Simulation of anchor chain based on lumped mass method

In order to develop a anchoring operation simulation system and improve safety during anchoring operations,a relatively accurate mathematical model of anchoring operations needs to be established.In this paper,the stress condition of anchor chain under environmental and subsea geological conditions is further studied and the stress condition of anchor chain is analyzed based on the previous research.In this paper,a quasi-static model based on catenary method is used as the basis of dynamic analysis,and the dynamic model of anchor chain is established based on the concentrated mass method,which fully considers the influence of anchor chain weight,hydrodynamic force,ocean current and interaction with the seabed.The fourth-order Runge Kutta method was used to solve the model numerically,and a calculation procedure was developed.The accuracy of the model was verified by comparing the calculated results with the experimental results,indicating that the constructed anchor chain dynamics model has a high accuracy.

Nonlinear wave dispersion in monoatomic chains with lumped and distributed masses:discrete and continuum models

The main objective of this paper is to investigate the influence of inertia of nonlinear springs on the dispersion behavior of discrete monoatomic chains with lumped and distributed masses.The developed model can represent the wave propagation problem in a non-homogeneous material consisting of heavy inclusions embedded in a matrix.The inclusions are idealized by lumped masses,and the matrix between adjacent inclusions is modeled by a nonlinear spring with distributed masses.Additionally,the model is capable of depicting the wave propagation in bi-material bars,wherein the first material is represented by a rigid particle and the second one is represented by a nonlinear spring with distributed masses.The discrete model of the nonlinear monoatomic chain with lumped and distributed masses is first considered,and a closed-form expression of the dispersion relation is obtained by the second-order Lindstedt-Poincare method(LPM).Next,a continuum model for the nonlinear monoatomic chain is derived directly from its discrete lattice model by a suitable continualization technique.The subsequent use of the second-order method of multiple scales(MMS)facilitates the derivation of the corresponding nonlinear dispersion relation in a closed form.The novelties of the present study consist of(i)considering the inertia of nonlinear springs on the dispersion behavior of the discrete mass-spring chains;(ii)developing the second-order LPM for the wave propagation in the discrete chains;and(iii)deriving a continuum model for the nonlinear monoatomic chains with lumped and distributed masses.Finally,a parametric study is conducted to examine the effects of the design parameters and the distributed spring mass on the nonlinear dispersion relations and phase velocities obtained from both the discrete and continuum models.These parameters include the ratio of the spring mass to the lumped mass,the nonlinear stiffness coefficient of the spring,and the wave amplitude.

Seismic fluid identification using a nonlinear elastic impedance inversion method based on a fast Markov chain Monte Carlo method

Elastic impedance inversion with high efficiency and high stability has become one of the main directions of seismic pre-stack inversion. The nonlinear elastic impedance inversion method based on a fast Markov chain Monte Carlo （MCMC） method is proposed in this paper, combining conventional MCMC method based on global optimization with a preconditioned conjugate gradient （PCG） algorithm based on local optimization, so this method does not depend strongly on the initial model. It converges to the global optimum quickly and efficiently on the condition that effi- ciency and stability of inversion are both taken into consid- eration at the same time. The test data verify the feasibility and robustness of the method, and based on this method, we extract the effective pore-fluid bulk modulus, which is applied to reservoir fluid identification and detection, and consequently, a better result has been achieved.

Forecasting Methods to Reduce Inventory Level in Supply Chain

Based on the two-level supply chain composed of suppliers and retailers, we assume that market demand is subject to an ARIMA(1, 1, 1). The supplier uses the minimum mean square error method (MMSE), the simple moving average method (SMA) and the weighted moving average method (WMA) respectively to forecast the market demand. According to the statistical properties of stationary time series, we calculate the mean square error between supplier forecast demand and market demand. Through the simulation, we compare the forecasting effects of the three methods and analyse the influence of the lead-time L and the moving average parameter N on prediction. The results show that the forecasting effect of the MMSE method is the best, of the WMA method is the second, and of the SMA method is the last. The results also show that reducing the lead-time and increasing the moving average parameter improve the prediction accuracy and reduce the supplier inventory level.

SEMI-BLIND CHANNEL ESTIMATION OF MULTIPLE-INPUT/MULTIPLE-OUTPUT SYSTEMS BASED ON MARKOV CHAIN MONTE CARLO METHODS

This paper addresses the issues of channel estimation in a Multiple-Input/Multiple-Output (MIMO) system. Markov Chain Monte Carlo (MCMC) method is employed to jointly estimate the Channel State Information (CSI) and the transmitted signals. The deduced algorithms can work well under circumstances of low Signal-to-Noise Ratio (SNR). Simulation results are presented to demonstrate their effectiveness.

