Modelling the effects of population aggregation on the efficiency of insect pest control

Summary A methodology is developed to assess the effects of spatial distribution on the efficiency of insect pest control. This methodology is especially applicable to pest control methods whose efficiency of action depends either positively or negatively on pest density It is applied here to the sterile insect technique and pheromone trapping for male annihilation, which both depend negatively on density. This methodology relies on quantifying clumps of various size and then relating this to efficiency of control and predicting the total pest production given the information on clump sizes and efficiency of control for each clump size. It is found that control is about four times as difficult for a population that is highly clumped (k of the negative binomial distribution=0.25) as for a regularly dispersed population.     

Assessing the Accuracy of Self-Reported Data: an Evaluation of the Toxics Release Inventory

Self-reported regulatory data are hard to verify. This article compares air emissions reported by plants in the Toxics Release Inventory with chemical concentration levels measured by EPA pollution monitors. We find that the large drops in air emissions reported by firms in the TRI are not always matched by similar reductions in measured concentrations from EPA monitors. When the first digits of the monitored chemical concentrations follow a monotonically decreasing distribution, we expect (via Benford's Law) a similar distribution of first digits for the TRI data. For lead and nitric acid the self-reported data do not follow the expected first digit pattern. This suggests that for these two heavily regulated chemicals plants are not reporting accurate estimates of their air emissions. JEL Classification K32, Q53     

Lean Control for Make‐to‐Order Companies: Integrating Customer Enquiry Management and Order Release

A lead time that is short, predictable, and reliable is an increasingly important criterion in supplier selection. Although many companies may achieve this through lean implementation, high‐variety manufacturers, for example, small and medium‐sized make‐to‐order companies, have found that lean's planning and control techniques do not apply. This article outlines a planning and control concept known as workload control (WLC) that integrates customer enquiry management, including a due‐date setting rule, with order release control. Simulation is then used to assess its impact on shop performance. Results demonstrate that an integrated WLC concept can reduce the percentage of tardy jobs—so short lead times can be realistically quoted—while also reducing and stabilizing workloads. WLC can level demand and production over time when work is not standardized and it is not possible to synchronize flows on the shop floor. Results are shown to be robust to changes in routing characteristics, the mix of orders with due dates specified by the customer and proposed internally, and the strike rate (or order‐winning probability). Hence, an integrated approach to WLC represents an important step toward achieving lean in make‐to‐order companies.     

中国股市限售股解禁的减持效应研究

限售股解禁及其减持现象将在中国股市长期存在,利用博弈分析和实证研究以深刻认识该现象并阐述其影响机制和影响程度,进而为相关治理途径选择提供依据.通过序贯博弈模型和同时决策的静态博弈模型分析限售股解禁的减持效应,并基于事件研究法进行实证研究.博弈模型推导表明.减持效应可能存在;当已流通股与解禁股的相对规模差异不大时存在减持效应的自稳定机制.实证分析证实了前述推断.并发现减持效应出现自稳定机制时往往伴随着股价的显著下跌;解禁日后存在一段观望期,期间减持效应不显著,但之后出现大规模的减持行为;提前反应明显强于减持效应,限售股解禁的心理冲击影响可能大于实际减持压力.要缓解限售股的解禁和减持压力,关键在于大幅度提升市场时股票的需求,有效承接供给规模的巨量增加,而其重点是提升市场投资需求和持股信心.     

普惠金融数字化、消费环境优化与农村居民消费动力释放

扩大内需、培育完整的内需体系亟需释放农村居民消费动力,普惠金融数字化是否有效释放了农村居民消费动力？消费环境优化又在其中起到什么作用？文章在系统梳理普惠金融数字化、消费环境优化与农村居民消费动力释放的关系原理基础上,利用我国2011—2021年的省际面板数据,从消费环境优化的视角出发,实证检验了普惠金融数字化对农村居民消费动力的释放作用、传导机制以及门槛效应。研究发现:普惠金融数字化对农村居民消费具有显著的正向影响,意味着普惠金融数字化促进了农村居民消费,有利于释放农村居民消费动力;普惠金融数字化可以通过促进消费环境优化进而释放农村居民消费动力,即消费环境优化是普惠金融数字化释放农村居民消费动力的传导机制;普惠金融数字化对农村居民消费动力的释放作用存在基于消费环境的门槛效应,即在消费环境的不同门槛区间范围,普惠金融数字化对农村居民消费动力的释放作用差异较为明显,随着消费环境的进一步优化,普惠金融数字化对农村居民消费动力的释放作用也会不断增强;普惠金融数字化对农村居民的生存型消费与发展享受型消费均产生了促进作用,有利于农村居民消费动力的全面释放,但相对于生存型消费,普惠金融数字化更有利于释放农村居民发展享受型消费动力,从而推动农村居民消费结构升级。文章研究结论所蕴含的政策含义包括:深耕普惠金融数字化,促进其与农村产业发展的深度融合,加强网络消费贷款与互联网金融等数字化金融产品创新,统筹区域间普惠金融数字化的协调发展,助力农村居民消费动力释放;全力推进消费环境优化,将消费环境治理聚焦于农村流通领域,构建通畅高效的农村流通设施体系,建设系统的农村消费者权益保护平台,营造安全良好的农村消费环境,充分激发农村居民消费潜能;制定差异化的居民收入提升策略,科学规划小城市与城镇协调发展,统筹解决"一老一小"人口结构问题,系统发挥农村居民收入、城镇化发展、人口年龄结构等因素的居民消费协同效应。     

