Base force element method of complementary energy principle for large rotation problems

Using the concept of the base forces, a new finite element method （base force element method, BFEM） based on the complementary energy principle is presented for accurate modeling of structures with large displacements and large rotations. First, the complementary energy of an element is described by taking the base forces as state variables, and is then separated into deformation and rotation parts for the case of large deformation. Second, the control equations of the BFEM based on the complementary energy principle are derived using the Lagrange multiplier method. Nonlinear procedure of the BFEM is then developed. Finally, several examples are analyzed to illustrate the reliability and accuracy of the BFEM.

Extended state observer-based control with an adjustable parameter for a large ground-based telescope

The high-precision requirements will always be constrained due to the complicated operating conditions of the ground-based telescope. Owing to various internal and external disturbances, it is necessary to study a control method, which should have a good ability on disturbance rejection and a good adaptability on system parameter variation. The traditional proportional-integral(PI) controller has the advantage of simple and easy adjustment, but it cannot deal with the disturbances well in different situations. This paper proposes a simplified active disturbance rejection control law, whose debugging is as simple as the PI controller, and with better disturbance rejection ability and parameter adaptability. It adopts a simplified second-order extended state observer(ESO) with an adjustable parameter to accommodate the significant variation of the inertia during the different design stages of the telescope. The gain parameter of the ESO can be adjusted online with a recursive least square estimating method once the system parameter has changed significantly. Thus, the ESO can estimate the total disturbances timely and the controller will compensate them accordingly. With the adjustable parameter of the ESO, the controller can always achieve better performance in different applications of the telescope. The simulation and experimental verification of the control law was conducted on a 1.2-meter ground based telescope. The results verify the necessity of adjusting the parameter of the ESO, and demonstrate better disturbance rejection ability in a large range of speed variations during the design stages of the telescope.

Programmable Logic Based on Large Magnetoresistance of Germanium

We find extremely large low-magnetic-field magnetoresistance （~350% at 0.2 T and ~180% at 0.1 T） in germa- nium at room temperature and the magnetoresistanee is highly sensitive to the surface roughness. This unique magnetoelectric property is applied to fabricate logic architecture which could perform basic Boolean logic in- cluding AND, OR, NOR and NAND. Our logic device may pave the way for a high performance microprocessor and may make the germanium family more advanced.

Seismic response reduction analysis of large chassis base-isolated structure under long-period ground motions

Long-period structures(e.g.Isolated structures)tend to produce pseudo-resonance with low frequency compo-nents of long-period ground motions,resulting in the increase in damage.Stiffness mutation occurs due to the set-back in the upper body of the large chassis structure.In the parts with stiffness mutation,the torsion effect caused by the tower is far greater than that of the chassis itself.In this study,a total of 273 ground motions are collected and then filtered into four types,including the near-field ordinary,near-field pulse,far-field ordinary,and far-field harmonic.An 8-degree(0.2 g)fortified large chassis base-isolated structure is established.Furthermore,ETABS program software is used to conduct nonlinear time history analysis on the isolation and seismic model under bi-directional earthquake ground motions.The comparison results show that the seismic isolation effect of the base-isolated structure under long-period ground motions is worse than that associated with ordinary ground motions when the seismic response reduction rate of the large base floor significantly decreases compared with that of the tower.When the inter-story displacement angle and the displacement of isolation layer of the chassis exceeds the limit of Code for Seismic Design of Buildings(GB 50011-2010),it is recommended to adopt composite seismic isolation technology or add limit devices.Under the condition of long-period ground motions,the base-isolated structure reduces the lateral-torsional coupling effect of the large chassis structure,while the torsion response of large chassis’top layer increases.Under long-period ground motions with the same acceleration peak,the response of the base-isolated structure increases much more than that of the seismic structure and the consideration of this impact is suggested to be added to the Code.

Benchmark Dose Estimation for Cadmium-Induced Renal Effects Based on a Large Sample Population from Five Chinese Provinces

A survey involving 6103 participants from five Chinese provinces was conducted to evaluate the threshold value of urinary cadmium （UCd） for renal dysfunction as benchmark dose low （BMDL）. The urinary N-acetyl-13-D-glucosaminidase （UNAG） was chosen as an effect biomarker. The UCd BMDLs for UNAG ranged from 2.18μg/g creatinine （cr） to 4.26μg/g cr in the populations of different provinces. The selection of the sample population and area affect the evaluation of the BMDL. The reference level of UCd for renal effects was further evaluated based on the data of all 6103 subjects. With benchmark responses （BMR） of 10%/5%, the overall UCd BMDLs for males in the total population were 3.73/2.08 μg/g cr. The BMD was slightly lower in females, thereby indicating that females may be relatively more sensitive to Cd exposure than are males.

