The Minimum Energy Principle in Description of Nonlinear Properties of Orthotropic Material

In this paper the conception of theoretical determine the relations between material experimental characteristics is presented. On the base of stress-strain relations for nonlinear elastic anisotropic material and geometrical interpretation of deformation state, the general form of strain energy density function was introduced. Using this function and variational methods the relations between material characteristics were achieved. All considerations are illustrated by a short theoretical example.

Mathematical Model and Simulation of Harmful Invasive Plant Control

Plant invasion refers to the phenomenon that some plants grow too fast due to they are far away from the original living environment or predators, affecting the local environment. With the development of tourism and trade, the harm caused by invasive plants will be more and more serious. Therefore, it is necessary to ex- plore an effective method for controlling plant invasion through qualitative and quan- titative research. In this paper, the models were established for the early and late harmful plant invasion control. The huge computation was completed by the com- puter programming to obtain the optimal solutions of the models. The real meaning of the optimal solution was further discussed. Through numerical simulations and discussion, it could be concluded that the quantitative research on the invasive plant control had a certain application value.

Minimum Normal Force Principle Based Quantitive Optimization of Clamping Forces for Thin Walled Part

Based on the stability criteria of workpiece-fixture system, quantitative optimization of clamping forces during precise machining process for thin walled part is studied considering the contact condition between wokpiece and locator, the contact mechanical model is achieved, which is further been used to calculate the entire passive forces acting on the statically undetermined workpiece by means of the force screw theory as well as minimum norm force principle. Furthermore, a new methodology to optimize clamping forces is put forward, on the criteria of keeping the stability of workpiece during cutting process. By this way, the intensity of clamping forces is decreased dramatically, which will be most beneficial for improving the machining quality of thin-walled parts. Finally, a case study is used to support and validate the proposed model.

A fast computational method for the landing footprints of space-to-ground vehicles

Fast computation of the landing footprint of a space-to-ground vehicle is a basic requirement for the deployment of parking orbits, as well as for enabling decision makers to develop real-time programs of transfer trajectories. In order to address the usually slow computational time for the determination of the landing footprint of a space-to-ground vehicle under finite thrust, this work proposes a method that uses polynomial equations to describe the boundaries of the landing footprint and uses back propagation(BP) neural networks to quickly determine the landing footprint of the space-to-ground vehicle. First, given orbital parameters and a manoeuvre moment, the solution model of the landing footprint of a space-to-ground vehicle under finite thrust is established. Second, given arbitrary orbital parameters and an arbitrary manoeuvre moment, a fast computational model for the landing footprint of a space-to-ground vehicle based on BP neural networks is provided.Finally, the simulation results demonstrate that under the premise of ensuring accuracy, the proposed method can quickly determine the landing footprint of a space-to-ground vehicle with arbitrary orbital parameters and arbitrary manoeuvre moments. The proposed fast computational method for determining a landing footprint lays a foundation for the parking-orbit configuration and supports the design of real-time transfer trajectories.

A nonlinear rheological model of backfill material for retaining roadways and the analysis of its stability

The long-term stability of backfill material is the key to retaining roadways successfully. In order to study the rheological deformation of backfill material and its long-term stability, given the visco-elastoplastic properties of this material, we introduced a softening and a hardening function for a new nonlinear the- ological model with time-varying parameters. Based on this, we presented the instability condition of this model by using the principle of minimum potential energy. Combined with engineering practice, we cal- culated the urlstable time period of backfill material. The results show that the time of instability of the backfill material relate to the initial parameters of the material, ＂the coefficients decided by temperature and the ratio of the plastic zone of the backfill material. Based on the results of our analysis from the point of view of energy, we can quickly obtain the time of instability of this model from our graphical analysis. The time of instability of the backfill material obtained from our investigation coincides with an actual project.

Tree Network Formation in Poisson Equation Models and the Implications for the Maximum Entropy Production Principle

This paper presents not only practical but also instructive mathematical models to simulate tree network formation using the Poisson equation and the Finite Difference Method (FDM). Then, the implications for entropic theories are discussed from the viewpoint of Maximum Entropy Production (MEP). According to the MEP principle, open systems existing in the state far from equilibrium are stabilized when entropy production is maximized, creating dissipative structures with low entropy such as the tree-shaped network. We prepare two simulation models: one is the Poisson equation model that simulates the state far from equilibrium, and the other is the Laplace equation model that simulates the isolated state or the state near thermodynamic equilibrium. The output of these equations is considered to be positively correlated to entropy production of the system. Setting the Poisson equation model so that entropy production is maximized, tree network formation is advanced. We suppose that this is due to the invocation of the MEP principle, that is, entropy of the system is lowered by emitting maximal entropy out of the system. On the other hand, tree network formation is not observed in the Laplace equation model. Our simulation results will offer the persuasive evidence that certifies the effect of the MEP principle.

