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.

Unveiling the impact and mechanism of digital technology on agricultural economic resilience

Enhancing the economic resilience of agriculture is essential for promoting sustainable and high-quality agricultural development.The emergence of digital technology has created new opportunities in this field.However,existing research predominantly focuses on traditional agricultural factors and technologies.Therefore,the impact of digital technology on agricultural economic resilience within the broader context of the“production-operation-industry”system in agriculture has not been comprehensively explored.To bridge this gap,this study analyzes panel data from 30 Chinese provinces from 2011 to 2020.It employs the static Van Dorn’s law and a dynamic spatial panel model to examine how digital technology empowers agricultural resilience.The findings indicate a continuous strengthening of digital technology development in China,albeit with significant polarization and spatial imbalances.Moreover,the resilience of the agricultural economy undergoes notable fluctuations,initially narrowing and subsequently displaying an upward trend.Digital technology clearly plays a pivotal role in empowering resilience through agricultural scale operation,industrial transformation,and technological progress.Its impact,particularly on the promotion of resilience in the eastern region and non-grain-producing areas and on high-level agricultural economies,also shows regional and technological variations.

Assessment of Stress Cognitive Control and Executive Function with Stress Control Rating Scale (ECOSTRESS) and Low Resolution Brain Electromagnetic Tomography (LORETA) (In Portuguese People in Situations of Unemployment and Economic Insufficiency)

This article reviews the constructs of stress, appraisal, coping, according to a transactional perspective, and executive function, and presents a stress control rating scale (ECOSTRESS), which design is founded in these constructs. This psychometric tool is useful in the assessment of cognitive control of stress, correlated with the function of dorsolateral prefrontal cortex. It has been validated for its use in the assessment of Portuguese people in situations of stress related to unemployment and economic insufficiency. Also, within the context of the cognitive control of stress, it is highlighted the usefulness of low resolution brain electromagnetic tomography (LORETA).

The Ban on Illegal Mining in Ghana: Environmental and Socio-Economic Effect on Local Communities

The study was conducted to assess the effects of small-scale (artisanal) gold mining and its social and economic implications on the people in Amansie West District of Ghana. The artisanal gold mining communities were studied using secondary data from scholarly articles and journals, books, conference papers, research reports, policy documents, working papers, and briefs. Descriptive and systematic analyses were conducted. The result indicated that youth aged between 21 - 30 were most likely to engage in illegal mining operations in the selected study areas. The study revealed that farmland had been destroyed, making farming difficult for the inhabitants. It is evident from the review that dug-out pits from mining serve as breeding grounds for mosquitoes and death traps for humans. The study, therefore, accentuates the need for illegal small-scale gold mining to be formalised and strategic interventions and policies proposed for the protection of Ghana’s Natural resources. Furthermore, community members should be involved in policy-making and environmental protection issues to help control the menace of landscape destruction. Although the ban on illegal gold mining activity by the government has caused more people to lose their jobs leading to livelihood challenges in mining communities, it is a step in the right direction, as the ban seeks to halt and check the illegal small-scale mining sector. The study recommended alternative livelihood and income-generating projects such as beekeeping, mushroom culture, grasscutter rearing, and agroforestry technologies including the growth of economic fruit trees as alternative livelihood ventures.

A Probe into Economic Regionalization Theory Analysis Framework of Conflicts Between Scale Expansion and Transaction costs

The economic regionalization practice led by China local governments has gradually evolved into chaos. Local governments compete to declare for higher-leveled and large-scaled economic regions to obtain more economic resources and policy support in the way of policy game. The author argues that the regionalization chaos is attributed to the reason that the present theoretical support for economic regionalization overemphasizes the economic growth brought about by the economic regionalization but ignores the effect of transaction cost, which leads to constraint loss on the economic regionalization theory analysis framework. Then, the introduction of economic regionalization analysis framework based on the conflicts between scale expansion and transaction costs would establish equilibrium conditions to set up a moderate scale development for economic regions. The author hopes that the acceptance of this framework into the economic regionalization decision-making system would give guidance for making more appropriate regionalization decisions.

Date Envelopment Analysis of Steelmakers＇ Economical Scale in China

In view of the fact that Chinese steelmakers are not in a developed competitive market, the economical scale of Chinese iron and steel enterprises is measured by Date Envelopment Analysis （DEA） in batches compared with international one. The deep reasons are revealed why Chinese large steelmakers are in batches not in economical scale.

