Accurate models and nutritional strategies for specific oxidative stress factors: Does the dose matter in swine production?

Oxidative stress has been associated with a number of physiological problems in swine,including reduced production efficiency.Recently,although there has been increased research into regulatory mechanisms and antioxidant strategies in relation to oxidative stress-induced pig production,it remains so far largely unsuccessful to develop accurate models and nutritional strategies for specific oxidative stress factors.Here,we discuss the dose and dose intensity of the causes of oxidative stress involving physiological,environmental and dietary factors,recent research models and the antioxidant strategies to provide theoretical guidance for future oxidative stress research in swine.

Integrated high-performance and accurate shaping technology of low-cost powder metallurgy titanium alloys: A comprehensive review

The practical engineering applications of powder metallurgy (PM) Ti alloys produced through cold compaction and pressure-less sintering are impeded by poor sintering densification, embrittlement caused by excessive O impurities, and severe sintering deforma-tion resulting from the use of heterogeneous powder mixtures. This review presents a summary of our previous work on addressing the above challenges. Initially, we proposed a novel strategy using reaction-induced liquid phases to enhance sintering densification. Near- complete density (relative density exceeding 99%) was achieved by applying the above strategy and newly developed sintering aids. By focusing on the O-induced embrittlement issue, we determined the onset dissolution temperature of oxide films in the Ti matrix. On the basis of this finding, we established a design criterion for effective O scavengers that require reaction with oxide films before their dissol-ution. Consequently, a ductile PM Ti alloy was successfully obtained by introducing 0.3wt% NdB6 as the O scavenger. Lastly, a powder- coating strategy was adopted to address the sintering deformation issue. The ultrafine size and shell-like distribution characteristics of coating particles ensured rapid dissolution and homogeneity in the Ti matrix, thereby facilitating linear shrinkage during sintering. As a result, geometrically complex Ti alloy parts with high dimensional accuracy were fabricated by using the coated powder. Our fundament-al findings and related technical achievements enabled the development of an integrated production technology for the high-performance and accurate shaping of low-cost PM Ti alloys. Additionally, the primary engineering applications and progress in the industrialization practice of our developed technology are introduced in this review.

An adaptive finite-difference method for seismic traveltime modeling based on 3D eikonal equation

3D eikonal equation is a partial differential equation for the calculation of first-arrival traveltimes and has been widely applied in many scopes such as ray tracing,source localization,reflection migration,seismic monitoring and tomographic imaging.In recent years,many advanced methods have been developed to solve the 3D eikonal equation in heterogeneous media.However,there are still challenges for the stable and accurate calculation of first-arrival traveltimes in 3D strongly inhomogeneous media.In this paper,we propose an adaptive finite-difference(AFD)method to numerically solve the 3D eikonal equation.The novel method makes full use of the advantages of different local operators characterizing different seismic wave types to calculate factors and traveltimes,and then the most accurate factor and traveltime are adaptively selected for the convergent updating based on the Fermat principle.Combined with global fast sweeping describing seismic waves propagating along eight directions in 3D media,our novel method can achieve the robust calculation of first-arrival traveltimes with high precision at grid points either near source point or far away from source point even in a velocity model with large and sharp contrasts.Several numerical examples show the good performance of the AFD method,which will be beneficial to many scientific applications.

融合GA-Attention-LSTM算法的温室樱桃环境参数预测与裂果预警

针对温室环境因素对樱桃的影响,设计一套大樱桃温室环境自动监测装置,用来采集温室内的环境参数值为樱桃裂果提供数字化预警支持及防治方案。基于采集的环境参数值,首先使用相关性分析得出与棚内裂果具有强相关性的环境参数特征;其次使用滑动窗口方法将输入的环境特征生成时间序列矩阵形式;随后提出一种融合GA-Attention-LSTM算法的预测模型,实现精准预测棚内的环境参数的功能;最后通过SPSS数据分析软件来分析不同大棚的环境参数和裂果率。所提的融合GA-Attention-LSTM算法的预测模型的平均绝对误差为0.112,均方误差为0.087,相比于LSTM网络模型高出12.80%和9.72%,对环境参数的预测精度更高,同时得出一套科学的樱桃环境参数值范围,为预测模型对樱桃裂果数字化预警提供有力支持。

Analysis of algebraic reconstruction technique for accurate imaging of gas temperature and concentration based on tunable diode laser absorption spectroscopy