A Geometrical Theorem about the Static Equilibrium of a Common-point-force System and its Application

A geometrical theorem for the static equilibrium of a common-point-force system has been proven by means of virtual-work principle: The equilibrium point of a common-point force system has a minimal weighted distance summation to every fixed point arbitrarily given on each force line with a weighing factor proportional to corresponding force value. Especially the mechanical simulating technique for its inverse problem has been realized by means of pulley block. The conclusions for the inverse problem derived from mechanic method are in accordance with that given by the pure mathematical method, and the self-consistence of the theorem and its inverse problem has been demonstrated. Some application examples in engineering, economy and mathematics have been discussed, especially the possible application in the research of molecular structure, has also been predicted.

Motion Equation and Solution of Mushroom Cloud

Using model like hot air bloom with zero-weighted membrane wrapped hot air, surrounded by cold air, this paper sets up a partial differential equation (PDE) of motion of mushroom cloud by modifying Navier-Stokes (N-S) equations. The obtained equation is a vector PDE. It states that the derivative of velocity is with respect to time proportions to the gradient of temperature with respect to trace. Its solution is obtained by the method of separating variables for scalar function. These results have been compared with well agreement with literatures. Highlight: The Principle of Minimum Energy Release (PMER) is used to prove the pulse-mode of explosion of nuclear weapon, as great Earthquake, and optimum path problems.

Giorgio Vasari and Mannerist Architecture： A Marriage of Beauty and Function in Urban Spaces

The first part of this essay deals with Giorgio Vasari＇s conception of architecture in sixteenth-century Italy, and the second part examines Vasari＇s practical application of one of his constructions, the loggia （open gallery or arcade） or corridoio （corridor）. The essay also discusses the merits of Vasari＇s open gallery （loggia） as a vernacular architectural construct with egalitarian functions and Vasari＇s principles of architecture （design, rule, order, and proportion） and beauty （delight and necessity） for the formulation of the theory of art in Mannerism, a sixteenth-century style of art.

Application of Optimal Control to the Epidemiology of Dengue Fever Transmission

In this paper, we build an epidemiological model to investigate the dynamics of the spread of dengue fever in human population. We apply optimal control theory via the Pontryagins Minimum Principle together with the Runge-Kutta solution technique to a “simple” SEIRS disease model. Controls representing education and drug therapy treatment are incorporated to reduce the latently infected and actively infected individual populations. The overall thrust is the minimization of the spread of the disease in a population by adopting an optimization technique as a guideline.

Flexible predictive power-split control for battery-supercapacitor systems of electric vehicles using IVHS

The utilization of traffic information received from intelligent vehicle highway systems(IVHS) to plan velocity and split output power for multi-source vehicles is currently a research hotspot. However, it is an open issue to plan vehicle velocity and distribute output power between different supply units simultaneously due to the strongly coupling characteristic of the velocity planning and the power distribution. To address this issue, a flexible predictive power-split control strategy based on IVHS is proposed for electric vehicles(EVs) equipped with battery-supercapacitor system(BSS). Unlike hierarchical strategies to plan vehicle velocity and distribute output power separately, a monolayer model predictive control(MPC) method is employed to optimize them online at the same time. Firstly, a flexible velocity planning strategy is designed based on the signal phase and time(SPAT) information received from IVHS and then the Pontryagin’s minimum principle(PMP) is adopted to formulate the optimal control problem of the BSS. Then, the flexible velocity planning strategy and the optimal control problem of BSS are embedded into an MPC framework, which is online solved using the shooting method in a fashion of receding horizon. Simulation results verify that the proposed strategy achieves a superior performance compared with the hierarchical strategy in terms of transportation efficiency, battery capacity loss, energy consumption and computation time.

Optimization of volume to point conduction problem based on a novel thermal conductivity discretization algorithm

A conduction heat transfer process is enhanced by filling prescribed quantity and optimized-shaped high thermal conductivity materials to the substrate. Numerical simulations and analyses are performed on a volume to point conduction problem based on the principle of minimum entropy generation. In the optimization, the arrangement of high thermal conductivity materials is variable, the quantity of high thermal-conductivity material is constrained, and the objective is to obtain the maximum heat conduction rate as the entropy is the minimum.A novel algorithm of thermal conductivity discretization is proposed based on large quantity of calculations.Compared with other algorithms in literature, the average temperature in the substrate by the new algorithm is lower, while the highest temperature in the substrate is in a reasonable range. Thus the new algorithm is feasible. The optimization of volume to point heat conduction is carried out in a rectangular model with radiation boundary condition and constant surface temperature boundary condition. The results demonstrate that the algorithm of thermal conductivity discretization is applicable for volume to point heat conduction problems.