Role of Accessibility and Socio-Economic Variables in Modelling Population Change at Varying Scale

During past decades, effects of accessibility to growth have been considered extensively. In previous studies, however, matter of scale has been largely ignored. In this study, relevance of travel accessibility and essential socio-economic variables for explaining population change analysed with a multi-scalar study setting by the case of Finland. The analytical framework of the study relies on applied geographical information systems (GIS). Relationships between population change and explanatory variables were established with non-linear multiple regression, generalised additive models (GAMs). The data consist of population and socio-economic grid cell databases based on authentic records, transport network models, including complete digital road network database. Models were established at six resolutions between 2 km × 2 km and 24 km × 24 km. The main result is that the performance of the models, explaining and predicting population change, strongly relies on potential accessibility particularly at accurate resolutions. An important finding is also that it is possible to establish explain and predict population change tolerably at accurate resolutions and well at coarse resolutions, as the performance of models increases with scale.

Influential Factors on Economic Benefit of Rice Farmers

[Objective] This study was to provide references for the improvement of agricultural economic benefit by analyzing the main factors on influencing the economic benefit of rice farmer. [Method] Field survey was carried out on 300 rice farmers in Suizhou, Wuxue and Xiaogan of Hubei Province. Through the descriptive statistics to the production input and output data of the sample farmers, the econometric model was established to conduct empirical test on the economic benefit of rice farmer and the influential factors. The optimal production scale for rice farmer was also estimated, and through the theoretical and empirical analysis of the optimal production scale, countermeasures were put forward with the aim to promote economic benefit of rice farmer. [Result] The application of fertilizer affected the economic benefit most, followed by the planting area; food policy, farming population and average economic income per capita had significant effects on the economic benefit of rice production; economic benefit was beneficial for cost control. [Conclusion] This study had great practical and instructive significance for stabilizing national food production, ensuring regional and national food safety.

Access to Credit by SMEs and Implications for Economic Growth in Nigeria

The purpose of this study is to examine the impact of credit availability to SMEs on the economic growth in Nigeria. The study period was from 1981 to 2012. Vector autoregressive model was employed to avoid the problem of endogenity. The results show that though inflation has a negative effect on SMEs fmancing, it still significantly influences economic growth. This paper therefore concludes that there is a need for government to intensify efforts to increase SMEs financing in the country through the introduction of a special intervention fund for SMEs.

Strategies to Promote Sustainable Development of Industrial Parks in Vietnam＇s Northern Key Economic Zone

Industrial Parks （IPs） in the Northern Key Economic Zone of Vietnam （NKEZ） have been making significant contributions to the development of the zone since the first two industrial parks--Noi Bai in Hanoi and Nomura in Hal Phong--were established 15 years ago. So far, there have been 51 IPs in the zone, covering a total area of 13,000 ha. Such IPs play a crucial role in mobilizing capital from domestic and international investors for investments in infrastructure enhancement, trade and production aimed at promoting the economic structure transition. However, besides the above benefits, there are a number of unstable factors preventing further development of the IPs. Thus, the objectives of this study are two-fold. The first is to analyze the unstable factors, and the second is to map out strategies to enhance sustainable development of industrial parks in Vietnam＇s northern key economic zone.

Socio-Economic Characteristics of Three Artisanal Fisheries Communities in the Northern Sudanese Red Sea Coast

Socio-economic characteristics related to fishing gears and boats from three selected small-scale fishers’ communities (Oseif, Dungonab and Mohammed Qol) in the northern part of the Sudanese Red Sea coast were studied. The study was designed to provide base line data and information on the current socio-economic situation, factors that determine the use of fishing gear, types of boats and fishing equipment, challenges facing fishers and the extent to which fishing gear and boats are related with the socio-economic characteristics of the fishers community in the study sites. Fieldwork was carried out during 2016. The study methods included a series of interviews based on questionnaires, field observations and focus group discussions. The results of the study showed that the most common fishing gears are handlines, cast nets and gillnets. The two types of boats used at the study sites are motorized fiberglass and houri (motorized and paddled) with a V-shaped hull. Boat ownership varies among fishers. Each fisher can have several types of gears in different numbers. Target fish species, season, efficiency of gear and fishing location were the main factors determining the use of fishing gear at study sites, respectively. All fishers are men and most have families of at least four people. The majority of fishers are between 21 and 50 years old and work mainly in fishing. They inherited fishing knowledge within the family, and most of them have been working in artisanal fishing for more than 10 years. Fishers have relatively good net incomes compared to other government employers in the study sites. Most fishers work full time in fishing. A small number of fishers work part-time with the possibility of undertaking other income-generating activities such as animal husbandry and seasonal agriculture. The main challenges identified by fishers at the study sites were fish prices, sea surface roughness and high cost of fishing materials, respectively. Most fishers perceived a recent decline in both catch size and abundance.