An improved algebraic reconstruction technique（ART） combined with tunable diode laser absorption spectroscopy（TDLAS） is presented in this paper for determining two-dimensional（2D） distribution of H2O concentration and temperature in a simulated combustion flame.This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy.It finally proves that reconstruction quality dramatically increases with the number of projection rays increasing until more than 180 for 20 × 20 grid,and after that point,the number of projection rays has little influence on reconstruction accuracy.It is clear that the temperature reconstruction results are more accurate than the water vapor concentration obtained by the traditional concentration calculation method.In the present study an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly is also proposed,and the capability of this new method is evaluated by using appropriate assessment parameters.By using this new approach,not only the concentration reconstruction accuracy is greatly improved,but also a suitable parallel-beam arrangement is put forward for high reconstruction accuracy and simplicity of experimental validation.Finally,a bimodal structure of the combustion region is assumed to demonstrate the robustness and universality of the proposed method.Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable of detecting accurate temperature and concentration profiles.This feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices.

Why Is an Integral an Accurate Value?

The derivative and integral in calculus are both exact values. To explain this reason, the integration interval can be infinitely subdivided. The difference in area between curved trapezoids and rectangles can be explained by the theory of higher-order infinitesimal, leading to the conclusion that the difference between the two is an infinitesimal value. From this, it can be inferred that the result obtained by integration is indeed an accurate value.

New finite strain elastoplastic equations for accurately and explicitly simulating pseudoelastic-to-plastic transition effects of shape memory alloys

A new finite strain elatoplastic J2-flow model with coupling effects of both isotropic and anisotropic hardening is proposed with the co-rotational logarithmic rate.In terms of certain single-variable shape functions representing uniaxial loading and unloading curves,explicit multi-axial expressions for the three hardening quantities incorporated in the new model proposed are derived in unified forms for the purpose of automatically and accurately simulating complex pseudoelastic-to-plastic transition effects of shape memory alloys(SMAs)under multiple loading-unloading cycles.Numerical examples show that with only a single parameter of direct physical meaning for each cycle,accurate and explicit simulations may be achieved for extensive data from multiple cycle tests.

Theory and Practice of High-Level Sprint Training Based on Accurate Sectional Timing

There is an obvious gap in sprint level at home and abroad,and there are different opinions on the reasons.According to the analysis,physical energy and its distribution in each segment are the main factors restricting the sprint performance in China.Different from middle and long-distance running,we must rely on accurate sectional timing technology to master the law of speed-physical energy change in the process of sprint.Each stage is an integral part of the whole dash process,and each part restricts each other.Each stage has a relative best achievement.Simply pursuing the optimal state of segment is not only not helpful to the final result,but also counterproductive.

Analytical Model and Topology Optimization of Doubly-fed Induction Generator

As the core component of energy conversion for large wind turbines,the output performance of doubly-fed induction generators (DFIGs) plays a decisive role in the power quality of wind turbines.To realize the fast and accurate design optimization of DFIGs,this paper proposes a novel hybriddriven surrogate-assisted optimization method.It firstly establishes an accurate subdomain model of DFIGs to analytically predict performance indexes.Furthermore,taking the inexpensive analytical dataset produced by the subdomain model as the source domain and the expensive finite element analysis dataset as the target domain,a high-precision surrogate model is trained in a transfer learning way and used for the subsequent multi-objective optimization process.Based on this model,taking the total harmonic distortion of electromotive force,cogging torque,and iron loss as objectives,and the slot and inner/outer diameters as parameters for optimizing the topology,achieve a rapid and accurate electromagnetic design for DFIGs.Finally,experiments are carried out on a 3MW DFIG to validate the effectiveness of the proposed method.

ACCURATE COMPUTATION AND INTERPOLATION TECHNIQUE OF FINITE ANALYTIC COEFFICIENTS

The finite analytic method (FA) developed in the last decade is an effective numerical method for solving fluid flow problems. However, because of the limitation in the present computer, large round-off errors are found in calculating FA coefficients when Reynolds number is large. This paper investigates the cause of this difficulty and presents a special programming technique in making an accurate computation of FA coefficients. Then a fundamental function known as 'Pe' is tabulated by the accurate computation. In practical application the interpolation technique is employed so that the FA coefficients can be obtained reliably and quickly.