Setting the control limit at release for stability assurance

A common task in quality control is to determine a control limit for a product at the time of release that incorporates its risk of degradation over time. Such a limit for a given quality measurement will be based on empirical stability data, the intended shelf life of the product and the stability specification. The task is particularly important when the registered specifications for release and stability are equal. We discuss two relevant formulations and their implementations in both a frequentist and Bayesian framework. The first ensures that the risk of a batch failing the specification is comparable at release and at the end of shelf life. The second is to screen out batches at release time that are at high risk of failing the stability specification at the end of their shelf life. Although the second formulation seems more natural from a quality assurance perspective, it usually renders a control limit that is too stringent. In this paper we provide theoretical insight in this phenomenon, and introduce a heat-map visualisation that may help practitioners to assess the feasibility of implementing a limit under the second formulation. We also suggest a solution when infeasible. In addition, the current industrial benchmark is reviewed and contrasted to the two formulations. Computational algorithms for both formulations are laid out in detail, and illustrated on a dataset.     

The Effect of Liability and Patch Release on Software Security: The Monopoly Case

An abundance of flawed software has been identified as the main cause of the poor security of computer networks because major viruses and worms exploit the vulnerabilities of such software. As an incentive mechanism for software security quality improvement, software liability has been intensely discussed among both academics and practitioners for a long time. An alternative approach to managing software security is patch release, which has been widely adopted in practice. In this paper, we examine these two different ways of mitigating customer risk in the software market: liability and patch release. We study the impact of both mechanisms on a monopolistic software vendor's decision on security quality. We find the conditions under which each mechanism is effective in terms of improving security quality and increasing social surplus. The heterogeneous nature of loss is identified to be a key factor for the effectiveness of the liability mechanism. On the other hand, patch release can be effective and welfare‐enhancing regardless of the nature of loss as long as customers incur low patching cost, and/or the vendor incurs low patch development cost. We also examine the impact of customer misperception of the outcome from vulnerable software on the effectiveness of liability.     

基于独立售电公司双角色的Stackelberg博弈模型分析

在新一轮电力市场化改革初期，电力市场输配售还处于未完全分开的状态。独立售电公司作为一种双角色主体首先要与电力批发商针对批发价进行博弈，然后与寄生公司进行市场博弈，形成了两阶段的Stackelberg博弈。本文采用逆推法，先用以价格为博弈策略的Bertrand博弈和以零售电量为博弈策略的Cournot博弈对第二阶段的最优目标进行求解，再通过Rubinstein博弈对第一阶段的均衡批发价进行求解。结果表明：在线性需求曲线假定下，独立售电公司如果采用单一的价格博弈手段参与市场，会陷入无限循环的价格调整，最终被迫退出市场；而若采用零售电量为博弈策略，则即使在改革初期寄生公司具有绝对价格优势时，电力市场化依然可以降低均衡电价，提高市场竞争性。     

突发疫情环境下考虑订单释放时间的零售物流配送路径优化研究

“新冠肺炎”疫情突发严重危及了人们的生活安全，而物流保障在疫情防控、保民生活、稳定社会方面却起到了重要支撑作用。以保证民生的零售物流配送为背景，本文研究考虑订单释放时间的车辆路径优化问题，以配送完工时间与运输成本的加权之和最小为目标，构建了线性规划模型,并设计了改进的迭代局部搜索求解算法。该算法采用基于多种邻域结构和改进的US算法的局部搜索过程以增强算法的寻优能力，通过引入大路径和最优分割过程获得高质量的初始解和打破机制以增强算法的搜索效率。同时，提出一些性质用于拉格朗日松弛算法，为本文研究问题提供高质量的下界。最后，数值实验部分通过求解标杆算例和文中算例验证了模型和算法的有效性，并对订单释放时间和模型参数进行灵敏度分析，结果表明本文模型和算法能够为零售物流配送的效率提升和成本控制提供有效的决策支持。