开发区升格政策能促进企业创新增量提质吗?

通过构建多时点DID模型实证检验开发区升格政策对企业创新数量和创新质量的影响,结果表明:省级开发区升格通过降低制度性交易成本、提升市场化程度和加速创新要素流入对企业创新产出数量和产出质量产生促进作用,该政策对非民营企业、非高技术制造行业、高新区和小规模城市的作用效果更强。因此,要充分发挥开发区“以升促建”的创新激励效应,不仅要注重有为政府和有效市场的结合,还要根据城市固有经济特征优化开发区制度环境。

Economic optimization on two time scales for a hybrid energy system based on virtual storage

This paper proposes an economic optimization method with two time scales for a hybrid energy system based on the virtual storage characteristic of a thermostatically controlled load(TCL). The optimization process includes two time scales in order to ensure accuracy and efficiency. Based on the forecast load and energy supply of the system, the first time scale is day-ahead economic operating optimization, carried out to determine the minimum operating cost for the whole day, and to find the period of greatest cost to which the second time scale optimization is applied. Using the virtual storage characteristic, the second time scale is short-term detailed optimization carried out for these particular hours. By dispatching thermal load in this period and adjusting energy supply accordingly, we can find the optimal economic performance, and customer requests are taken into account to ensure satisfaction. A case study in Tianjin, China illustrates the effectiveness of this method and proves that a TCL can make a great contribution to improving the economic performance of a hybrid energy system.

Market Scale, Home Market Effect and Evolution of Spatial Economic Structure: China's Regional Coordinated Development on Different Spatial Scales

By using a new economic geography model of multi-region to study the impact of market scale on spatial economic structure,we find that the home market effect plays a key role in it.At different development periods,under external shocks such as transportation costs and so on,industry shares will change due to the distribution of market scale.The spatial economic structure will gradually evolve into such forms as single core or dual-core structure,especially"central collapse"will be found in the process.Such results can be used to analyze the practical problems,including the"central collapse"in the east,central and west regions of China,the structure of city clusters,etc.With the rapid development of transportation infrastructures,China will form a variety of development patterns on different spatial scales owing to home market effect.The regional convergence can be reached through reducing the economic distance and promoting agglomerative economies,which will help achieve regional coordinated development.

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.

农业社会化服务与小农户的组织化:不同服务模式的比较

本研究通过对比政府主导型、市场主导型和村集体经济组织主导型社会化服务模式,讨论了小农户如何被组织起来以及组织成本由谁承担的问题。在由政府主导的社会化服务模式中,小农户因受到政府补贴的吸引而达成了临时的合作,但这种组织化具有暂时性。在市场主导型社会化服务模式中,小农户或被整合到规模经营主体的种植模式中,或被服务组织重塑。在这两种服务模式中,小农户都是被动的参与者,其组织化程度并未提高。村集体经济组织可能通过重建与小农户的双向权责均衡关系,通过收取服务费用的方式来解决组织成本问题。这种双向的权责均衡关系使村集体经济组织与小农户之间建立起有机的利益联结,从而使该组织对小农户的组织和动员成为可能。

高等教育规模、城镇化与区域经济增长机制研究——基于省级面板数据的证据

高等教育规模是经济持续增长的重要因素,城镇化是否在高等教育规模对区域经济增长的影响中发挥了重要中介效应,需要进一步研究。为此,可以基于2004一2020年国家统计局省级面板数据,分析高等教育规模与区域经济增长的关系,辨析城镇化在两者关系中的作用,进而探究高等教育规模、城镇化对区域经济增长的影响机理。研究结果表明:高等教育规模促进区域经济增长具有直接作用;城镇化对区域经济增长具有正向驱动作用;城镇化在高等教育规模促进区域经济增长过程中发挥了中介效应。这也证明了“高等教育规模一城镇化一区域经济增长”机制的存在。为有效利用该机制,建议适度扩大高等教育规模,加快培养高层次创新人才,因地制宜加快新型城镇化建设,推动城镇产业结构升级,建设现代化产业体系,促进区域经济快速健康发展。