Adding Sub-chain Method for Structural Synthesis of Planar Closed Kinematic Chains

For at least the past five decades,structural synthesis has been used as a main means of finding better mechanisms with some predefined function.In structural synthesis,isomorphism identification is still a problem unsolved well,and to solve this problem is very significant to the design of new mechanisms.According to the given degree of freedom（DOF） and link connection property of planar closed chain mechanisms,vertex assortment is obtained.For solving the isomorphism problem,a method of the adding sub-chains is proposed with the detailed steps and algorithms in the synthesizing process.Employing this method,the identification code and formation code of every topological structure are achieved,therefore many isomorphic structures could be eliminated in time during structural synthesis by comparing those codes among different topological graphs,resulting in the improvement of synthesizing efficiency and accuracy,and the approach for eliminating rigid sub-chains in and after the synthesizing process is also presented.Some examples are given,including how to add sub-chains,how to detect simple rigid sub-chains and how to obtain identification codes and formulation codes et al.Using the adding sub-chain method,the relative information of some common topological graphs is given in the form of table.The comparison result is coincident with many literatures,so the correctness of the adding sub-chain method is convinced.This method will greatly improve the synthesizing efficiency and accuracy,and has a good potential for application.

INCOMPLETE SEMI-ITERATIVE METHODS FOR SOLVING SINGULAR LINEAR OPERATOR EQUATIONS IN BANACH SPACE WITH APPLICATIONS IN MARKOV CHAIN MODELING

We discuss the incomplete semi-iterative method (ISIM) for an approximate solution of a linear fixed point equations x=Tx+c with a bounded linear operator T acting on a complex Banach space X such that its resolvent has a pole of order k at the point 1. Sufficient conditions for the convergence of ISIM to a solution of x=Tx+c, where c belongs to the range space of R(I-T) k, are established. We show that the ISIM has an attractive feature that it is usually convergent even when the spectral radius of the operator T is greater than 1 and Ind 1T≥1. Applications in finite Markov chain is considered and illustrative examples are reported, showing the convergence rate of the ISIM is very high.

AUTOMATIC DISPLACEMENT ANALYSIS OF PLANAR MECHANISMS WITH MATCHING BASIC KINEMATIC CHAINS METHOD

A simple, efficient, automatic and universal method to fulfill displacementanalysis of a great deal of mechanisms regenerated by Yan's mechanism creative theory has beendeveloped. For a regenerated mechanism, at first, the method identifies its type and structure andchanges it into a rigid structure by fixing the ground link and the input link. And then this rigidstructure is decomposed into a set of basic kinematic chains (BKCs). By matching the type of BKC,the displacement analysis equations can be set up, and all possible configurations, in whichpositions of all movable links are considered, can be given out.

Deriving Vibration Modes of Semi-infinite Chain Model by “Invariant Eigen-operator”Method

For the first time, we introduce a fully quantum mechanical Hamiltonian for a semi-infinite chain model of atoms. We then derive the vibration modes of this model by virtue of the ＂invariant eigen-operator＂ method in two different cases, which is concise and revealing.

Energy Level of Coupled Harmonic Oscillator Model Born of Heisenberg Ferromagetic Spin Chain Derived by Invariant Eigen-operator Method

Based on the coupled harmonic oscillator model, which is born of Heisenberg ferromagnetic spin chain with nearest-neighbor interactions, we adopt the invariant eigen-operator method to derive its energy level, which provides an alternate approach to dealing with the dynamics of spin chain.

A review of arc-discharge method towards large-scale preparation of long linear carbon chains

Linear carbon chains as new one-dimensional(1D)nanomaterials attract attention for the predicted outstanding properties.However,the high reactivity of linear carbon chains hampers further experimental research.To date,different methods have been developed to synthesize new materials containing linear carbon chains.Among them,the arc-discharge method is a practical way to prepare both finite and infinite linear carbon chains.This review provides a brief discussion of the recent progress in the techniques to prepare carbon chain-based materials and then focuses on the arc-discharge method.The configuration of apparatus,optimal conditions,and the corresponding mechanism of arc-discharge method to prepare long linear carbon chain inside multi-walled carbon nanotubes are summarized in detail.The characterization techniques are introduced to evaluate the quality of products.Moreover,remaining challenges and perspectives are presented for further investigation of long linear carbon chains.

