Engineering the spectra of photon triplets generated from micro/nanofiber

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.

Energy-Transfer in CsPbBr_(3)Nanocrystals:Sensitization of Porphyrin Triplets

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.

Properties,combustion behavior,and kinetic triplets of coke produced by low-temperature oxidation and pyrolysis:Implications for heavy oil in-situ combustion

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.

Vortex pinning and rectification effect in a nanostructured superconducting film with a square array of antidot triplets

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.

PROBE FOR THE FORMATION RATIO BETWEEN EXCITED TRIPLETS AND SINGLETS AS GENERATED IN POLYMER LIGHT-EMITTING DIODES

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.

Primality Testing Using Complex Integers and Pythagorean Triplets

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.

COMPREHENSIVE STUDY OF TWO SETS OF TRIPLETS

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.

Lanthanide nanoparticles ignite dark molecular triplets

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].

基于改进YOLOv8n的煤矿井下钻杆计数方法

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。

Fermat and Pythagoras Divisors for a New Explicit Proof of Fermat’s Theorem:a4 + b4 = c4. Part I

In this paper we prove in a new way, the well known result, that Fermat’s equation a4 + b4 = c4, 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 (F0) 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−10) 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) (F0): 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. .

A New Proof for Congruent Number’s Problem via Pythagorician Divisors

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 .

基于上下文语义联合YOLOv7的分心驾驶检测算法

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。

基于HGTC−YOLOv8n模型的煤矸识别算法研究

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。

基于注意力机制的多尺度手部分割方法

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。

Improved multi-scale inverse bottleneck residual network based on triplet parallel attention for apple leaf disease identification

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.

基于深度学习的小面积指纹匹配方法

针对传统的基于细节特征点的指纹匹配方法多适用于采集面积较大的指纹,在面向智能手机端的小采集面积指纹时准确率明显下降的问题,提出一种基于深度学习的小面积指纹匹配方法。首先,提取指纹图像的细节特征点信息;其次,搜索和标定感兴趣纹理区域(ROI);然后,构建并改进基于残差结构的轻量级深度神经网络,通过采用二值化特征模式优化网络和Triplet Loss方式训练模型;最后,制定一种智能手机端注册匹配策略实现小面积指纹匹配。实验结果表明,提出方法在公开库FVCDB1与自建数据库上的等错率(EER)分别仅为0.50%与0.58%,远低于传统的基于细节特征点的指纹匹配方法,能够有效提升小面积指纹匹配的性能,更好地满足智能手机端的应用需求。

Energy Transfer Probability Between Host and Guest in Doped Organic Electrophosphorescent Devices

An expression for energy transfer probability （η） between host （TPD） and guest （Ir（ppy）3） phosphorescent systems is proposed,and the energy transfer process in doped organic electrophosphorescent （EP） devices is discussed. The results show that （1） The rate of the triplet energy transfer （KHG and KGH） exponentially increases with the host-guest molecular distance （R）, and KHG decreases quickly as the intermolecular distance of the guest （RGG） increases. In addition,the KHG/KGH ratio of the dopant system increases when R or RGG is reduced; （2） The energy transfer probability approximately linearly decreases as R increases from 0.8 to 1.2nm,and the variation of RGG can be neglected when R〈1.1nm. For 1. 1nm〈R〈l. 2nm, RGG （〈1.6nm） plays an increasingly important role when 71 drops with the latter＇ （3） η increases when the Forster energy transfer rate increases or Gibb＇s energy declines.

Microwave Assisted Synthesis of a New Triplet Iridium（Ⅲ） Pyrazine Complex

A new cyclometalated iridium（IlI） complex Ir（DPP）3 （DPP=2,3-diphenylpyrazine） was prepared by reaction of DPP with iridium trichloride hydrate under microwave irradiation. The structure of the complex was confirmed by elemental analysis, ^1H NMR, and mass spectroscopy. The UV-Vis absorption and photoluminescent properties of the complex were investigated. The complex shows strong ^1MLCT （singlet metal to ligand charge-transfer） and aMLCT （triplet metal to ligand charge-transfer） absorption at 382 and 504 nm, respectively. The complex also shows strong photoluminescence at 573 nm at room temperature. These results suggest the complex to be a promising phosphorescent material.

DISTRIBUTIONS OF TRIPLET CODONS IN MESSENGER RNA SECONDARY STRUCTURES

Analysis of the secondary structures of mRNAs which encode mature peptides shows that the location of each codon in mRNA secondary structure has a trend, which appears to be in agreement with the conformational property of the corresponding amino acid to some extent. Most of the codons that encode hydrophobic amino acids are located in stable stem regions of mRNA secondary structures, and vice versa, most of the codons that encode hydrophilic amino acids are located in flexible loop regions. This result supports the recent conclusion that there may be the information transfer between the three dimensional structures of mRNA and the encoded protein.

基于Gram矩阵的T-CNN时间序列分类方法

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.