A Note on an Economic Lot-sizing Problem with Perishable Inventory and Economies of Scale Costs:Approximation Solutions and Worst Case Analysis

This paper presents an economic lot-sizing problem with perishable inventory and general economies of scale cost functions. For the case with backlogging allowed, a mathematical model is formulated, and several properties of the optimal solutions are explored. With the help of these optimality properties, a polynomial time approximation algorithm is developed by a new method. The new method adopts a shift technique to obtain a feasible solution of subproblem and takes the optimal solution of the subproblem as an approximation solution of our problem. The worst case performance for the approximation algorithm is proven to be （4√2 ＋ 5）/7. Finally, an instance illustrates that the bound is tight.

（Dis）Economies of Scale in Business Software Systems Development and Enhancement Projects

In the software engineering literature, it is commonly believed that economies of scale do not occur in case of software Development and Enhancement Projects （D＆EP）. Their per-unit cost does not decrease but increase with the growth of such projects product size. Thus this is diseconomies of scale that occur in them. The significance of this phenomenon results from the fact that it is commonly considered to be one of the fundamental objective causes of their low effectiveness. This is of particular significance with regard to Business Software Systems （BSS） D＆EP characterized by exceptionally low effectiveness comparing to other software D＆EP. Thus the paper aims at answering the following two questions： （1） Do economies of scale really not occur in BSS D＆EP？ （2） If economies of scale may occur in BSS D＆EP, what factors are then promoting them？ These issues classify into economics problems of software engineering research and practice.

Scale and scope economies in small household rice farming in Vietnam

The Vietnamese agricultural sector has experienced a dramatic structural change based on increased specialization in rice cultivation.However,small-scale rice-farmers have continued to grow multiple crops,especially in less developed provinces.While the literature advocates crop diversification for reasons of both economic and ecological sustainability,there lacks empirical evidence as to whether crop diversification brings efficiency and productivity gains to small farms.The present study is the first applications of the input-oriented stochastic distance function approach in estimating scale and scope economies using data of multi-crop farming households in Vietnam.We find strong evidence of product-specific economies of scale.Scope economies are also present for rice,vegetable,and other annual crop production.This suggests that crop diversification enhances efficiency and productivity.However,there still exists significant technical inefficiency in crop production,indicating opportunities to expand farm output at the existing level of inputs and technologies.More specifically,our empirical results indicate that it is desirable to expand vegetable and other annual crop production in mountainous areas while rice cultivation can be further expanded in delta and coastal regions.

China＇s Agricultural Modernization and Economies of Scale： Barriers and Solutions

This paper identifies three stages in China's agricultural development with reference to macroeconomic development and international experience.While the first two stages focused on ensuring food security and raising farmer's income,the current stage must give priority to modernizing agricultural production.The lack of progress in this area is due to the following reasons:diminishing return to capital as a result of small and scattered farming operation which has compromised agricultural competitiveness;agriculture is overdependent on subsidy and protection under the conventional wisdom of the uniqueness of agriculture.This paper attempts to reveal the barriers to China s agricultural modernization and proposes recommendations on reforming the land and household registration systems to increase the economies of scale and productivity.

Data envelopment analysis for scale elasticity measurement in the stochastic case:with an application to Indian banking

In the nonparametric data envelopment analysis literature,scale elasticity is evaluated in two alternative ways:using either the technical efficiency model or the cost efficiency model.This evaluation becomes problematic in several situations,for example(a)when input proportions change in the long run,(b)when inputs are heterogeneous,and(c)when firms face ex-ante price uncertainty in making their production decisions.To address these situations,a scale elasticity evaluation was performed using a value-based cost efficiency model.However,this alternative value-based scale elasticity evaluation is sensitive to the uncertainty and variability underlying input and output data.Therefore,in this study,we introduce a stochastic cost-efficiency model based on chance-constrained programming to develop a value-based measure of the scale elasticity of firms facing data uncertainty.An illustrative empirical application to the Indian banking industry comprising 71 banks for eight years(1998–2005)was made to compare inferences about their efficiency and scale properties.The key findings are as follows:First,both the deterministic model and our proposed stochastic model yield distinctly different results concerning the efficiency and scale elasticity scores at various tolerance levels of chance constraints.However,both models yield the same results at a tolerance level of 0.5,implying that the deterministic model is a special case of the stochastic model in that it reveals the same efficiency and returns to scale characterizations of banks.Second,the stochastic model generates higher efficiency scores for inefficient banks than its deterministic counterpart.Third,public banks exhibit higher efficiency than private and foreign banks.Finally,public and old private banks mostly exhibit either decreasing or constant returns to scale,whereas foreign and new private banks experience either increasing or decreasing returns to scale.Although the application of our proposed stochastic model is illustrative,it can be potentially applied to all firms in the information and distribution-intensive industry with high fixed costs,which have ample potential for reaping scale and scope benefits.