1949—2021年我国成灾地震及其损失的时空特征

为了解地震致灾规律,有效制定防灾减灾规划,进一步减轻地震灾害损失,收集整理了1949—2021年我国及周边地区震级不小于5.0级的成灾地震及其灾害损失数据,从时间、空间两方面研究了他们的分布特征,研究结果表明:453次成灾地震共造成死亡约35万人,受伤约76万人,直接经济损失约11249亿元(折算值),其中重大地震灾害造成的灾害损失占比巨大。随着时间推移,年份上存在明显的地震多发年和少发年,年代上成灾地震次数有所增加,地震造成的经济损失加速增长,死亡人数、受伤人数有不同程度的减少。从地域上看,胡焕庸线西侧成灾地震发生频次高但平均损失小;经济分区中,西部地区成灾地震发生频次最高而平均损失最小,东部地区成灾地震次数次之但平均损失最高,中部和东北部地区成灾地震次数最少,灾害损失中等;云南省和四川省成灾地震次数最多,地震灾害损失最严重。同时期地震强度相近的成灾地震,发生在经济发达、人口密度高的区域的人员伤亡和经济损失更为严重。2000年以后小震大灾事件频次增加,多发生在胡焕庸线东侧及经济分区中的东部、中部地区,小震造成的大灾现象由原来的人员伤亡多转向经济损失大。

冷能梯级利用的港口多能微网双层不确定性经济调度

为有效挖掘港口液化天然气(LNG)冷能利用的低碳灵活性潜力,充分发挥多时间尺度协同优化效应,提出一种考虑LNG冷能梯级利用的港口多能微网(MEMG)鲁棒-随机双层不确定性经济调度模型。首先,考虑LNG深冷-中冷-浅冷等各个温区的低碳灵活性潜力,建立低温碳捕集-冷能发电-直接冷却的冷能梯级利用模型,并以此为基础形成捕集-存储-利用协同的碳处理流程。其次,根据等概率逆变换生成考虑预测误差时序相关性的风电场景,并基于Wasserstein距离的0-1规划模型进行场景削减。再次,针对风电预测误差随时间尺度增加而增大的特性,构建多时间尺度优化的鲁棒-随机双层不确定性经济调度模型,上层通过分布鲁棒优化保证日前预调度决策鲁棒性,下层通过随机优化保证日内滚动调度决策经济性。最后,仿真结果表明,所提考虑冷能梯级利用的鲁棒-随机双层调度模型在解决日前长时间尺度预测精度低与日内短时间尺度易陷入局部最优矛盾的同时,可赋予港口MEMG更多经济性、低碳性及供电灵活性。

规模化CCUS-EOR项目技术经济性分析及启示

社会各界对规模化全流程CCUS-EOR项目经济性及其他相关重要问题认识不足,不利于跨行业、跨地区、跨部门项目实施。中国CCUS/CCS项目累积注入二氧化碳量超过1000万t,积累了丰富项目运营经验;基于我国驱油类CCUS产业链技术现状和成熟度分析,认为在鄂尔多斯盆地有序开展规模化全流程CCUS项目技术可行,结合区域油藏地质特点,提出边学习经验、边工程建设、边运行项目、边认识规律、边调整方案的复杂油藏CCUS滚动建设模式;选择陕西榆林—安塞—定边地区煤化工碳源与代表性油藏,开展了基于管道输送的300万吨级CCUS项目方案设计和投资概算;用改进的全流程CCUS项目经济评价模型,分析基准收益率、财税金融政策、碳交易价格、产量不确定性等可控变量对项目经济性的影响,对比若干规模化CCUS项目的临界效益井口碳价,提出统一产业链各环节经济评价基准收益率有助于三跨型CCUS项目合作,实施绿色低息贷款可降低CCUS-EOR项目临界效益油价,采取“后CCUS项目交易、埋存量下限交易、埋存减量绿色补偿”可解决CCUS项目碳交易争议,严格CO_(2)驱油试验选区可进一步改善项目经济性,以上核心产业政策建议有助于推进鄂尔多斯盆地CCUS技术规模化应用。