GLIMMER Antarctic Ice Sheet Model,an experimental research of moving boundary condition

A 3-D coupled ice sheet model, GLIMMER model is introduced, and an idealized ice sheet experiment under the EISMINT-1 criterion of moving boundary condition is presented. The results of the experiment reveal that for a steady-state ice sheet profile the characteristic curves describe the process of evolution which are accordant with theoretical estimates. By solving the coupled thermodynamics equations of ice sheet, one may find the characteristic curves which derived from the conservation of the mass, energy and momentum to the ice flow profile. At the same time, an agreement, approximate to the GLIMMER case and the confirmed theoretical results, is found. Present study is explorihg work to introduce and discuss the handicaps of EISMINT criterion and GLIMMER, and prospect a few directions of the GLIMMER model.

Greenland Ice Sheet Contribution to Future Global Sea Level Rise based on CMIP5 Models

Sea level rise （SLR） is one of the major socioeconomic risks associated with global warming. Mass losses from the Greenland ice sheet （GrIS） will be partially responsible for future SLR, although there are large uncertainties in modeled climate and ice sheet behavior. We used the ice sheet model SICOPOLIS （Simulation COde for POLythermal Ice Sheets） driven by climate projections from 20 models in the fifth phase of the Coupled Model Intercomparison Project （CMIP5） to estimate the GrlS contribution to global SLR. Based on the outputs of the 20 models, it is estimated that the GrIS will contribute 0-16 （0-27） cm to global SLR by 2100 under the Representative Concentration Pathways （RCP） 4.5 （RCP 8.5） scenarios. The projected SLR increases further to 7-22 （7-33） cm with 2~basal sliding included. In response to the results of the multimodel ensemble mean, the ice sheet model projects a global SLR of 3 cm and 7 cm （10 cm and 13 cm with 2~basal sliding） under the RCP 4.5 and RCP 8.5 scenarios, respectively. In addition, our results suggest that the uncertainty in future sea level projection caused by the large spread in climate projections could be reduced with model-evaluation and the selective use of model outputs.

Coupled Models and Parallel Simulations for Three-Dimensional Full-Stokes Ice Sheet Modeling

A three-dimensional full-Stokes computational model is considered for determining the dynamics,temperature,and thickness of ice sheets.The governing thermomechanical equations consist of the three-dimensional full-Stokes system with nonlinear rheology for the momentum,an advective-diffusion energy equation for temperature evolution,and a mass conservation equation for ice-thickness changes.Here,we discuss the variable resolution meshes,the finite element discretizations,and the parallel algorithms employed by the model components.The solvers are integrated through a well-designed coupler for the exchange of parametric data between components.The discretization utilizes high-quality,variable-resolution centroidal Voronoi Delaunay triangulation meshing and existing parallel solvers.We demonstrate the gridding technology,discretization schemes,and the efficiency and scalability of the parallel solvers through computational experiments using both simplified geometries arising from benchmark test problems and a realistic Greenland ice sheet geometry.

Advanced Sheet Pile Curtain Design: Case Study of Cotonou East Corniche

This paper delves into the critical aspects of sheet pile walls in civil engineering, highlighting their versatility in soil protection, retention, and waterproofing, all while emphasizing sustainability and efficient construction practices. The paper explores two fundamental approaches to sheet pile design: limit equilibrium methods and numerical techniques, with a particular focus on finite element analysis. Utilizing the robust PLAXIS 2016 calculation code based on the finite element method and employing a simplified elastoplastic model (Mohr-Coulomb), this study meticulously models the interaction between sheet pile walls and surrounding soil. The research offers valuable insights into settlement and deformation patterns that adjacent buildings may experience during various construction phases. The central objective of this paper is to present the study’s findings and recommend potential mitigation measures for settlement effects on nearby structures. By unraveling the intricate interplay between sheet pile wall construction and neighboring buildings, the paper equips engineers and practitioners to make informed decisions that ensure the safety and integrity of the built environment. In the context of the Cotonou East Corniche development, the study addresses the limitations of existing software, such as RIDO, in predicting settlements and deformations affecting nearby buildings due to the substantial load supported by sheet pile walls. This information gap necessitates a comprehensive study to assess potential impacts on adjacent structures and propose suitable mitigation measures. The research underscores the intricate dynamics between sheet pile wall construction and its influence on the local environment. It emphasizes the critical importance of proactive engineering and vigilant monitoring in managing and mitigating potential hazards to nearby buildings. To mitigate these risks, the paper recommends measures such as deep foundations, ground improvement techniques, and retrofitting. The findings presented in this study contribute significantly to the field of civil engineering and offer invaluable insights into the multifaceted dynamics of construction-induced settlement. The study underscores the importance of continuous evaluation and coordination between construction teams and building owners to effectively manage the impacts of sheet pile wall construction on adjacent structures.