Optimum Design of Stair-Climbing Robots Using Taguchi Method

Environmental issues like pollution are major threats to human health.Many systems are developed to reduce pollution.In this paper,an optimal mobile robot design to reduce pollution in Green supply chain management system.Green supply chain management involves as similating environmentally and eco-nomically feasible solutions into the supply chain life-cycle.Smartness,advanced technologies,and advanced networks are becoming pillars of a sustainable supply chain management system.At the same time,there is much change happening in the logistics industry.They are moving towards a new logistics model.In the new model,robotic logistics has a vital role.The reasons for this change are the rapid growth of the e-commerce business and the shortage of workers.The advantages of using robotic logistics are reduction in human errors,faster delivery speed,better customer satisfaction,more safety for workers,and high workforce adaptability.A robot with rocker-bogie suspension is a six-wheeled mobile platform that has a distinctive potential to keep all wheels on the ground continuously.It has been designed to traverse rough and uneven terrain by distributing the load over its wheels equally.However,there is a limitation to achieving high-speed mobility against vertical barriers.In this research,an optimal design of product delivery wheeled robots for a sustainable supply chain system is proposed to ensure higher adaptability and maximum stability during climbing staircases.The design parameters of the proposed robot are optimized using Taguchi Method.The aim is to get a smooth trajectory of the robot’s center-of-mass.The proposed approach realizes a robot with much-improved stability which can climb over heights more than the size of the wheel(i.e.,3 times the radius of wheels).The results reveal that the modified rocker-bogie system not only increases the stair-climbing capability but also thwarts instability due to overturning of a wheel of the robot.

A Study on the Factors Influencing Value-Added in the Cruise Ship Value Chain Based on the DEMATEL-ISM Model

Cruise value chain is to take the exchange of cruise products and services as the core in a certain spatial scope,and enterprises with core advantages within or between different industries establish associations in accordance with certain technical and economic conditions,so as to realise the multi-dimensional extension and value appreciation of the cruise value chain in the vertical and horizontal links,and ultimately establish a chain-network type of enterprise strategic alliance.This paper tries to analyse the value-added factors of the cruise industry chain by constructing a multi-level hierarchical structural model with reference to the influencing factor analysis methods of relevant literature-DEMATEL(Decision Making Experiment and Evaluation Experiment)and ISM(Interpretative Structural Model).The study shows that the innovation and scale value-added module in the upstream of the cruise industry chain is the core module of value-added of the whole cruise industry chain,and the value-added mainly originates from the design and manufacturing of cruise ships.The middle reaches of the cruise industry chain are mainly cruise operation enterprises,and the specificity of cruise operation determines that its brand value-added is mainly accomplished through the global layout of multinational corporations,and the cruise brand is able to drive the consumption demand and has value-added ability.The downstream value-added of the cruise industry chain is mainly realised through the increase in profits of cruise tourism service products.

中国数字经济发展水平的地区差异、空间集聚与状态转移

文章基于TOPSIS法,通过CRITIC权与灰色关联理论构建CRITIC权灰色关联TOPSIS法,并将其在空间与时间上应用两次,从而可对面板数据进行短期评价。根据新评价法测算2015—2020年中国31个省份的数字经济发展水平并展开分析,结果显示:中国数字经济发展水平地区差异显著,主要取决于三大地区间的差异,且有扩大趋势;北京、上海稳居前2名,浙江、广东、福建、天津、江苏稳居第3至第7名;贵州、青海数字经济发展进步较大,东北三省排名退步显著;省域数字经济发展水平状态转移较难,跨级状态转移基本不会发生,较低水平状态为贫困陷阱,陷于其中的省份很难靠自身得到提升;中国数字经济发展水平存在空间集聚现象,基于配对t检验的结果表明,数字经济可以在一定程度上打破地理限制。

现代产业链韧性评价及提升路径

国际变局加剧产业链发展风险,产业链韧性是建设现代化产业体系和提升产业链安全的重要基础。理解产业链韧性的内涵及影响因素是建立产业链韧性理论分析的基础,构建包括产业链基础能力、产业链抵御能力、产业链链条控制力和产业链创新能力在内的多维评价指标体系,通过熵值法对产业链韧性水平进行测度评价,并与美国、日本、印度等国家进行国际比较。研究发现,支撑中国产业链韧性的主要因素是包括基础设施、劳动力供给在内的产业链基础能力。与发达国家相比,产业链抵御能力和产业链创新能力对产业链韧性提升的贡献相对较低;近年来中国产业链韧性水平总体呈现上升趋势,但是增速放缓。因此,应该加快关键核心技术攻关的产业链创新能力,提升产业链治理能力,积极开展高水平对外开放和推动产业链数字化转型,成为提升中国产业链韧性的主要政策主张。