数字经济、创业与中等收入群体规模

利用马克思资本循环理论、蒂蒙斯创业理论阐释数字经济扩大中等收入群体规模的理论逻辑,并利用2012—2021年中国31个省份的面板数据检验了数字经济对中等收入群体规模的影响。研究发现:数字经济能显著扩大中等收入群体规模。机制研究表明:数字经济能通过促进创业而扩大中等收入群体规模。具体而言,数字经济有助于促进创业融资和优化创业企业的要素配置,从而有助于扩大中等收入群体规模。进一步研究发现:良好的营商环境能强化数字经济对创业的促进作用,从而能强化数字经济对中等收入群体规模的扩大作用。异质性检验结果表明:组织型创业与自我雇佣型创业都能使数字经济更好地发挥其对中等收入群体规模的扩大作用;在数字经济的支持下,无论是在制造业中创业,还是在服务业中创业,均能显著扩大中等收入群体规模。

中国平台经济规模核算及预测

平台经济是数字经济的重要组成部分,测度平台经济的规模具有十分重要的现实意义。为此,本文结合国内外相关研究,将平台经济从数字经济的概念中剥离出来,对平台经济的生产与产出统计范围进行界定,构造平台经济规模核算框架,对2005—2021年平台经济增加值规模及其占GDP的比重进行统计测度,并通过指数平滑法和灰色预测模型对我国平台经济发展规模进行预测。本文研究结果为了解我国平台经济的发展现状及趋势、理解平台经济产业结构特征提供数据支撑,为把平台经济核算纳入现行国民经济核算体系提供参考建议。

我国畜牧业发展现状、存在问题及对策

畜牧业是我国农业农村经济的重要组成部分,对保障国家粮食安全和提高居民生活水平具有重要意义。近年来,我国畜牧业发展的内外部环境正在发生深刻的变化。本文分析了我国肉牛、生猪、肉鸡、肉羊产业的发展现状,发现我国畜牧业目前存在养殖场动物疫病风险加大,畜禽行业养殖环境约束趋紧,畜禽良种繁育能力不足,科技创新及人才支撑不足的问题。针对这些问题提出了构建完善的公共服务监管体系,科学提高疫情防控能力;推进规模化养殖和标准化生产;强化科技支撑,加快推进科技育种工作;提升技术研发能力,健全产业发展支撑体系等发展对策,以期为我国畜牧业健康发展提供理论参考。

数字经济发展对种植业碳排放效率的影响研究——基于中介和门槛效应的实证检验

农业源温室气体排放量(碳排放)仅次于工业,种植业作为农业的基础,其碳排放量在农业中占据较大比重,种植业碳减排对于“双碳”目标的实现具有重要意义。在“碳达峰、碳中和”的碳排放格局下,数字经济已成为推动种植业绿色低碳高质量发展的新引擎。本文在理论探讨基础上,结合2011—2021年中国31个省(自治区、直辖市,不包括中国香港地区、澳门地区和台湾地区)面板数据,综合利用固定效应回归模型、工具变量模型、中介效应模型、门槛效应模型,实证考察了数字经济发展与种植业碳排放效率之间的内在关系。研究发现,数字经济发展对种植业碳排放效率具有显著的正向影响,且存在农业生产功能与区域异质性;数字经济发展通过促进技术创新和规模经营来抑制种植业碳排放,且“技术创新效应”的贡献份额大于“规模经营效应”;数字经济发展对种植业碳排放效率的促进作用还受经济发展水平的影响,当经济发展水平低于阈值时,数字经济发展对种植业碳排放效率的影响并不显著,当经济发展水平超过阈值后,数字经济发展能够对种植业碳排放效率产生显著的提升效应。

规模经济与国有文艺院团效率增进——来自山西省的证据

规模经济是制造业和服务业供给主体必须追求的目标,艺术表演业也不例外。本文利用1989—2021年山西省国有院团的统计数据,构造长期平均成本产出函数,发现山西省国有文艺院团存在规模经济效应,但是成本产出组合偏离最优组合;国有经营院团生产效率优化空间较大,集体经营院团更能促进规模经济效应的形成。在做强做大文艺表演产业,提升国有文艺院团质量的同时,应降低院团运营中的管理冗余,充分发挥规模经济效应。

集聚外部性提升了农户全要素生产率吗?