Theoretical studies on the binding energy of β-sheet models

In this paper,B3LYP and MP2 methods are used to investigate the binding energy of seventeen antiparallel and parallel β-sheet models. The results indicate that the binding energy obtained from B3LYP calculations is weaker than that obtained from MP2 calculations but the relative binding energy yielded by B3LYP is almost the same as that by MP2. For the antiparallel β-sheets in which two N―H···O═C hydrogen bonds can form either a large hydrogen-bonded ring or a small hydrogen-bonded ring,the binding energy increases obviously when one large ring unit is added,whereas it only changes slightly when one small ring unit is added because of the secondary electrostatic repulsive interaction existing in the small ring unit which is estimated to be about 20 kJ/mol. For the parallel β-sheet models,the binding energy increases almost exactly linearly with the increase of the chain length.

Application and comparison of different elastoplastic constitutive models for springback simulation of aluminum sheet forming

Springback is considered to be one of the most important problems in aluminum sheet stamp forming, leading to deviation from the designed target shape and assembly defects. In this study, a springback simulation model based on the benchmark of a Jaguar Land Rover aluminum panel is established. We embed several elastoplastic constitutive models （ Barlat＇ s 89, Barlat＇ s YLD2000, Yoshida-Uemori （YU） ＋ Barlat＇ s 89, and YU ＋ Barlat＇ s YLD2000） in the finite element model,in order to discuss the influence of the constitutive model selection on springback prediction in aluminum sheet forming.

NUMERICAL MODELLING OF GOLD-ROLLBONDING OF CLAD METAL SHEETS

An analytical model based on the rigid-plastic finite-element formulation for slightly compressible materials is newly proposed to examine the bonding behavior at the roll gap during clad metal sheets rolling. The interfacial elements inserted between the two metals, which are characteristic of the shear-susceptible deformation with the help of the shear factor in the expression of effective strain rate,are used to model the relative slidding at the interface. It is found that the proposed method is applicable to the simulation of clad metal sheets rolling.

Investigation of the diocotron instability of an infinitely wide sheet electron beam by using the macroscopic cold-fluid model theory

This paper investigates the diocotron instability of an infinitely wide relativistic sheet electron beam in conducting wMls propagating through a uniform magnetic field by using the macroscopic cold-fluid model theory. Assuming low- frequency perturbations with long axial wavelengths, the eigenvalue equation and the dispersion relation are acquired for a sheet electron beam with sharp boundary profile and uniform density. The results presented in this paper has developed the use of the macroscopic cold-fluid model theory by extending the parameter of the electron cyclotron frequency ωc to a wider usage range, which is restricted to be much larger than the plasma frequency ωp in the previous research work. Theoretical analyses and numerical calculations indicate that the transport of the sheet electron beam will be completely stabilized by augmenting the normalized beam thickness to a conductor gap larger than a threshold λb, which is greatly dependent on the parameter ωc/ωp. The larger ωc/ωp is, the smaller λb will be needed. Moreover, the system parameters, including the wave number kx of the perturbations and the relativistic mass factor γb, will also influence the growth rate of diocotron instability obviously.

Investigation of intense sheet electron beam transport using the macroscopic cold-fluid model and the single-particle orbit theory

The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.The results indicate that the envelopes and the tilted angles of the sheet electron beam obtained by the two theories are consistent.The single-particle orbit theory is more accurate due to its treatment of the space-charge fields in a rectangular drift tube.The macroscopic cold-fluid model describes the collective transport process in order to provide detailed information about the beam dynamics,such as beam shape,density,and velocity profile.The tilt of the elliptic sheet beam in a uniform magnetic field is carefully studied and demonstrated.The results presented in this paper provide two complete theories for systemically discussing the transport of the sheet beam and are useful for understanding and guiding the practical engineering design of electron optics systems in high power vacuum electronic devices.