Minto Large Igneous Province: A 2.00 Ga Mafic Magmatic Event in the Eastern Superior Craton Based on U-Pb Baddeleyite Geochronology and Paleomagnetism

A precise U-Pb baddeleyite age of 1999±2 Ma has been obtained for the NNW trending Lac Shpogan dyke swarm of the James Bay area of the eastern Superior craton.Previously the age of the swarm was only

CMA:an efficient index algorithmof clustering supporting fast retrieval oflarge image databases

To realize content-hased retrieval of large image databases, it is required to develop an efficient index and retrieval scheme. This paper proposes an index algorithm of clustering called CMA, which supports fast retrieval of large image databases. CMA takes advantages of k-means and self-adaptive algorithms. It is simple and works without any user interactions. There are two main stages in this algorithm. In the first stage, it classifies images in a database into several clusters, and automatically gets the necessary parameters for the next stage-k-means iteration. The CMA algorithm is tested on a large database of more than ten thousand images and compare it with k-means algorithm. Experimental results show that this algorithm is effective in both precision and retrieval time.

Understanding the Dynamics Location of Very Large Populations Interacted with Service Points

This paper offers preliminary work on system dynamics and Data mining tools. It tries to understand the dynamics of carrying out large-scale events, such as Hajj. The study looks at a large, recurring problem as a variable to consider, such as how the flow of people changes over time as well as how location interacts with placement. The predicted data is analyzed using Vensim PLE 32 modeling software, GIS Arc Map 10.2.1, and AnyLogic 7.3.1 software regarding the potential placement of temporal service points, taking into consideration the three dynamic constraints and behavioral aspects: a large population, limitation in time, and space. This research proposes appropriate data analyses to ensure the optimal positioning of the service points with limited time and space for large-scale events. The conceptual framework would be the output of this study. Knowledge may be added to the insights based on the technique.

Force-Based Quadrilateral Plate Bending Element for Plate Using Large Increment Method

A force-based quadrilateral plate element( 4NQP13) for the analysis of the plate bending problems using large increment method( LIM) was proposed. The LIM, a force-based finite element method( FEM),has been successfully developed for the analysis of truss,beam,frame,and 2D continua problems. In these analyses,LIMcan provide more precise stress results and less computational time consumption compared with displacement-based FEM. The plate element was based on the Mindlin-Reissner plate theory which took into account the transverse shear effects.Numerical examples were presented to study its performance including accuracy and convergence behavior,and the results were compared with the results have been obtained from the displacementbased quadrilateral plate elements and the analytical solutions. The4NQP13 element can analyze the moderately thick plates and the thin plates using LIMand is free from spurious zero energy modes and free from shear locking for thin plate analysis.

APPLICATION OF HYBRID GENETIC ALGORITHM IN AEROELASTIC MULTIDISCIPLINARY DESIGN OPTIMIZATION OF LARGE AIRCRAFT

The genetic/gradient-based hybrid algorithm is introduced and used in the design studies of aeroelastic optimization of large aircraft wings to attain skin distribution,stiffness distribution and design sensitivity.The program of genetic algorithm is developed by the authors while the gradient-based algorithm borrows from the modified method for feasible direction in MSC/NASTRAN software.In the hybrid algorithm,the genetic algorithm is used to perform global search to avoid to fall into local optima,and then the excellent individuals of every generation optimized by the genetic algorithm are further fine-tuned by the modified method for feasible direction to attain the local optima and hence to get global optima.Moreover,the application effects of hybrid genetic algorithm in aeroelastic multidisciplinary design optimization of large aircraft wing are discussed,which satisfy multiple constraints of strength,displacement,aileron efficiency,and flutter speed.The application results show that the genetic/gradient-based hybrid algorithm is available for aeroelastic optimization of large aircraft wings in initial design phase as well as detailed design phase,and the optimization results are very consistent.Therefore,the design modifications can be decreased using the genetic/gradient-based hybrid algorithm.