预应力UHPC-NC组合梁结合面徐变剪应力分析

在恒载应力作用下,预应力UHPC-NC组合梁因两种材料不同的徐变特性及加载龄期的差异导致结合面产生徐变剪应力,分别采用解析法和有限元法对结合面徐变剪应力进行分析。在解析法中,用三角级数表示UHPC-NC结合面的应力分布,基于结合面上的变形协调,利用最小余能原理推导出结合面徐变剪应力计算公式。在有限元法中,将组合梁UHPC层与NC层均划分成四边形平面应力单元,对结合面则采用等效杆单元模拟。以T形截面预应力UHPC-NC组合梁为例进行计算方法的验证,两种方法的计算结果吻合良好,且研究发现徐变剪应力最大值位于梁端;在此基础上对影响结合面徐变剪应力分布的UHPC层压应力、梁高、计算龄期、环境年平均相对湿度等参数进行分析,结果表明:结合面徐变剪应力最大值随着UHPC层压应力、计算龄期、环境年平均相对湿度的增大而增大,但基本不随梁高变化;结合面徐变剪应力最大值的位置随着梁高的增大而逐步向跨中靠近,其他因素不影响应力最大值的位置。研究结果可为UHPC-NC组合梁结合面的抗剪设计提供参考。

基于综合赋权与云熵优化的园区综合能源系统评价

综合能源系统(integrated energy system,IES)作为能源转型中的重要环节已得到越来越多国家的广泛关注。构建一套匹配中国国情的综合能源系统评价体系和评价方法不仅能够为综合能源系统规划后评价打下基础,以此对规划方案进行优劣排序;还能够提高综合能源系统项目的管理水平,在制定统一、完整的综合能源系统综合评价标准时提供参考。为此,首先结合园区IES基本特征以及运行特性,构建包含经济性、可靠性、环保性以及智能友好性4个方面的综合评价指标体系;然后为解决IES在运行中的不确定性问题,对基于传统云物元模型的综合评价体系提出云熵优化,即考虑不同评价者对模糊性的可接受程度;为解决单一赋权方法可能导致的评价结果过于主观或过于客观的问题,选择基于最小鉴别信息原理将决策实验室法与熵权法相结合的综合赋权法,并采用变权法进一步完善综合评价指标;最后通过算例分析,验证所提综合评价体系的科学正确性。

论未成年人个人信息处理中最小必要原则的适用

《未成年人网络保护条例》《未成年人保护法》《个人信息保护法》等规定,处理未成年人个人信息时应当遵循最有利于未成年人原则以及最小必要原则,这两项原则在处理未成年人个人信息的场景下共同发挥着重要作用,但这两项原则的实践适用却存在相互冲突。对此,应当在未成年人个人信息处理场景下将最小必要原则作为最有利于未成年人原则的具体表现形式对待,从而将最小必要原则与最有利于未成年人原则二者的关系界定为手段与目的的关系,并在此种关系中明确,处理行为符合最小必要原则的要求时,即可认定为符合最有利于未成年人原则。在最小必要原则的适用问题上,应通过三阶比例原则构建相应的认定标准。其中,相关性阶层主要考量处理行为与实现未成年人最大利益之间的关系,必要性阶层以未成年人或监护人同意的内容为核心考量,均衡性阶层则发挥兜底性的作用,排除过度损害未成年人最大利益的处理行为。当处理行为通过这三阶层的考量时,即可认定符合最小必要原则与最有利于未成年人原则。

基于磁各向异性的管壁应力集中区域检测方法

针对应力集中导致管壁发生屈服失效的问题,提出了利用磁各向异性检测管壁应力集中区域的方法。从能量角度出发,研究了应力导致管壁产生磁各向异性的机理,建立了管壁当量应力与磁各向异性探头输出电压信号的数学模型,通过计算管壁的当量应力判断其是否发生屈服失效,搭建了应力检测实验平台。实验结果表明,应力会导致管壁产生磁各向异性,磁各向异性检测方法能够检测出管壁当量应力的变化趋势和主应力方向所在延长线的角度,进而判断管壁是否产生应力集中区域。

