Theory of Flexural Shear, Bending and Torsion for a Thin-Walled Beam of Open Section

Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under transverse shear and axial torsional loading are each considered theoretically. These analyses involve the location of the shear centre at which transverse shear forces when applied do not produce torsion. This centre, when taken to be coincident with the centre of twist implies an equivalent reciprocal behaviour. That is, an axial torsion applied concentric with the shear centre will twist but not bend the beam. The respective bending and shear stress conversions are derived for each action applied to three aluminium alloy extruded channel sections mounted as cantilevers with a horizontal principal axis of symmetry. Bending and shear are considered more generally for other thin-walled sections when the transverse loading axes at the shear centre are not parallel to the section = s centroidal axes of principal second moments of area. The fixing at one end of the cantilever modifies the St Venant free angular twist and the free warping displacement. It is shown from the Wagner-Kappus torsion theory how the end constrained warping generates an axial stress distribution that varies with the length and across the cross-section for an axial torsion applied to the shear centre. It should be mentioned here for wider applications and validation of the Vlasov theory that attendant papers are to consider in detail bending and torsional loadings applied to other axes through each of the centroid and the web centre. Therein, both bending and twisting arise from transverse shear and axial torsion applied to each position being displaced from the shear centre. Here, the influence of the axis position upon the net axial and shear stress distributions is to be established. That is, the net axial stress from axial torsional loading is identified with the sum of axial stress due to bending and axial stress arising from constrained warping displacements at the fixing. The net shear stress distribution overlays the distributions from axial torsion and that from flexural shear under transverse loading. Both arise when transverse forces are displaced from the shear centre.

Rheological Behavior for Polymer Melts and Concentrated Solutions——Part Ⅶ: A Quantitative Verification for the Molecular Theory of Non-linear Viscoelasticity with Entanglement Constraints in Polymer Melts

Based on the molecular theory of non-linear viscoelasticity with constrained entanglements in polymer melts, the material functions in simple shear flow were formulated, the theoretical relations between. eta((gamma) over dot), psi (10)((gamma) over dot) and shear rate ((gamma) over dot), and topologically constrained dimension number n ' and a were derived. Linear viscoelastic parameters (eta (0) and G(N)(0)) and topologically constrained dimension number (n ' a and <(<upsilon>)over bar>) as a function of the primary molecular weight (M-n), molecular weight between entanglements (M-C) and the entanglement sites sequence distribution in polymer chain were determined. A new method for determination of viscoelastic parameters (eta (0), psi (10), G(N)(0) and J(e)(0)), topologically constrained dimension number (n ', a and v) and molecular weight (M-n, M-c and M-e) from the shear flow measurements was proposed. It was used to determine those parameters and structures of HDPE, making a good agreement between these values and those obtained by other methods. The agreement affords a quantitative verification for the molecular theory of nonlinear viscoelasticity with constrained entanglement in polymer melts.

Integrating Activity-Based Costing （ABC） and Theory of Constraint （TOC） for Improved and Sustained Cost Management

Implementing effective cost management approaches has recently gained momentum due to intense competition and increasing customer demands. Moreover, effective cost management approaches have contributed to firms＇ competitive advantage in relation to cost leadership strategy. Consequently, firms have implemented contemporary cost management systems, such as activity-based management, business process re-engineering, life-cycle costing, target costing, and theory of constraint （TOC）, to enable them to become low-cost producers and compete effectively and sustain their performance. Furthermore, focusing on cost management to improve profitability has led to the integration of activity-based costing （ABC） and TOC. Therefore, the aim of this study is to review literature and discuss how integration of ABC and TOC can result in improved and sustained cost management. While these methods have different approaches in addressing cost management, treating them as complementary cost management approaches can result in improved cost management due to improved product costing, improved cost reporting, improved product-mix decisions, and improved cycle-time management. Improvement in cost management will then result in sustained cost management. Sustained cost management is further enhanced with the investment in information customer and shareholder value technology that supports cross-functional decision making to continue creating to remain competitive in the market.

Modeling and Adaptive Neural Network Control for a Soft Robotic Arm With Prescribed Motion Constraints

This paper presents a dynamic model and performance constraint control of a line-driven soft robotic arm.The dynamics model of the soft robotic arm is established by combining the screw theory and the Cosserat theory.The unmodeled dynamics of the system are considered,and an adaptive neural network controller is designed using the backstepping method and radial basis function neural network.The stability of the closed-loop system and the boundedness of the tracking error are verified using Lyapunov theory.The simulation results show that our approach is a good solution to the motion constraint problem of the line-driven soft robotic arm.