An Intelligent Master Model of Computer Aided Process Planning for Large Complicated Stampings

Process planning for large complicated stampings is more complicated, illegible and multiform than that for common stampings. In this paper, an intelligent master model of computer aided process planning （CAPP） for large complicated stampings has been developed based on knowledge based engineering （KBE） and feature technology. This innovative model consists of knowledge base （KB）, process control structure （PCS）, process information model （PIM）, multidisciplinary design optimization （MDO）, model link environment （MLE） and simulation engine （SE）, to realize process planning, optimization, simulation and management integrated to complete intelligent CAPP system. In this model, KBE provides knowledge base, open architecture and knowledge reuse ability to deal with the multi-domain and multi-expression of process knowledge, and forms an integrated environment. With PIM, all the knowledge consisting of objects, constraints, cxtmricncc and decision-makings is carried by object-oriented method dynamically for knowledge-reasoning. PCS makes dynamical knowledge modified and updated timely and accordingly. MLE provides scv. cral methods to make CAPP sysmm associated and integrated. SE provides a programmable mechanism to interpret simulation course and result. Meanwhile, collaborative optimization, one method of MDO, is imported to deal with the optimization distributed for multiple purposes. All these make CAPP sysmm integrated and open to other systems, such as dic design and manufacturing system.

Analysis on the Effect of Shading on the Characteristics of Large-scale on-grid PV System in China

Because of rich solar resource and low land cost, a lot of large-scale ground-based grid-connected PV systems have been built in Northwest China. In this paper, some shading phenomena on a grid-connected PV system inNorthwest Chinaare classified and analyzed. Through the I-V curve test of PV modules, it can be seen that dust influence system performance of the grid-connected PV system. And the experimental results have shown that shading could affect the electrical properties of PV modules. Meanwhile, same shading area on different shading positions could have different impacts on the identical PV module.

柴达木盆地卤水钾盐迁聚规律与找矿新突破

钾盐是我国大宗紧缺战略性“粮食”矿产,对保障国家粮食安全具有重要意义。我国钾盐资源具有需求量大、对外依存度高等特点,寻找新的钾盐矿床、形成新的大型钾盐资源基地刻不容缓。2023年,中国地质调查局组织开展青海柴达木盆地钾盐“增储保供”地质调查工作,在前期对柴达木盆地成盐聚钾规律性认识的基础上,于柴西北大浪滩—黑北凹地部署实施了“探采一体化”柴钾1井,钻获1021.95 m(井深111.54~1133.49 m)巨厚松散砂砾储卤层,全井段抽卤试验获日稳定涌水量8586 m^(3)/d、水位降深11.3 m、单位涌水量759.89 m^(3)/d·m、氯化钾平均含量为0.54%的高产工业品位“砂砾型”卤水钾矿,取得了柴达木盆地陆相深层卤水钾盐找矿新突破,为形成中国新的亿吨级大型钾盐基地夯实了资源基础。

卫生领域人工智能的伦理与治理:多模态大模型指南

2024年,世界卫生组织发布了“Ethics and governance of artificial intelligence for health.Guidance on large multi-modal models”,将其翻译成中文《卫生领域人工智能的伦理与治理:多模态大模型指南》供中国的同仁参阅,协助规划与卫生领域多模态大模型有关的益处和挑战,并为适当开发、提供和使用多模态大模型提供政策和实践方面的指导。世界卫生组织咨询了20位人工智能领域的顶尖专家,他们确定了在卫生领域使用人工智能的潜在益处和潜在风险,并发布了以协商方式达成一致的六项原则,供正在使用人工智能的政府、开发者和提供者在制定政策和实践时考虑。指南提供了与指导原则相一致的企业内部、政府和国际合作的治理建议,指南的基础是考虑到人类使用卫生领域生成式人工智能独特方式的指导原则和治理建议。生成式人工智能是算法在可用于生成新内容的数据集上进行训练的一种人工智能技术。指南针对其中一种类型的生成式人工智能,即多模态大模型,这种模型可以接受一种或多种类型的数据输入,并产生不局限于输入算法的数据类型的多种输出。据预测,多模态大模型将广泛应用于医疗保健、科学研究、公共卫生和药物开发等领域。多模态大模型也被称为“通用基础模型”,尽管尚未证实多模态大模型能否完成各种任务和目的。

大型封闭空间中UWB定位基站拓扑的通用设计方法

超宽带(ultra-wide band,UWB)技术是无人装备在巡检具有多障碍物的大型封闭空间时获取定位坐标的主要方法之一。目前主要依赖人工方式设计UWB定位基站拓扑的构型、位置和数量。这种方式存在设计效率低下,设计效果未知,性价比难以确定等问题。为此,本文提出了一套较为科学完善的定位基站拓扑评价体系,并提出了一种在大型封闭空间中自动设计定位基站拓扑的通用方法。该方法以仿真模拟为基础,通过遗传算法结合拓扑评价体系,自动生成贴合实际应用场景的最优拓扑方案,包括最优的基站布设数量以及布设位置信息。实验结果表明:1)经通用设计方法生成的拓扑相比使用基站数量最多的拓扑,综合性能提高了6.2%;相比使用基站数量最少的拓扑,综合性能提高了21.2%。2)经通用设计方法生成的拓扑相比人工设计的锯齿形拓扑,综合性能提高了11.4%,设计效率提高了92.9%。可见,针对具有多障碍物的大型封闭空间场景,本文的方法可以在较短的时间内设计出综合性能较优,性价比较高的定位基站拓扑,为无人装备在此类大型封闭空间中开展全自主定位和巡检奠定了基础。

