Deterministic and Stochastic Fractional-Order Hastings-Powell Food Chain Model

In this paper,a deterministic and stochastic fractional-order model of the tri-trophic food chain model incorporating harvesting is proposed and analysed.The interaction between prey,middle predator and top predator population is investigated.In order to clarify the characteristics of the proposed model,the analysis of existence,uniqueness,non-negativity and boundedness of the solutions of the proposed model are examined.Some sufficient conditions that ensure the local and global stability of equilibrium points are obtained.By using stability analysis of the fractional-order system,it is proved that if the basic reproduction number R_(0)<1,the predator free equilibrium point E_(1) is globally asymptotically stable.The occurrence of local bifurcation near the equilibrium points is investigated with the help of Sotomayor’s theorem.Some numerical examples are given to illustrate the theoretical findings.The impact of harvesting on prey and themiddle predator is studied.We conclude that harvesting parameters can control the dynamics of the middle predator.A numerical approximation method is developed for the proposed stochastic fractional-order model.

Dynamics of an autonomous food chain model and existence of global attractor of the associated non-autonomous system

In this paper,we have analyzed a tri-trophic food chain model consisting of phytoplankton,zooplankton and fish population in an aquatic environment.Here,the pelagic water column is divided into two layers namely,the upper layer and the lower layer.The zooplankton population makes a diel vertical migration(DVM)from lower portion to upper portion and vice-versa to trade-off between food source and fear from predator(Fish).Here,mathematical model has been developed and analyzed in a rigorous way.Apart from routine calculations like boundedness and positivity of the solution,local stability of the equilibrium points,we performed Hopf bifurcation analysis of the interior equilibrium point of our model system in a systematic way.It is observed that the migratory behavior of zooplankton plays a crucial role in the dynamics of the model system.Both the upward and downward migration rates of DVM leads the system into Hopf bifurcation.The upward migration rate of zooplankton deteriorates the stable coexistence of all the species in the system,whereas the downward migration rate enhance the stability of the system.FYirther,we analyze the non-autonomous version of the system to capture seasonal effect of environmental variations.We have shown that under certain parametric restrictions periodic coexistence of all the species of our system is possible.Finally,extensive numerical simulation has been performed to support our analytical findings.

Numerical solution of time-fractional three-species food chain model arising in the realm of mathematical ecology

T'his research paper implements the fractional homotopy analysis transform technique to compute the approximate analytical solution of the nonlinear three-species food chain model with time-fractional derivatives.The offered technique is a fantastic blend of homotopy analysis method(HAM)and Laplace transform(LT)operator and has been used fruitfully in the numerical computation of various fractional differential equations(FDEs).This paper involves the fractional derivatives of Caputo style.The numerical solutions of this selected fractional-order food chain model are evaluated by making use of the associated initial conditions.It is revealed by the adopting procedure that the more desirable estimation of the solution can be easily acquired through the calculation of some number of iteration terms only-a fact which authenticates the easiness and soundness of the suggested hybrid scherne.The variations of fractional order of time derivative on the solutions for different specific cases have been depicted through graphical presentations.The outcomes demonstrated through the graphs expound that the adopted scheme is very fantastic and accurate.

A DYNAMIC FOOD CHAIN MODEL FOR HONG KONG BASED ON RADFOOD MODEL AND BIRCHALL－JAMES ALGORITHM

In this paper a dynamic food chain model for Hong Kong which simulates the transfer of radioactive substances from a fallout deposition via the food chain into the human bodies is built. The model is based on the RADFOOD model and the BirchallJames algorithm. The radionuclides 13if and 90Sr representing the short-term and long-term risk situations have been studied as sample cases. Various types of crops,and the dietary pattern of the public have been collsidered. The resulting internal radiation doses have been calculated. The results are obtained for food consumption starting at various time after the fallout deposition and for different consumption durations.

OVERTAKING OPTIMAL HARVESTING FOR AN AGE-DEPENDENT n-DIMENSIONAL FOOD CHAIN MODEL

This paper is concerned with an optimal harvesting problem over an infinite horizon for age-dependent n-dimensional food chain model and the analysis of long-term behaviors of the optimal-controlled system. The existence of overtaking optimal policy is proved and a maximum principle is carefully derived by means of Dubovitskii-Milyutin functional analytical extremum theory. Weak and strong turnpike properties of optimal trajectories are established.

A dynamic food-chain model and program for predicting the consequences of nuclear accident

A dynamic food chain model and program, DYFOM 95, for predicting the radiological consequences of nuclear accident has been developed, which is not only suitable to the West food chain but also to Chinese food chain. The following processes, caused by accident release which will make an impact on radionuclide concentration in the edible parts of vegetable were considered: dry and wet deposition interception and initial retention, translocation, percolation, root uptake and tillage. Activity intake rate of animals, effects of processing and activity intake of human through ingestion pathway ware also considered in calculations. The effects of leaf area index LAI of vegetable were considered in dry deposition model. A method for calculating the contribution of rain with different period and different intensity to total wet deposition was established. The program contains 1 main code and 5 sub codes to calculate dry and wet deposition on surface of vegetable and soil, translocation of nuclides in vegetable, nuclide concentration in the edible parts of vegetable and in animal products and activity intake of human and so on.