Corporate Social Responsibility and Green Innovation-The Mediating Effect of Financing Constraints

Green innovation has become a strategic direction for the country and enterprises,and it is an important facet in achieving high-quality economic development.Whether corporate social responsibility(CSR),as a key competitive strategy for achieving sustainable economic development,can promote corporate green innovation and the path of evolution has become a hot topic of current research.This paper takes Chinese manufacturing A share listed companies as its sample and uses Stata sofware to conduct regression analysis to test the relationship between CSR,financing constraints,and green innovation,respectively.It further distinguishes the sample into different technological properties and different regions to study the degree of differentiation of the mediating effect on financing constraints.The results show that CSR can not only directly promote corporate green innovation,but that it also can further positively influence corporate green innovation by alleviating financing constraints.Financing constraints play a mediating role in the relationship between CSR and green innovation,especially in enterprises with strong innovation demand and in regions with high levels of regional economic development.The findings enrich the research perspective on the relationship between CSR and green innovation and provide realistic data support for subsequent studies.

竞争约束如何塑造平台相关市场?--基于反垄断案例的质性研究

相关市场界定是平台经济领域反垄断工作的起点和难点。本文基于10个平台市场和98个传统市场的反垄断案例,采用三阶段编码方法,对比分析平台市场和传统市场中从商品的替代性到市场竞争约束的传递路径,构建平台相关市场的竞争约束作用机制模型。研究发现:第一,平台资本是竞争的主体,资本的物质载体差异产生不同的价值增殖模式,在理论上形成不同的相关市场范围。第二,在流通领域,相同的使用价值追逐有限的社会需求,竞争约束表现为商品的替代性。在生产领域,不同的生产过程追逐动态的生产力水平,竞争约束表现为企业的替代性。平台的综合功能、网络效应、产消劳动和市场结构等经济特征使商品和企业的替代性分析更加复杂。第三,市场支配地位是商品的替代性和企业的替代性丧失的结果,垄断企业通过制造市场壁垒维持市场支配地位,制定高于价值的垄断价格,实现垄断利润,因而可以通过潜在竞争者约束这种垄断的市场结构。本文丰富了马克思主义理论的应用场景,为平台经济领域反垄断实务工作提供了学理支撑。

薄壁杆件屈曲模态分析的力特征约束有限条法

整体、畸变、局部等基本变形模式的划分是条理化开展薄壁杆件工程计算的必要手段。薄壁杆件的基本变形模式传统上基于简化应力-应变关系,采用变形、应变等几何特征进行定义,不利于因应复杂化应力-应变关系。提出一套完全基于力特征和正交完备性原则的基本模式定义。与广义梁理论和约束有限条法相比,提出的整体、畸变、局部3种基本变形模式关于刚度严格正交,且完整覆盖薄壁杆件全变形域。基于该定义实现了针对薄壁杆件有限条模型的屈曲模态分解和识别。算例表明,提出的基本模式定义和屈曲模态分析方法具有开、闭口和折、曲线形截面的一致适应能力,剪应变和横向伸缩的影响在基本屈曲模式中得到合理表达,曲线形截面薄壁构件具有与多边形截面薄壁构件一致的整体、畸变和局部屈曲机理。

TOC理论和Witness仿真在汽车产业链整合价值的应用

以某汽车产业链整合企业作为研究对象,以约束理论(TOC)为基础,运用约束理论五步骤法对汽车产业链整合企业进行Witness仿真优化,明显提高了此汽车产业链整合企业的利润收入,达到增加企业价值的目标。

旧工业建筑再生利用关键制约因素研究

科学识别旧工业建筑再生利用的关键制约因素,对促进旧工业建筑再生利用实施及城市可持续更新具有重要意义。首先,通过扎根理论总结11个影响西安市旧工业建筑再生利用的制约因素;然后,采用Fuzzy Decision-Making and Trial Evaluation Laboratory(DEMATEL)方法对制约因素之间的关系进行分析,进而确定影响旧工业建筑再生利用的关键制约因素。结果显示,相应的法律法规缺乏、支持政策不足、旧工业建筑信息不齐全和利益相关者认识不足是西安市旧工业建筑再生利用的关键制约因素。这表明政府在旧工业建筑再生利用发展中扮演至关重要的角色。因此,建议优先采取措施使政府对旧工业建筑再生利用加大重视力度并予以支持,发挥政府的引导作用,逐步推动旧工业建筑的再生利用。