大模型智能体:概念、前沿和产业实践

从符号型和反应型智能体到基于强化学习和迁移学习的智能体,再到当前基于大模型的智能体,AI智能体经历了三代发展,逐渐成为人工智能研究和应用的核心。其中基于大模型的智能体是能够更准确地感知环境、进行反应和判断、形成并执行决策的智能计算实体,在多个领域展现出广泛的应用前景,包括图像生成、视频生成、数据分析、图文修改辅助、谈判指导、教育教学、学术研究、生活助手、网站开发等。OpenAI、Google、Apple、NVIDIA等国外厂商,以及腾讯、百度、商汤、联想、讯飞等国内厂家,都在大模型智能体领域进行了积极的探索与实践,推出了各自的大模型智能体产品,涵盖了游戏、生活、线上助手、营销、教育等多个领域。本文将回顾AI智能体的定义与发展,着重介绍大模型智能体的概念和发展前沿,以及大模型智能体在产业实践方面的代表性成果,为有志于大模型智能体研究和开发的读者提供参考。

基于项目的学习法联合慕课在医学统计学教学中的应用与思考

医学统计学课程教学团队从研究生医学统计学课程教学现状和存在问题出发,提出基于项目的学习法(project-based learning,PBL)联合大规模开放在线课程(massive open online courses,MOOC),即慕课的教学模式。本文对这种新型教学模式在研究生医学统计学课程的操作实施过程进行详细阐述,并对教学效果进行比较分析。结果表明PBL联合MOOC教学模式在提高学生的学习兴趣和动力、拓展学习资源和学习路径等方面具有优势,与传统教学模式相互补充和融合是解决当前研究生医学统计学课程学习瓶颈的有效途径,为当前医学院校研究生课程的教学改革与实践提供新思路。

模块化高压大容量DC/DC变换器综述

随着新能源发电占比增加和电网规模的不断扩大,直流输电系统的容量不断提升,含有不同电压等级的直流电网是未来发展的必然趋势。在此背景下,DC/DC变换器作为直流电网关键设备,在多电压等级互联场景中发挥着重要作用。文中首先对已有的模块化高压大容量DC/DC变换器进行归纳、分类和比较,然后阐述了目前模块化高压大容量DC/DC变换器的拓扑结构、工作原理与特点,并针对其特点提出了不同变换器的适用场景,最后对未来的研究方向提出了建议。

数字化转型背景下大规模考试机考体系的构建

数字化转型是教育考试顺应时代发展的必由之路,机考以其独特的优势成为大规模考试数字化转型的有效途径。专业考试机构应该结合人工智能、大数据等先进技术,深入探索大规模考试机考的实施策略,利用现代信息技术搭建大规模考试机考体系,改进命题工作方式,提高组考工作效率,优化考试智能评分系统,提升考试评价价值。同时,积极破解数字化转型中机考的数据安全、技术保障、试卷等值等难题,提升大规模考试综合管理的质效,以满足现代考试的需要。

大语言模型与知识图谱协同下高校AI项目导师构建研究——以“人工智能创新项目设计”为例

针对项目式学习面临的学习内容增加、知识体系重构以及学习方式变化等难题,提出了一种融合大语言模型(LLM)与知识图谱技术的高校AI项目导师系统构建方案。其中,大语言模型实现自然语言的理解和生成,而知识图谱负责专业知识库和增强大语言模型输出的可解释性和可靠性。高校AI项目导师能提供准确、个性化且全面的项目学习指导,使学习者有效应对各种复杂的项目式学习情境。“人工智能创新项目设计”课程的实证研究表明,采用高校AI项目导师系统显著提升了学生的课程参与度,促进了学生的工程创新素养、工程人文素养及AI素养三大核心素养的发展,并有效提高了学生对课程的满意度。这表明将大语言模型技术与知识图谱技术相结合而开发的在线教育工具,在提升教学质量、激发创新能力等方面展现出较高的发展潜力。