技术进步和技术效率改善是促进粮食产业高质量发展,保障粮食安全的重要路径。随着水稻种植规模和稻农密度的增加,要素空间集中形成的集聚外部性不仅能够有效提升行业技术水平,而且还可以改善稻农技术非效率。基于湖南省2014-2020年间1248份水稻种植户微观数据,采用超越对数随机前沿生产函数模型,将表征集聚经济效应的种植规模和稻农密度,同时纳入前沿函数和技术非效率项中,综合考察集聚外部性对稻农全要素生产率的影响。研究结果发现:无论是水稻种植规模还是稻农密度,都显著地促进了水稻生产技术进步,提升了农户技术效率;两种集聚变量的产出弹性均为正,共同推动水稻产出前沿面外移;分地形和分农户种植面积的异质性回归结果与基准回归结果一致,结论具有稳健性。据此提出,水稻种植区要完善基础设施,利用土地政策满足农户需求,提升农业生产效率;利用土地整治等农田建设手段改善细碎化问题,推动村组生产专业化和规模化;通过改革土地制度、强化支持政策,结合地方实际优化农业结构,发挥水稻种植的规模和密度经济效应,提高全要素生产率。

流通数字化赋能全国统一大市场建设的机理与效应研究

建设全国统一大市场是加快构建新发展格局的基础支撑和内在要求。本文聚焦流通数字化发展对全国统一大市场建设的影响,实证检验流通数字化赋能全国统一大市场建设的传导机制和异质特征。研究发现,流通数字化发展能够显著促进全国统一大市场建设,且该研究结论具有较强的稳健性。机制检验结果表明,流通数字化发展能够通过加快创新要素流动、扩大企业规模、释放消费潜力等途径促进全国统一大市场建设。异质性检验结果表明,在基础设施水平、城镇化率和人口集聚程度较高地区,流通数字化对全国统一大市场建设的促进作用较为明显。进一步研究发现,流通数字化与统一大市场之间存在基于基础设施、城镇化率和人口集聚水平的门槛效应。本文研究结论为我国进一步加快流通产业的数字化转型、破除区域间要素流动壁垒、推进统一大市场建设提供了经验证据。

乡村区域共富的路径类型、动力机制与规划策略——基于浙江省3个典型案例的实证分析

新时代乡村振兴战略的根本目标是实现共同富裕。围绕单一村庄开展的建设提升已无法满足乡村发展的更高需求,从区域视角关注乡村共富成为当前的迫切要求。2003年启动的“千万工程”,不断推动浙江乡村建设由“单维”向“系统”转变,为乡村区域共富发展指明了方向,提供了注解。基于此,通过浙江省3个典型案例实证分析,深度剖析浙江省乡村区域共富的路径类型及其动力机制。研究发现,当前浙江省乡村区域共富路径主要包括乡村振兴联合体、特色村镇竞合体与产业文化和合体3种类型,其在形态特征、形成路径、动力结构等方面均存在差异。三者动力来源分别为社会价值认同、交易成本降低及规模经济驱动。在此基础上,提出应增强全局观念、创新公共产品供给、因地制宜提供专业化基础设施与公共服务设施等规划策略。这对于促进浙江省乡村区域共富发展具有现实意义,也为全国其他地区乡村发展提供借鉴与参考。

中国新型工业化道路:沿革、挑战与重塑

改革期间的中国工业化呈现出截然不同的两种阶段性特征:一是1979—1998年的“劳动密集型”;二是1998年至今的“资本深化型”。就工业化效率而言,前者来自于资源配置效率的改进,后者来自于动态规模效益。“资本深化型”工业化能否得以维系,从内生因素看,取决于“资本深化型”工业化所获得的动态规模效益是否足以阻止资本边际报酬的下降;从外部环境方面看,则有赖于本土工业能否提升自主创新能力,以摆脱对西方发达资本主义国家的技术依附、淘汰落后产能。从目前工业化的运行情况看,这两者都不乐观。要克服“资本深化型”工业化模式的局限性,发展新质生产力以开辟新型工业化道路,是当前的唯一选择。

数字经济对产业链韧性的影响研究

提升产业链韧性是适应世界形势变化、推进我国新型工业化、为实现中国式现代化构筑强大物质基础的必然举措。本文基于2011—2021年中国31个省份的面板数据,从抵抗能力、恢复能力、可持续发展能力和创新能力四个维度构建指标体系,运用熵权TOPSIS法测算出产业链韧性,然后使用固定效应模型与中介效应模型考察数字经济对产业链韧性的影响。结果表明:数字经济能够显著提升产业链韧性,但区域间存在差异,数字经济能够显著促进东部地区和西部地区产业链韧性提升,对中部地区影响不显著。机制分析发现,数字经济通过推动市场化进程和提升劳动力就业规模对产业链韧性产生促进作用。另外,在市场化水平高和劳动力就业规模大的条件下,数字经济提升产业链韧性边际效应递增。为更好地发挥数字经济对产业链韧性的促进作用,应加大各类科技研发投入力度,实现关键核心技术自主可控,增强产业基础能力,推进区域协调发展等。