考虑投资不确定性的项目组合选择IGDT模型

受政策的改变以及对新兴领域项目投资缺少足够认知的影响,管理者的项目投资行为往往呈现一定的不确定性。针对企业管理者在进行项目组合投资决策时存在一定风险偏好的情况,本文基于信息间隙决策理论(Information Gap Decision Theory,IGDT),引入净现值偏差系数对管理者的风险偏好进行描述,构建了考虑投资不确定性的项目组合选择新模型。采用包络约束对投资金额不确定性进行描述,给出风险规避与机会寻求两种策略下的项目组合选择IGDT优化模型,并将其转化成单层规划模型进行求解。通过算例仿真,验证了模型的有效性。结果表明:IGDT优化模型不仅满足了管理者投资的预期净现值要求,而且给出了最优的投资金额与项目选择结果。本文构建模型可以为管理者在项目风险管控和资金管理优化方面提供参考。

基于约束理论优化医院互联网诊疗流程的研究

目的:探讨基于约束理论优化医院互联网诊疗就医流程,分析实施效果。方法:选取南通市第一人民医院2022年9月-2023年3月门诊线上线下就诊患者为研究对象。应用约束理论调研分析患者使用医院互联网诊疗平台现状和影响因素,并根据调研结果优化互联网诊疗流程,比较优化前后互联网诊疗平台使用率。结果:流程优化后,互联网诊疗平台使用率由0.39%提高至4.63%;医生接诊响应时间由37.31±4.11降至10.37±3.60分钟;患者互联网医院就诊满意度由79.03±5.16提高至94.89±7.15,差异均有统计学意义(P <0.001)。结论:基于约束理论优化医院互联网诊疗就医流程,可以明显提高互联网诊疗使用率,缩短医生接诊响应时间,提升患者就医体验。

Ashtekar-Kodama Gravity as a Classical and Quantum Extension of Loop Quantum Gravity

This paper presents a new theory of gravity, called here Ashtekar-Kodama (AK) gravity, which is based on the Ashtekar-Kodama formulation of loop quantum gravity (LQG), yields in the limit the Einstein equations, and in the quantum regime a full renormalizable quantum gauge field theory. The three fundamental constraints (hamiltonian, gaussian and diffeomorphism) were formulated in 3-dimensional spatial form within LQG in Ashtekar formulation using the notion of the Kodama state with positive cosmological constant Λ. We introduce a 4-dimensional covariant version of the 3-dimensional (spatial) hamiltonian, gaussian and diffeomorphism constraints of LQG. We obtain 32 partial differential equations for the 16 variables Emn (E-tensor, inverse densitized tetrad of the metric) and 16 variables Amn (A-tensor, gravitational wave tensor). We impose the boundary condition: for large distance the E-generated metric g(E) becomes the GR-metric g (normally Schwarzschild-spacetime). The theory based on these Ashtekar-Kodama (AK) equations, and called in the following Ashtekar-Kodama (AK-) gravity has the following properties. • For Λ = 0 the AK equations become Einstein equations, A-tensor is trivial (constant), and the E-generated metric g(E) is identical with the GR-metric g. • When the AK-equations are developed into a Λ-power series, the Λ-term yields a gravitational wave equation, which has only at least quadrupole wave solutions and becomes in the limit of large distance r the (normal electromagnetic) wave equation. • AK-gravity, as opposed to GR, has no singularity at the horizon: the singularity in the metric becomes a (very high) peak. • AK-gravity has a limit scale of the gravitational quantum region 39 μm, which emerges as the limit scale in the objective wave collapse theory of Gherardi-Rimini-Weber. In the quantum region, the AK-gravity becomes a quantum gauge theory (AK quantum gravity) with the Lie group extended SU(2) = ε-tensor-group(four generators) as gauge group and a corresponding covariant derivative. • AK quantum gravity is fully renormalizable, we derive its Lagrangian, which is dimensionally renormalizable, the normalized one-graviton wave function, the graviton propagator, and demonstrate the calculation of cross-section from Feynman diagrams.

企业管理柔性的形成机理与测量——基于创造力约束理论的扎根研究

新时代背景下管理方式变革是企业适应复杂环境变化的重要手段。事实上,大多数企业管理方式变革源于外部环境变化和内部创新实践,而非事先规划。因此,企业如何突破约束,实现自主变革到管理柔性实践的实质性跨越,是当前理论界和实践界共同的管理热点问题之一。文章从创造力约束理论视角,运用扎根理论方法对34篇文献进行剖析,分析了企业管理柔性的形成机制,并构建了测量模型。编码结果发现:企业管理柔性在形成过程中会面临不同的约束,需要识别形成过程中关键的约束情景,只有认识外部环境的复杂变化与企业现有管理方式僵化之间的矛盾,并采取相应策略,才能推进管理柔性的实施;同时,企业组织结构管理柔性、人力资源柔性、项目管理柔性和供应链管理柔性是实施柔性管理的重要内容。文章在理论上厘清了企业管理柔性的形成机理和管理内容,揭示了员工创新需求推动组织管理方式变革的过程,为激发员工创新活力提供了管理启示。