Stress Relaxation of a Paper Sheet under Cyclic Load: An Experimental and Theoretical Model

Mechanical experiments have been performed to study the dynamic stress relaxation of a paper sheet material mainly used in food packaging industry. The material was cyclically tensile-loaded with a strain range between 2.4% and 4%. The time period for each cycle was 400 seconds. It was found that stress will decrease when the number of cycles increases in the case of upper load and vice versa in the case of lower load. At the same time, the stress to strain curves followed the same pattern as the one from the previous cycle. The stress relaxation behavior of each cycle has been analyzed and the dynamic relaxation modulus was derived. An improved model is proposed to describe the dynamic relaxation behavior of the paper sheet. This model shows a very good fit to the experimental results and trends of prediction are observed. Furthermore, the physical description of this model and the variation by the cycles is discussed.

安徽省居住建筑终端能耗及碳排放达峰研究

以安徽省既有居住建筑运行阶段为研究对象,采用能源平衡表法、LEAP模型、碳排放因子法和STIRPAT模型等工具和方法,预测碳排放峰值及影响因素,并提出技术路径和政策建议。研究结果表明:安徽省居住建筑实现碳达峰的最佳实施路径应采取蓝图情景。该情景下居住建筑运行阶段碳排放2025年达到峰值3429.29万t, 2060年回落至918.69万t。在影响因素方面,常住人口是居住建筑碳排放的主导因素,大小为-2.646;能源结构也对居住建筑碳排放产生了不小的影响,大小为-1.465,这得益于安徽省建筑消费能源结构的持续优化。因此,开展建筑电气化、发展可再生能源、限制一次能源的使用、优化能源结构至关重要。

Transmission Line Modelling of Geomagnetic Induction in the Ocean/Earth Conductivity Structure

During geomagnetic disturbances, electric fields induced in the Earth and in power systems, pipelines and submarine cables can interfere with the operation of these systems. Calculations for submarine cables are complicated by the need to consider not just the induction directly into the cable but also the earth potentials produced at the coast at each end of the cable. To determine the coast potentials, we present a new model of the ocean and earth conductivity structure that spans the whole length of a cable from one coast to another. Calculations are based on the generalised thin sheet approach introduced by Ranganayaki and Madden but converted to a transmission line model that can be solved using standard circuit theory techniques. It is shown how the transmission line model can be used to calculate the earth potential profile from one side of an ocean or sea to the other. Example calculations are presented for a shallow sea, a shallow ocean, and a deep ocean that are simplified approximations to the North Sea, Tasman Sea and Pacific Ocean and show that the peak potentials occur at the coast. An examination is also made of how the width of a shallow sea and the width of the continental shelf affect these coast potentials. The modelling technique and example results provide a guide for more detailed modelling of geomagnetic induction along the routes of specific submarine cables.

装配式陶瓷薄板单元组件系统施工技术

针对广东省珠海市横琴口岸通关大厅空间跨度大、层高高、墙面开口数量多、工期紧的难题,对项目整体视觉效果及总工期进行分析,决定采用装配式施工方法,根据支撑点的距离,设计为钢质竖向主龙骨、铝合金装配式挂件系统,面材采用陶瓷薄板。通过装配式施工技术,并运用BIM深化设计及测算单块陶瓷薄板的大小尺寸,并与龙骨通过转接件勾搭式连接,墙面采用单元装配式安装系统。最终证明装配式施工方法既可减少施工作业面,又可提高工作效率,降低安全隐患且与其他专业交叉施工互不影响,具有较大的推广价值。

面向AIGC的教育提示工程学习提示单设计及应用

在AIGC时代,如何合理运用大模型赋能课堂教学是目前应解决的关键问题。通过教育提示工程的理论指导设计学习提示单能够促进教育与大模型等新技术的有效融合。学习提示单是帮助中小学师生在课堂中合理适恰地运用大模型解决问题的一种学习资源,旨在通过运用教育提示工程的理论针对教育领域的提示词进行设计,从而解决大模型在课堂中的合理有效运用问题。针对中小学师生使用大模型遇到的诸如如何引导学生正确使用大模型、如何把控大模型的内容质量、如何规避大模型使用的伦理风险以及如何提高学生的批判性思维等问题,设计了基于三轮对话的T|BO-LRQET-P&R(简称LRQET)模型、学习提示单以及大模型的课堂教学应用模式。通过教育提示工程的理论设计学习提示单以助力师生的教与学。

基于Rubber-sheet模型的虹膜识别算法研究

为了实现对虹膜内外边界的精确定位,提出了改进的虹膜图像定位算法.虹膜图像预处理过程主要包括虹膜边界定位、归一化处理和图像增强三部分,其中虹膜图像边界定位是实现虹膜识别的重要前提.首先使用质心探测法确定其二值化虹膜图像的内边界中心,然后再对内边界进行曲线拟合,从而实现对虹膜内边界的定位.使用Canny算子进行边缘检测,确定虹膜图像外边界,完成对虹膜边界的定位.使用Rubber-sheet模型对经过定位的虹膜区域图像进行归一化处理,方便虹膜图像的信息提取和编码匹配.实验证明改进的算法有效提高了虹膜图像预处理效率.

