photodynami... Molecular triplets have attracted great interest across multidisciplinary fields of the research ranging from thermally activated delayed fluorescence[1],triplet-triplet annihilation(TTA)upconversion[2],to photodynamic therapy relying on TTA between triplet photosensitizers and surrounding triplet oxygen to generate singlet oxygen species[3]. 展开更多
关键词 TRIPLET LANTHANIDE ANNIHILATION
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基于Gram矩阵的T-CNN时间序列分类方法 被引量:2
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作者 王俊陆 李素 +2 位作者 纪婉婷 姜天 宋宝燕 《浙江大学学报(工学版)》 EI CAS CSCD 北大核心 2023年第2期267-276,共10页
时间序列分类是流式数据事件分析和数据挖掘的基础.针对现有方法损失时间属性、分类准确率低、效率低等问题,提出基于Gram矩阵的T-CNN时间序列分类方法.该方法对时间序列进行小波阈值去噪,过滤正态曲线噪声,提出基于Gram矩阵的无损时间... 时间序列分类是流式数据事件分析和数据挖掘的基础.针对现有方法损失时间属性、分类准确率低、效率低等问题,提出基于Gram矩阵的T-CNN时间序列分类方法.该方法对时间序列进行小波阈值去噪,过滤正态曲线噪声,提出基于Gram矩阵的无损时间域图像转换方法,保留事件全部信息.改进时间序列CNN分类方法,在卷积层计算引入Toeplitz卷积核矩阵,实现矩阵乘积替换卷积运算.引入Triplet网络思想,构建T-CNN分类模型,通过计算同类事件与不同类事件间的相似度优化CNN的平方损失函数,提高T-CNN模型梯度下降的收敛速率及分类准确性.实验表明,相比现有方法,T-CNN时间序列分类方法能够提高35%的分类准确率、35%的分类精确率及40%的分类效率. 展开更多
关键词 GRAM矩阵 T-CNN模型 TOEPLITZ 损失函数 Triplet网络
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Pythagorician Divisors and Applications to Some Diophantine Equations
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作者 François Emmanuel Tanoé Prosper Kouadio Kimou 《Advances in Pure Mathematics》 2023年第2期35-70,共36页
We consider the Pythagoras equation X<sup>2</sup> +Y<sup>2</sup> = Z<sup>2</sup>, and for any solution of the type (a,b = 2<sup>s</sup>b<sub>1 </sub>≠0,c) ... We consider the Pythagoras equation X<sup>2</sup> +Y<sup>2</sup> = Z<sup>2</sup>, and for any solution of the type (a,b = 2<sup>s</sup>b<sub>1 </sub>≠0,c) ∈ N<sup>*3</sup>, s ≥ 2, b<sub>1</sub>odd, (a,b,c) ≡ (±1,0,1)(mod 4), c > a , c > b, and gcd(a,b,c) = 1, we then prove the Pythagorician divisors Theorem, which results in the following: , where (d,d′′) (resp. (e,e<sup>n</sup>)) are unique particular divisors of a and b, such that a = dd′′ (resp. b = ee′′ ), these divisors are called: Pythagorician divisors from a, (resp. from b). Let’s put λ ∈{0,1}, defined by: and S = s -λ (s -1). Then such that . Moreover the map is a bijection. We apply this new tool to obtain a new classification of the primitive, positive and non-trivial solutions of the Pythagoras equations: a<sup>2</sup> + b<sup>2</sup> = c<sup>2</sup> via the Pythagorician parameters (d,e,S ). We obtain for (d, e) fixed, the equivalence class of any Pythagorician solution (a,b,c), checking , namely: . We also update the solutions of some Diophantine equations of degree 2, already known, but very important for the resolution of other equations. With this tool of Pythagorean divisors, we have obtained (in another paper) new recurrent methods to solve Fermat’s equation: a<sup>4</sup> + b<sup>4 </sup>= c<sup>4</sup>, other than usual infinite descent method;and to solve congruent numbers problem. We believe that this tool can bring new arguments, for Diophantine resolution, of the general equations of Fermat: a<sup>2p</sup> + b<sup>2p</sup> = c<sup>2p</sup> and a<sup>p</sup> + b<sup>p</sup> = c<sup>p</sup>. MSC2020-Mathematical Sciences Classification System: 11A05-11A51-11D25-11D41-11D72. 展开更多
关键词 Pythagoras Equation Pythagorician triplets Diophantine Equations of Degree 2 Factorisation-Gcd-Fermat’s Equations
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Diophantine Quotients and Remainders with Applications to Fermat and Pythagorean Equations
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作者 Prosper Kouadio Kimou François Emmanuel Tanoé 《American Journal of Computational Mathematics》 2023年第1期199-210,共12页
Diophantine equations have always fascinated mathematicians about existence, finitude, and the calculation of possible solutions. Among these equations, one of them will be the object of our research. This is the Pyth... Diophantine equations have always fascinated mathematicians about existence, finitude, and the calculation of possible solutions. Among these equations, one of them will be the object of our research. This is the Pythagoras’- Fermat’s equation defined as follows.                                                                                         (1) when , it is well known that this equation has an infinity of solutions but has none (non-trivial) when . We also know that the last result, named Fermat-Wiles theorem (or FLT) was obtained at great expense and its understanding remains out of reach even for a good fringe of professional mathematicians. The aim of this research is to set up new simple but effective tools in the treatment of Diophantine equations and that of Pythagoras-Fermat. The tools put forward in this research are the properties of the quotients and the Diophantine remainders which we define as follows. Let a non-trivial triplet () solution of Equation (1) such that . and are called the Diophantine quotients and remainders of solution . We compute the remainder and the quotient of b and c by a using the division algorithm. Hence, we have: and et with . We prove the following important results. if and only if and if and only if . Also, we deduce that or for any hypothetical solution . We illustrate these results by effectively computing the Diophantine quotients and remainders in the case of Pythagorean triplets using a Python program. In the end, we apply the previous properties to directly prove a partial result of FLT. . 展开更多
关键词 Diophantine Equation Modular Arithmetic Fermat-Wiles Theorem Pythagorean triplets Division Theorem Division Algorithm Python Program Diophantine Quotients Diophantine Remainders
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改进的EfficientDet及直方图均衡化的工件检测算法研究 被引量:1
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作者 石林坤 田怀文 杨玉洁 《机械科学与技术》 CSCD 北大核心 2023年第9期1445-1454,共10页
针对流水线加工作业环境下工业机器人对工件检测及定位率较低,速度慢等问题,提出基于改进的EfficientDet工件检测神经网络模型。采用EfficientNet作为主干特征提取网络,利用Triplet Attention注意力机制代替原始的SE Attention机制,同... 针对流水线加工作业环境下工业机器人对工件检测及定位率较低,速度慢等问题,提出基于改进的EfficientDet工件检测神经网络模型。采用EfficientNet作为主干特征提取网络,利用Triplet Attention注意力机制代替原始的SE Attention机制,同时借鉴循环特征融合思想,采用Recursive-BiFPN循环特征融合网络结构。针对正负样本不均等问题,采用generalized focal loss改进原始focal loss损失函数。考虑到机械加工特定生产环境,采用直方图均衡化思想对数据进行对比度提高。最后利用工业相机建立自制数据集并进行模型训练,在复杂工业生产情况下,改进后的EfficientDet在mAP上较原始网络提高6.1%,同时速度提高到72帧/s。最后实验结果表明,该算法在生产环境下能快速准确地对工件进行定位检测,为实际生产需要提供新的解决思路。 展开更多
关键词 工件检测 EfficientDet模型 Triplet Attention generalized focal loss
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