基于DEMATEL-ISM方法的水电站机组检修作业安全事故致因链分析

针对水电站机组检修作业种类和危险因素多、安全事故频发等问题,通过文献挖掘与专家访谈方式,对水电站机组检修作业安全影响因素类别进行了划分。基于DEMATEL-ISM方法,构建了安全事故致因多层次递阶ISM模型来确定事故致因因素层级,通过剖析事故致因因素的中心度和权重,挖掘关键致因因素和推求事故致因链的路径权重,厘定关键致因链。采用该模型对某水电站致因链进行了分析,结果表明,安全检查不到位为关键致因因素,“安全检查不到位→违规作业→设备的问题→粉尘、油漆等有害物质”为关键致因链。

新质生产力三维创新生态系统及水平测度分析

新质生产力是由技术颠覆性突破、生产要素创新性配置、产业深度转型升级而催生的当代先进生产力;一切利用新技术提升生产力水平驱动高质量发展的领域,都属于新质生产力的应用范畴。从创新生态系统角度构建新质生产力的评价指标体系,利用熵值法、Kernel密度估计法和空间Markov链法进行实证分析。研究结论如下:首先,新质生产力在微观层面表现为新质人才、新质生产单元和新质企业组织;在中观层面表现为新质产业部门、新质产业链、新质创新网络、新质产业集群;在宏观层面表现为国家科技创新政策体系。其次,基于新质生产力的三个维度,构建新质生产力的综合指标体系,通过熵值法测度发现,中国新质生产力总体水平较低,但呈逐年增长趋势,东部地区新质生产力水平远高于中部、西部和东北地区。最后,利用Kernel密度估计法和空间Markov链法分析可知,新质生产力发展不均衡问题较为凸显,空间效应也是影响新质生产力发展的重要因素。

数字经济背景下智慧供应链发展水平测度——以长江经济带为例

物联网、云计算及大数据等技术的深度融合促进了数字经济的发展,也促进了区域智慧供应链的发展。长江经济带是连接东西部的重要区域,其智慧供应链的发展水平是判断其良性发展的重要依据。为此文章基于数字经济背景,从资源、输出和柔性三个维度构建了长江经济带智慧供应链发展水平评价体系,采用博弈论组合赋权法确定各指标权重,测算了长江经济带11省(市)2016年至2021年智慧供应链发展水平,运用系统聚类分析法和马尔科夫链统计分析方法探索了长江经济带智慧供应链的时空特征及未来发展趋势,并根据分析结果对其智慧供应链发展提出相应的建议。

基于云模型的“一带一路”沿线省份国际冷链物流发展水平评价研究

在全球消费需求日益扩大的背景下,冷链产品进出口量剧增,为冷链物流提供新的发展机遇。为研究区域间国际冷链物流发展水平差异,考虑营商环境和地理因素,构建国际冷链物流发展水平评价指标体系,运用熵权-云模型对国际冷链物流发展水平进行评价,以“一带一路”沿线省份为例进行实证分析。结果表明:71%的省份国际冷链物流发展水平处于中上水平。在营商环境、基础设施和地理环境方面存在发展差异,其中进出口总额、冷藏车数、国际联系强度和对外开放水平是影响发展的主要因素。空间上,沿海省份国际冷链物流发展水平高于内陆省份,北部地区呈现“一核一副,周边聚集”的特征,东南沿海地区呈带状分布,西北地区呈现“中部低,两端高”的特征。

基于视觉信息加工的草原公路行车安全性分析

为探究草原公路各典型行车环境驾驶人视觉信息加工模式的差异性,从视觉层面解析草原公路行车安全,基于眼动仪开展草原公路实车实验,提取驾驶人在自由行驶、跟驰、对向来车、后车切入、路侧风险、交叉口6种真实行车环境下的眼动数据。首先,从视觉分配和视觉搜索两个维度构建评价指标体系,采用动态聚类法将驾驶人的视觉兴趣区域划分为5类,将信息熵与马尔可夫链平稳分布理论结合,构建视点分布信息熵量化驾驶人视觉注意分配的复杂度,并引入扫视幅度、扫视速度分析驾驶人对视觉信息的搜索过程。最后,构建基于CRITIC法的加权秩和比评价模型,对不同行车环境下驾驶人的视觉信息加工强度进行了综合评价。结果显示:驾驶人的视点分布在不同行车环境中存在差异,但当前车道始终是驾驶人获取视觉信息的主视区;各视觉评价指标随行车环境的变化呈显著的统计学差异;驾驶人遇到路侧风险时的视觉信息加工强度最大,行车安全性相对更低。