多蛇形机器人编队路径跟踪控制

为了实现多个蛇形机器人的编队控制,该文提出一种基于误差约束的抗干扰路径跟随方法。该方法使用高度耦合的动态频率补偿器来调整每个机器人的运动速度,以确保编队成员之间位置和速度的一致性。在动力学控制中,通过障碍函数的等效原则消除了虚拟变量的奇异现象,提高了路径跟随的稳定性。此外,该文设计了模型不确定性和外界干扰的预测值,以此来提前补偿机器人的关节偏移量和扭矩输入,从而进一步提高了跟随误差的收敛速度和稳态性能。最后,利用Lyapunov理论证明了该方法的一致最终有界性(UUB)。仿真数据表明,相对于其他经典方法,该文所提模型和控制策略具有更高的跟随精度。

埋地压力管道在敷设方向改变时考虑曲管段侧向约束的受力分析

埋地压力管道在敷设方向改变处,由于液体压力引起的推力一般与曲管段侧向抗力、直管段侧向土壤抗力和轴向摩擦力等三种抗力相互平衡。本文基于欧拉-伯努利梁理论和温克尔地基梁模型,以带刚性接口的、水平转向的埋地压力管道为研究对象,推导出在上述抗力同时作用的情况下直管段有效约束长度的解析解。对比研究了是否考虑曲管段范围土的侧向刚度对管道的内力、位移的影响,分析了管-土摩擦系数、敷设方向改变角度、直管段土侧向刚度、曲管段侧向约束等因素对管道有效约束长度、弯矩、轴向力和剪力的影响。本文推导的解析解可以根据直管和曲管侧向约束更合理地计算管道有效约束长度。

一种基于自适应边界约束的高效遗传算法

针对遗传算法中用于多父体重组的系数向量缺乏高效生成方法的问题,提出一种基于自适应边界约束(ABC)的高效遗传算法。该方法依据前一个系数的值,自适应缩放后一个系数的边界,可在任意多的父代重组情形下快速生成系数向量。在CEC2017标准数据集上的实验结果表明,所提算法在29个复杂优化问题上的表现都优于经验概率分布(EDBF)算法。

第三方检测机构失范行为的发生机理与治理路径研究

近年来,作为政府监管补充的第三方检测频频出现行为失范问题。基于委托代理理论视角,发现第三方检测机构失范行为的发生与其行为被识别的难易程度、行为收益和行为成本等因素紧密相关。第三方检测机构失范行为发生的原因主要有行为识别不足、整体收益考量以及成本管理薄弱等。据此,应建立引导第三方检测机构选择规范行为的激励约束制度,包括:政府监督和社会监督相结合,强化行为识别机制;直接激励和间接激励相结合,健全收益提升机制;实现放管结合,建立成本控制机制。

互联网贷款助力解决中小微企业融资难问题

互联网贷款具有渠道、效率、成本和信息四方面优势,与中小微企业具有天然的协同合作优势。基于“长尾”理论的基础,通过对互联网这一中介缓解中小微企业融资难题的可行性进行分析,可以得到:中小微企业作为融资的长尾,互联网的存在就成了中小微企业融资难的救星。但是,互联网贷款的发展也存在技术风险、信用风险、法律风险等传统风险,这就需要通过创新管控技术提升风控的能力和建立征信系统,提高服务效率等多措并举,切实帮助中小微企业解决融资难题。

基于时空库普曼自动编码器的风电场短期风速预测

为了提升以新能源为主体的新型电力系统的风电消纳水平,需要对风速进行精确预测,关键在于提炼风电系统动态趋势与风速序列中潜在的物理结构。依据库普曼动力学理论与自编码器思想搭建物理约束时空神经网络,生成风电场非线性变量的线性演化矩阵。首先,通过线性演化矩阵近似系统趋势,在预测过程中充分考虑前、后向动态。然后,设置双向相关预测机制与适配不同对象的代价函数,降低预测对序列的可逆性、平稳性要求。同时,对特征空间隐向量进行可视化,展现系统内特征区间依赖。最后,借助北票王子山风电场风速实测数据验证所提方法的有效性。结果表明:所提方法对于强随机、强波动的风速序列具有较高的预测精度,泛化能力强,可解释性优越。

NEW BIFURCATION PATTERNS IN ELEMENTARY BIFURCATION PROBLEMS WITH SINGLE-SIDE CONSTRAINT

Bifurcations with constraints are open problems appeared in research on periodic bifurcations of nonlinear dynamical systems, but the present singularity theory doesn't contain any analytical methods and results about it. As the complement to singularity theory and the first step to study on constrained bifurcations, here are given tire transition sets and persistent perturbed bifurcation diagrams of 10 elementary bifurcation of codimension no more than three.