乡村数字经济对农业灌溉用水效率的影响

文章基于2012-2021年省级面板数据,在测度乡村数字经济发展指数和结合灌溉水有效利用系数的基础上,构建Tobit模型分析乡村数字经济对农业灌溉用水效率的影响及其作用机制。

农地流转对农业数字经济发展的影响

基于2014—2021年全国省级面板数据,利用熵值法和固定效应模型,以农业机械化水平为调节变量,分析农地流转对农业数字经济发展的影响。结果表明:从整体上看,中国农业数字经济发展水平呈现良好的增长态势,但呈现出明显的“东高西低”的分布特征;农地流转能够显著促进农业数字经济发展,且存在显著的空间异质性,具体表现为东部地区农地流转促进了农业数字经济发展,中西部地区为负且不显著;农业机械化水平在农地流转对农业数字经济发展的影响中发挥着正向调节效应。

数字贸易对居民消费提质升级的影响研究

数字贸易是驱动消费规模增长和提质升级的重要抓手。选取省级面板数据研究数字贸易对居民消费提质升级的影响,研究结果显示:(1)整体上,数字贸易能够驱动居民消费提质升级,具体表现为品质消费规模扩大、消费质量提升和消费结构升级;(2)数字贸易对居民消费结构升级存在非线性影响,随着数字贸易发展水平的提升,数字贸易驱动消费结构升级的作用强度会经历先增强后减弱的倒U型变化趋势;(3)数字贸易能通过产业结构升级和消费需求增长驱动消费质量提升;(4)不同收入水平下数字贸易驱动消费结构升级存在门槛效应,数字贸易对低收入水平居民的驱动作用更强;(5)数字贸易对不同地区居民消费提质升级的影响方式与程度不一致,呈现出地区异质性。

Can whole steps of grain production be outsourced? Empirical analysis based on the three provinces of Jiangsu,Jilin,and Sichuan in China

Certain outsourcing services for agricultural management in China,such as pest control in grain production,have experienced prolonged sluggishness,contrasting with the relatively high level of outsourcing services observed in harvesting,land preparation,and sowing.This study examines the feasibility of implementing whole-step outsourcing in grain production by conducting a case study of rice and maize production in Jiangsu,Jilin,and Sichuan provinces in China.The provision of outsourcing services hinges on two essential conditions:technological advancements fostering specialized production and economies of scale,coupled with a market size sufficient to realize the aforementioned potential economies of scale.The results showed that outsourcing pest control or harvesting services had varying economies of scale.The outsourcing services in pest control were less common than in harvesting services,and their marginal growth space of the economies of scale with technological change was also smaller.Determined by the operational characteristics of pest control itself,the market scale of its professional services is small.Therefore,achieving the whole-step outsourcing of grain production necessitates not only technological innovation but also effective policy interventions to overcome the constraints of market scale.Such interventions include(1)optimizing crop layouts between planning regions and reducing land fragmentation and(2)supplying timely and effective inter-regional agricultural information for service providers aided by information technology.

虚拟集聚如何影响制造业企业高质量发展?

虚拟集聚对实现制造业企业高质量发展、助力建设制造强国具有重要意义。本文界定制造业企业虚拟集聚内涵、构建虚拟集聚模型,分析虚拟集聚对制造业企业高质量发展的影响效应及机制。从虚拟集聚载体和虚拟集聚网络两个维度构建制造业企业虚拟集聚关键词,借助软件Python爬虫技术从制造业企业上市公司年报中获取,并结合中国制造业企业上市公司微观数据进行实证检验。研究结果表明,虚拟集聚能够促进制造业企业高质量发展。机制分析结果表明,虚拟集聚能够通过知识溢出、规模经济和交易成本促进制造业企业高质量发展,但虚拟集聚不能加快企业合作创新。调节效应检验结果表明,企业外部的知识产权保护在虚拟集聚促进制造业企业高质量发展的过程中起正向调节作用,而这种正向影响不受企业技术密集度的影响。异质性分析结果表明,虚拟集聚对小型制造业企业、东部和中部制造业企业高质量发展的提升作用更强,而对不同成长周期企业的高质量发展的影响无明显差异。本文研究结论不仅有助于丰富制造业企业虚拟集聚及其影响企业高质量发展的理论研究,且在提高制造业企业虚拟集聚水平方面提供了政策启示。