考虑耐久性的PEM燃料电池有轨电车自适应优化控制策略

针对燃料电池/锂电池/超级电容混合储能有轨电车在动态负载、启停循环、怠速循环、大功率运行时质子交换膜(PEM)燃料电池寿命衰减情况,提出Pontryagin极小值原理(PMP)与耐久性结合的能量管理策略。通过启停控制策略控制燃料电池的启动与停止,有效降低燃料电池启动次数;利用储能系统总体氢气消耗为经济性代价,燃料电池性能衰退指数为耐久性代价,构建联合代价函数;在满足期望条件下,实现协态变量随荷电状态实时变化的在线适应;将所提策略与传统极小值策略和状态机策略进行仿真对比。结果表明:城市循环工况中所提策略较于传统Pontryagin策略燃料电池峰值电流降低了33.2%,氢气消耗下降了12.50%;郊区循环工况中所提策略较传统Pontryagin策略峰值电流降低了21.88%,氢气消耗下降了40.39%。所提管理策略在不同工况下均有良好的适应能力,解决了传统PMP只能离线应用的缺点,将启停次数控制在较低水平,具有延寿燃料电池的能力。

论个人信息处理中合同所必需规则的扩张适用

合同所必需规则与告知同意规则构成企业合法处理个人信息的“两大支柱”。由于合同所必需规则无需取得个人“同意”,其理应成为企业的首选。然而,作为平台企业的一种日常经营行为,个性化营销却被欧盟排除在合同所必需规则的适用范围之外,且该立场为我国学界所普遍认同。从实际看来,限缩解释立场是规则借鉴背景下一种错误的“路径依赖”:其一,合同所必需规则具备独立的适用地位,适度的扩张并不会导致告知同意规则的“消融”;其二,限缩解释路径既不足以从信息自决理论中推导而出,亦与我国个人信息保护的制度目标相违背。借助比较研究及案例分析,可以类型化方式对合同所必需规则的扩张适用路径予以具体阐明。作为争议的核心,个性化营销场景之于合同所必需规则的适用可通过合同目的和比例原则的考量予以单独证成。

静置工况条件下掺氢天然气浓度分布规律

利用天然气管道进行掺氢输送已成为氢能及天然气输送领域的热点和重点,但当前业界对于掺氢天然气在管道输送和停输静置过程中是否会自发分层一直存在较大争议。为了厘清该问题,以掺氢天然气在管道中静置这一极端工况为例,基于热力学能量最小原理,推导了在重力场作用下掺氢天然气浓度分布数学模型,并采用Peng-Robinson真实气体状态方程对该数学模型进行了求解,最后研究了甲烷—氢气二元组分混合气体在4种典型场景高度和5种掺氢比下氢浓度随高度的分布规律。研究结果表明:(1)在重力影响下管道顶部和底部的氢浓度存在差异,但其受高度差的影响显著,对于米级的水平管道、几十米级的一般城镇楼宇天然气立管、百米级的高层楼宇天然气立管,氢浓度随高度变化的差异微小,可完全忽略氢分层;(2)对于千米级大落差的掺氢天然气管道,当掺氢比不超过20%时,氢分层仍可忽略,但当掺氢比很高时(例如50%)管道顶部和底部的氢浓度差将超过1%,此时需考虑工程实际情况评估能否忽略氢分层;(3)西气东输某管道考虑真实气体组成、掺氢比20%、管道落差200 m时,各气体组分的浓度随落差高度的分布规律揭示了在实际工程中此类落差高度的掺氢天然气氢分层可忽略。结论认为,对于掺混均匀的掺氢天然气在静置这种最容易发生分层的极端工况下,如果不存在千米级极端大落差和极端大掺氢比,掺氢天然气管道分层现象可完全忽略;该认识从理论上厘清了目前关于掺氢天然气分层现象的争议,对掺氢天然气管道安全输送具有重要指导意义。

缆式焊丝GMAW焊缝截面侧偏行为机理分析

缆式焊丝熔化极气体保护电弧焊(gas metal arc welding,GMAW)中存在的焊缝截面侧偏现象会导致焊接接头熔合不良,基于熔滴受力分析和最小电压理论对焊缝截面侧偏现象的变化规律进行机理分析.结果表明,电流是影响截面侧偏的关键因素,由于缆式焊丝独特的绞合结构引起电弧旋转,进而导致出现熔滴受力不均的现象,熔滴过渡方向与焊丝轴线存在夹角,在熔滴冲击力的作用下导致焊缝截面出现侧偏现象,随着电流的增加,电弧对熔滴的拘束增强,熔滴过渡方向逐渐趋于轴线,因而焊缝截面侧偏的趋势随着电流增加而减小.