粮食供应链韧性影响因素及提升策略研究

粮食供应链韧性关乎粮食安全,探究粮食供应链韧性的影响因素具有现实意义。基于文献研究法和专家访谈法,从预测能力、抵抗能力、恢复能力、成长能力4个维度确定影响粮食供应链韧性的20个重要因素,构建DEMATEL-ISM综合模型并绘制ISM层级结构图。在探究各因素对粮食供应链韧性的重要程度和影响力大小的基础上,识别其关键影响因素,并利用ISM将各因素划分层级,明晰各要素之间的相互作用关系。结果表明:政策支持、政策与市场变动、信息共享能力、数字技术应用与创新4个因素是粮食供应链韧性的关键影响因素,也是最深层的根本因素。预测能力和成长能力会对粮食供应链韧性的抵抗能力和恢复能力产生影响,是韧性能力的基础,对粮食供应链韧性起直接作用。该研究结论为我国粮食供应链韧性提升提供了针对性建议。

我国出口食材供应链现状分析与趋势展望

本文以我国出口食材贸易环境为切入点,详细梳理了全球经济和食材贸易格局及消费情况,着重剖析了我国出口食材供应链模式的现状、机遇与挑战,并预测了未来的发展方向与趋势。

基于跨链技术的食品供需网信息共享激励模式构建

随着食品种类多元化和消费者需求的提升,食品生产流程更加复杂,供应链之间交流越来越多,相关企业、食品供应链和行业机构之间的交互形成了复杂的食品供需网结构。食品供需网成员之间信息共享有利于企业之间充分合作实现长期发展,但仍有许多企业共享信息意识较弱,无法进行有效信息沟通。区块链跨链技术的应用和发展,为食品供需网信息共享提供了新思路。根据食品供需网复杂性,引入区块链技术和声誉激励机制,将声誉进行量化管理,结合区块链智能合约技术实现声誉激励机制自动化。进一步引入区块链跨链技术,打破不同行业、地区区块链之间的交易壁垒,构建基于区块链跨链技术的食品供需网信息共享声誉激励模式,以猪肉供需网为例阐述跨链信息共享声誉激励流程。该激励模式不仅保障共享信息安全性与准确性,同时保护企业隐私,最大程度保护交易方自身利益,破解信息无法共享的障碍,激发食品供需网企业参与信息共享积极性。不仅实现食品供需网内部异构区块链之间的信息交流和价值互通,还为食品供需网价值信息交流互通的发展提供新思路。

一类三物种食物链模型解的全局存在性

在生态学中,三物种食物链模型是一类极其重要的模型,它能够描述食饵、中间捕食者和高级捕食者之间的相互作用与数量随时间、空间变化规律。主要考虑了一类具有非线性趋食敏感函数的食物链模型,在齐次Neumann边界条件下,当模型中的初值和参数都满足一定条件时,利用抛物方程正则性理论及必要的先验估计,得到在高维情形下该模型解的全局存在性。

食品供应链中的数学建模与优化研究

通过概述食品供应链的基本构成及数学建模在其中的作用,介绍常用的库存模型、运输模型和生产计划模型。在此基础上,识别供应链效率优化、成本控制与优化以及食品安全与质量控制等关键问题,提出相应的数学建模与优化策略。通过构建流程优化模型、成本优化模型以及风险评估模型,为食品供应链的优化提供了理论支持和实践指导。

“从农田到餐桌”全链条食品质量与安全管理策略分析

加强“从农田到餐桌”全过程安全与质量管理是进一步加强食品控制,提升食品安全与质量水平的关键举措。“从农田到餐桌”的过程,就是食品从生产到销售、食用的过程,这一系列过程中存在较多质量与安全影响因素,若不加以控制,不仅会增加食品质量风险,也会对消费者生命健康造成威胁,不利于社会和谐稳定发展。本文分析了塑造“从农田到餐桌”全链条管理体系的必要性,立足全链条视域下分析食品质量与安全影响因素,并分别从全链条食品质量与安全管理的顶层设计、分环节优化入手,提出一系列管理策略。

质量链角度下食品质量管理模式研究

质量链作为一个综合性的管理系统,强调了从原料采购到产品销售的每一个环节的质量控制与协调。在食品质量管理中,质量链的引入不仅提高了产品质量的可追溯性,还有助于实现全过程的监管与控制。本文分析了质量链角度下食品质量管理模式的重要性,以及当前食品质量管理面临的挑战,提出了质量链角度下食品质量管理模式的构建策略,旨在为食品企业提供一种以质量链为核心的质量管理模式,促进食品行业的健康发展,保障消费者的饮食安全,为监管部门提供决策参考,推动食品质量管理的创新与完善。