考虑CapsNet算法的未知故障预报应用研究

针对现有故障预报模型自身不具备未知故障识别能力,需重新收集数据对模型进行训练或借助其他组件对未知故障进行学习识别的问题,提出基于CapsNet模型的未知故障预报方法。该方法可有效处理复杂装备的多维状态感知信号,实现装备故障的精确感知,在出现未知故障时可自适应地调整模型并对未知故障进行预报。构建转换矩阵,由低层胶囊的特征预测出相对应的高层特征的存在及姿态。详细介绍了动态路由算法将低层胶囊生成的预测向量整合到对其表示同意的高层胶囊并形成特征向量的过程。在CapsNet最后一层胶囊实现故障特征分类的过程提出阈值判断法,通过合理选择阈值λ的取值范围,使胶囊网络模型能完美地区分已知与未知故障,实现故障的精确预报。使用提出的方法对经过良好训练的系列CapsNets模型进行性能验证。通过实验可以发现,提出的方法能较好地实现未知故障预报,可证实该方法的可行性。

Arbitrary High-Order Fully-Decoupled Numerical Schemes for Phase-Field Models of Two-Phase Incompressible Flows

Due to the coupling between the hydrodynamic equation and the phase-field equation in two-phase incompressible flows,it is desirable to develop efficient and high-order accurate numerical schemes that can decouple these two equations.One popular and efficient strategy is to add an explicit stabilizing term to the convective velocity in the phase-field equation to decouple them.The resulting schemes are only first-order accurate in time,and it seems extremely difficult to generalize the idea of stabilization to the second-order or higher version.In this paper,we employ the spectral deferred correction method to improve the temporal accuracy,based on the first-order decoupled and energy-stable scheme constructed by the stabilization idea.The novelty lies in how the decoupling and linear implicit properties are maintained to improve the efficiency.Within the framework of the spatially discretized local discontinuous Galerkin method,the resulting numerical schemes are fully decoupled,efficient,and high-order accurate in both time and space.Numerical experiments are performed to validate the high-order accuracy and efficiency of the methods for solving phase-field models of two-phase incompressible flows.

Accurate Symbolic Solution of Ginzburg-Landau Equations in the Circular Cell Approximation by Variational Method: Magnetization of Ideal Type II Superconductor

In this paper I access the degree of approximation of known symbolic approach to solving of Ginzburg-Landau (GL) equations using variational method and a concept of vortex lattice with circular unit cells, refine it in a clear and concise way, identify and eliminate the errors. Also, I will improve its accuracy by providing for the first time precise dependencies of the variational parameters;correct and calculate magnetisation, compare it with the one calculated numerically and conclude they agree within 98.5% or better for any value of the GL parameter k and at magnetic field , which is good basis for many engineering applications. As a result, a theoretical tool is developed using known symbolic solutions of GL equations with accuracy surpassing that of any other known symbolic solution and approaching that of numerical one.

AI深度学习对早期肺腺癌不同病理类型的精准识别

目的 探讨人工智能(AI)深度学习对早期肺腺癌的不同病理类型诊断效能,分析AI深度学习对不同病理类型应用价值。方法 选取经手术病理证实为早期肺腺癌患者90例的CT图像,按照病理类型分为原位腺癌组、微小浸润性腺癌组、浸润性腺癌组,每组30例,并按照2:1的比例随机分为训练组(n=60例)与验证组(n=30例),利用联影AI科研平台半自动分割靶病灶并提取影像组学特征,利用验证组的数据测试训练深度学习模型,分析病灶CT形态特征,计算病灶CT定量参数,并对肺腺癌的病理类型进行预测评分,分析诊断效能。结果 三组在性别、年龄、结节位置、结节大小、结节体积、结节质量、最小CT值、空泡征等比较,差异无统计学意义(P>0.05);在结节密度、长径、短径、体积、AI预测得分、最大CT值、平均CT值、分叶征、血管集束征、毛刺征、胸膜凹陷征结果比较,差异有统计学意义(P<0.05)。浸润性腺癌的长径、短径、直径高于原位腺癌组和微小浸润性腺癌组;浸润性腺癌组的AI预测得分、最大CT值、平均CT值高于原位腺癌组和微小浸润性腺癌组;浸润性腺癌组在分叶征、血管集束征、毛刺征、胸膜凹陷征的比例高于原位腺癌组和微小浸润性腺癌组。结论 基于AI学习在诊断肺腺癌不同病理类型中具有较高的诊断价值,能够精准识别不同的病理类型,具有较高的可重复性和操作性。

Global Calibration Method for Monocular Multi-View System Using Rotational Dual-Target