多目标差分进化算法改进与电工钢片磁致伸缩模型参数辨识

准确且高效地辨识电工钢片磁致伸缩模型参数是模型在变压器铁心振动分析中的应用前提。针对现有单目标优化算法不能兼顾参数辨识精度和速度的问题,该文基于改进Jiles-Atherton-Sablik和Energetic模型相结合的磁致伸缩模型,将该模型的参数辨识转换为多目标优化问题。以磁滞回线和磁致伸缩曲线的均方根误差作为待优化的2个目标,建立参数辨识的多目标优化数学模型。基于该模型,从控制参数自适应技术、变异算子改进策略以及选择算子改进策略3个方面对多目标差分进化算法进行改进,从而提出一种采用改进多目标差分进化算法的磁致伸缩模型参数辨识方法。通过与现有方法对比,该文方法的磁滞回线求解精度提升17.84%,磁致伸缩曲线求解精度提升13.60%,辨识速度提升41.57%。

航道开挖对护岸结构影响的离心模型试验研究

为了研究航道开挖对新老护岸结构的影响,依托东宗线航道四改三工程,利用大型土工离心模型试验平台研究航道开挖对老挡墙护岸结构、新施工钢板桩的受力和变形特征的影响,得出航道开挖过程中板桩两侧土压力的分布规律。结果表明,随开挖深度增加,靠岸侧(主动侧)土压力逐渐减小;受板桩位移、变形及离心模型试验重液影响,临水侧(被动侧)土压力部分减小,底部土压力增大。开挖卸载导致老挡墙呈现向水侧移动且向后翻转的趋势。设计工况的极限开挖深度约为3.6 m,此时钢板桩顶部帽梁的水平位移达到0.069 m;对于6、8和10 m 3种长度的板桩,其极限开挖深度约为0.5~0.6倍桩长,且随着桩长增加极限开挖深度逐渐降低。研究得出不同板桩长度下开挖深度的阈值,可为工程建设提供技术参数。

基于Energetic和改进Jiles-Atherton-Sablik模型的电工钢片动态磁致伸缩特性模拟

准确模拟电工钢片的动态磁致伸缩特性是电工装备铁心振动和噪声分析的关键步骤。该文提出一种基于Energetic磁滞模型和改进Jiles-Atherton-Sablik(J-A-S)模型的电工钢片动态磁致伸缩特性模拟方法。首先,基于静态Energetic磁滞模型和损耗分离理论,考虑由励磁频率引起的动态损耗密度分量,并采用场分离技术建立动态Energetic磁滞模型。其次,将动态Energetic磁滞模型求解的动态磁场强度作为改进J-A-S模型的已知量,从而根据铁磁材料的非线性本构关系,建立以磁感应强度为输入量的动态磁致伸缩逆模型。在此基础上,设计电工钢片动态磁致伸缩曲线的模拟流程。最后,将所提方法的模拟结果与实测结果和现有方法模拟结果进行对比,可知所提方法的模拟结果与实测结果吻合更好,从而验证所提模拟方法的准确性。

考虑回弹的水平上调式三辊卷板机卷圆精度研究

为提高卷圆成形精度,建立了不考虑回弹与考虑回弹时水平位移量与卷圆半径之间的理论模型。采用ABAQUS软件建立了卷圆成形有限元模型,并通过实验验证了理论模型及有限元模型的可靠性。基于可靠的有限元模型,研究了材料、摩擦力和板厚对卷圆成形精度的影响规律。研究结果表明,不考虑回弹时实验和仿真的成形半径与目标半径之间的误差分别为31.3%和20.7%。考虑回弹后的误差分别降低至2.2%和1.2%;在相同水平位移量下,材料的屈服强度越高,成形半径越大;摩擦力对成形半径的影响较小;板料越厚,成形半径越小。针对不同材料与不同厚度的板料卷圆成形,考虑回弹时的理论模型能够获得更精确的水平位移量,从而提升卷圆精度。