基于改进DIIM的洪涝灾害下供应链系统中断关联型损失评估研究

为解决暴雨洪涝灾害频发对企业生产和整条供应链的运行带来的巨额经济损失问题,在考虑供应链系统相互关联的基础上,运用改进的动态非正常程度投入产出模型(DIIM)模拟洪涝灾害导致企业非正常程度的动态运行状态,测算洪涝灾害给供应链系统带来的直接损失及关联损失。以2021年马来西亚洪涝灾害影响下的某制造业供应链系统为例,选取相关指标对洪涝灾害导致供应链系统中断带来的关联型损失进行评估。结果表明:洪涝灾害引发的供应链各节点功能下降程度由需求端和供应端两方干扰共同影响,非正常程度和损失都是一个动态变化的过程;仿真数据直观显示了洪涝灾害下供应链中断发生、扩散及恢复过程,有助于决策者对洪涝灾害下供应链系统运行进行分析和管理。

具有变时滞随机三种群食物链模型的渐近行为

本文研究了一类具有变时滞随机三种群食物链模型。利用Razumikhin和Lyapunov方法,讨论了该模型全局正解的存在性和渐近性,给出了该模型一阶矩实用指数稳定和指数稳定性的充分条件。通过数值模拟说明了理论的有效性。

农产品供应链韧性网络影响因素研究——基于复杂系统管理视角

基于复杂系统管理视角,从农产品供应链生产者、收购商、批发商、零售商、消费者及流通环节识别并筛选出20个农产品供应链韧性网络影响因素,构建DEMATEL-ISM模型,通过分析各影响因素间作用强度确定关键性因素,并对影响因素进行层级划分,厘清各因素间的逻辑结构关系。研究结果表明,信息流通能力为农产品供应链韧性的根本影响因素;产销达标能力、收购商定价议价能力、批发商定价议价能力、销售商营销能力直接影响农产品供应链韧性。

供应链金融视角下食品企业发展模式研究

食品产业供应链环节多、流通周期长、产业关联广,纵向和横向上都具有多个维度,为供应链金融提供了便利。然而,随着科技水平的提高,人力成本的提高,食品企业的利润空间越来越小,企业的经营规模越来越小,风险防范能力也随之变弱,难以靠自己的信用来获得高质量的信贷,从而导致了企业经营效率的下降,导致我国的食品企业普遍面临着融资困难的问题。供应链金融的兴起给传统的食品企业带来了新的融资模式,同时也提供了一种新的发展模式与筹资战略,因而有必要从供应链金融的角度来探讨食品企业的发展模式。

食品供应链领域企业区块链技术采纳行为整合模型构建研究

企业采用率低、缺乏行业级大规模应用是当今食品供应链领域区块链技术应用面临的突出问题,整合现有碎片化的研究,提供一个更具系统性的企业区块链技术采纳行为模型,既能为学界深入探究和理解企业区块链技术采纳行为提供理论支持,也能为企业推进区块链项目实施决策提供参考。本文通过回顾和梳理国内外相关研究,集成行为推理理论、技术-组织-环境框架、创新扩散及社会资本等理论的核心观点,构建了食品供应链领域企业区块链技术采纳行为的整合模型,理论化、规范化阐述了影响企业区块链技术采纳意向的前置因素。模型显示,企业基于技术特征、组织特征、环境特征3维度下23项推动型与限制型因素的推理判断,形成技术采纳意向,驱动技术采纳行为。据此,企业应以强化推动型因素影响和防范限制型因素影响为重点,更有效地推进区块链技术的采纳与实施。

生鲜电商冷链装配优化:提高物流效率与服务质量的研究

生鲜电商行业得益于方便快捷的服务特性与电商技术的支持,近年来发展迅猛,市场交易额逐年攀升。但与之矛盾的是,运输冷链商品所需冷链物流装配服务未能达到企业目标,在出库包装上,生鲜企业缺乏科学的模型支持决策,依据经验添置冰袋数目,导致成本高昂。本文研究了生鲜电商食品冷链耗材装配优化问题,通过建模求解等过程为冷链运输场景下的食品包装提供优化方案,在满足生鲜流通温度区间的条件下,使包装耗材总成本最小,调和了企业成本与用户满意度之间的矛盾,为企业提供理论依据和实践参考标准。

新零售模式下叮咚买菜供应链管理优化路径——基于SCOR模型的分析研究

近年来,随着新冠疫情的爆发和电商行业的兴起,生鲜电商市场规模逐步扩大。由于生鲜产品本身存在着难保存、易损坏的特点,传统物流难以满足其特殊需求。文中在新零售商业模式的背景下,基于SCOR模型,通过研究生鲜电商平台供应链管理现状,分析叮咚买菜供应链管理存在的问题,并从计划、采购、生产、配送、退货五个环节为企业提供优化措施,以供我国生鲜电商企业参考。