To make the problems of existing high requirements of calibration tools, complex global calibration process addressed for monocular multi-view visual measurement system during measurement, in the paper, a global calibration method is proposed for the geometric properties of rotational correlation motion and the absolute orientation of the field of view without over lap. Firstly, a dual-camera system is constructed for photographing and collecting the rotating image sequence of two flat targets rigidly connected by a long rod at different positions, and based on the known parameters, such as, target feature image, world coordinates, camera internal parameters and so on, then the global PnP optimization method is used to solve the rotation axis and the reference point at different positions;Then, the absolute orientation matrix is constructed based on the parameters of rotation axis, reference point and connecting rod length obtained by this method. In the end, the singular value decomposition method is used to find the optimal rotation matrix, and then get the translation matrix. It’s shown based on simulation and actual tests that in comparison with the existing methods, the maximum attitude and pose errors is 0.0083˚ and 0.3657 mm, respectively, which improves the accuracy by 27.8% and 24.4%, respectively. The calibration device in this paper is simple, and there are no parallel, vertical and coplanar requirements between multiple rotating positions. At the same time, in view of the calibration accuracy, the accuracy requirements of most application scenarios can be met.

基于AHP+异构信息网络的高校精准志愿服务模型研究

教育数字化是教育高质量发展的应有之义和必由之路。文章在教育数字化背景下,将数字化技术手段应用到高校志愿服务研究中,讨论了党委引领下的高校精准志愿服务构建目标及原则,搭建了基于层次分析法和异构信息网络的高校精准志愿服务算法模型,力图实现多态化服务、精准化服务对象匹配、多维度评估的高校精准志愿服务,为高校德育建设培育新领域、新模式提供参考。

基于A-FA法的应收账款融资客户资信评估

为了帮助应收账款融资业务中银行(或金融机构)对客户资信进行评估,从客户素质、资金实力、资金信用、盈利能力、合同及商务结算5个因素出发,筛选出业内经营能力等16项指标,建立了资信评估指标体系。考虑指标的特性,构建了基于A-FA法的资信评估模型,以层次分析法确立各层级评价指标的相对权重。对于模糊性指标,运用模糊综合评价法进行评价。对于有确定值的指标,采用精确值测评法给予评分。两个评分的总和则为资信评估的总得分,由此得到客户的资信等级。最后,由算例进行实证分析。研究结果表明:该模型在资信评估方面具有较好的可靠性和适用性,评价结果能为银行(或金融机构)对客户进行资信评估提供参考依据。

对话人工智能科学家Q&A(上)

青少年要培养良好的科学素养,提升逻辑思维能力、探究能力,离不开科学“引路人”。编辑部通过浙江省青年高层次人才协会邀请到三位人工智能相关领域的科学家,就“人工智能”这一话题与我们的读者展开一场对话。

基于CRISPR/Cas12a的生物传感平台的机制研究及应用

CRISPR/Cas12a系统能够由可编程的RNA引导,准确识别特异的单链DNA或含有PAM序列的双链DNA,而后在目标底物进行切割的同时完成对非特异性单链DNA的迅速切割,该特性使其在生物传感应用中显示出巨大前景。近年来,CRISPR/Cas12a系统被广泛应用于生物标志物的辅助检测,其生物标志物传感平台已在可视化细胞途径、体内活体诊断等生物分子传感器的构建方面得到应用。本文基于CRISPR/Cas12a生物传感平台的构建原理,对不同应用情景下CRISPR/Cas12a系统的变体进行了总结,并对基于该系统的体外、体内传感平台的应用进行了重点介绍和归纳,进一步讨论了不同传感平台的特点。最后对目前应用的优点和局限性做出总结和展望,以期为该领域的研究与应用提供一定参考。

An Efficient Accurate Direct Solution of Poisson's Equation for Computation of Meteorological Parameters

Poisson's equation is solved numerically by two direct methods, viz. Block Cyclic Reduction (BCR) method and Fourier Method. Qualitative and quantitative comparison between the numerical solutions obtained by two methods indicates that BCR method is superior to Fourier method in terms of speed and accuracy. Therefore. BCR method is applied to solve (?)2(?)= ζ and (?)2X= D from observed vorticity and divergent values. Thereafter the rotational and divergent components of the horizontal monsoon wind in the lower troposphere are reconstructed and are com pared with the results obtained by Successive Over-Relaxation (SOR) method as this indirect method is generally in more use for obtaining the streamfunction ((?)) and velocity potential (X) fields in NWP models. It is found that the results of BCR method are more reliable than SOR method.