基于两次平衡计算的南昌市耕作层土壤剥离再利用空间配置研究

研究目的:探讨耕作层土壤剥离再利用空间配置思路与方法,并以南昌市为例进行实证研究,为相关工作提供借鉴。研究方法:提出基于线性规划及OD成本矩阵方法的两次平衡计算的耕作层土壤剥离再利用土方空间配置思路。首先,确定剥离、覆土优先度并结合供求关系划定供需圈,在供需圈内部进行第一次调配平衡;其次,对于内部不能平衡的供需圈,进行第二次跨圈调配平衡,达到缩短运输距离,控制成本目的。研究结果:(1)南昌市耕作层剥离量能够满足覆土数量与质量的需求;(2)空间配置结果共划定18个供需圈,供需圈内土方调配加权平均运输距离为6 682 m,小于期望值10 km,满足项目实施要求;(3)共有15个供需圈存在土方量不平衡问题,跨圈调配的距离平均为72 071 m,满足短距离运输的要求。研究结论:以耕作层土壤剥离、覆土优先度及供求关系为基础划定供需圈,基于线性规划及OD成本矩阵的两次平衡计算的空间配置思路与方法,可以优化运输距离,减少运输成本,提高项目实施效益。本文提出的空间配置思路可以为耕作层剥离再利用工程的顺利实施提供理论与方法借鉴。     

Design of Digital Agricultural Extension Tools: Perspectives from Extension Agents in Nigeria

Given the marked heterogeneous conditions in smallholder agriculture in Sub-Saharan Africa, there is a growing policy interest in site-specific extension advice and the use of digital extension tools to provide site-specific information. Empirical ex-ante studies on the design of digital extension tools and their use are rare. Using data from a choice experiment in Nigeria, we elicit and analyze the preferences of extension agents for major design features of ICT-enabled decision support tools (DSTs) aimed at site-specific nutrient management extension advice. We estimate different models, including mixed logit, latent class and attribute non-attendance models. We find that extension agents are generally willing to use such DSTs and prefer a DST with a more user-friendly interface that requires less time to generate results. We also find that preferences are heterogeneous: some extension agents care more about the effectiveness-related features of DSTs, such as information accuracy and level of detail, while others prioritise practical features, such as tool platform, language and interface ease-of-use. Recognising and accommodating such preference differences may facilitate the adoption of DSTs by extension agents and thus enhance the scope for such tools to impact the agricultural production decisions of farmers.     

Pareto-improving social optimal pricing schemes based on bottleneck permits for managing congestion at a merging section

Akamatsu, Sato, and Nguyen (2006 Akamatsu, T., Sato, S., &; Nguyen, X. L. (2006). Tradable time-of-day bottleneck permits for morning commuters (in Japanese). JSCE Journal of Infrastructure Planning 62(4), 605–620.[Crossref] , [Google Scholar]) proposed a first-best pricing scheme based on the concept of bottleneck permits. The scheme allows permit holders to pass a bottleneck at specified times and is shown to be able to minimize social cost. However, the scheme is not always Pareto-improving in that it may harm some drivers. The objective of this study is to design Pareto-improving pricing scheme with bottleneck permits for a V-shaped two-to-one merge bottleneck. First, the paper formulates the morning commute model in the network and describes the arrival time choice equilibrium in the network with merging bottleneck. Secondly, we show that the first-best pricing scheme with bottleneck permits for this V-shaped network does not always achieve a Pareto improvement, with the cost of one group of drivers is increased by the permit pricing, a phenomena akin to the bottleneck paradox of Arnott, de Palma, and Lindsey (1993 Arnott, R., de Palma, A., &; Lindsey, R. (1993). Properties of dynamic traffic equilibrium involving bottlenecks, including a paradox and metering. Transportation Science 27(2), 148–160.[Crossref], [Web of Science ®] , [Google Scholar]). We propose three implementations of bottleneck permits for Pareto-improving: (1) merging priority rule is included in the bottleneck permits scheme by creating different market for each origin; (2) the permit revenues are refunded as monetary compensation to drivers whose cost is increased; and (3) the permit revenues are used to expand bottleneck capacity. For each implementation, we derive their equilibrium solutions and demonstrate that the Pareto improvement is achieved and social cost is decreased by using the permit revenues for expanding the bottleneck capacity.     

Success factors for continuous supply chain process improvement: evidence from Japanese manufacturers

This study explores how firms can realise ‘continuous’ supply chain process improvement. Specifically, this study proposes the success factors of routinised activities (also called ‘repeated activities’) in the supply chain process improvement. Eight Japanese manufacturers are selected for the case studies. These firms are selected based on their supply chain process operation capabilities. From the case studies, we find that the planning of supply chain process improvement depends on the existing stage of the firm’s Supply Chain Management reform. In addition, even firms with high scores for supply chain process operation capabilities do not have supply chain performance systems. Furthermore, quite surprisingly, many Japanese manufacturers tend to improve their supply chain processes in the absence of such systems.     

提高采煤机截齿可靠性和寿命的途径

从截齿的制造质量、材料、几何形状和参数等方面,分析截齿的可靠性和寿命的关键影响因素。     

大学新生英语语音现状及其改进措施分析

本文作者根据长期以来在高校英语专业教学中教授英语语音的经验体会,对当前大学新生英语语音学习现状进行分析并提出了改进措施等方面的建议。     

巴中市农田土壤重金属分布及生态风险评价

[目的]通过测定秦巴山区巴中市农田土壤中镉(Cd)、铅(Pb)、锌(Zn)3种重金属元素的含量及分布特征,为农田重金属防治科学决策的制定提供数据支撑。[方法]文章采用内梅罗指数和潜在生态风险指数来综合评价巴中市土壤重金属污染状况。[结果]巴中市农田土壤锌平均含量比四川省丘陵地区背景值高6.78%,而镉和铅含量均未超出其背景值,总体评价良好,但各检测点之间差异较大,镉含量最多超出背景值5.7倍。内梅罗指数评价结果显示,全市平均综合污染指数为1.10,接近清洁状态。潜在生态风险指数评价结果显示,其最小值为15.94,最大值为177.74,平均值为35.38。[结论]巴中市农田土壤重金属污染状况基本处于低度风险级别,但各地块污染程度不尽一致,应因地制宜,采取适当措施治理土壤污染。     

高职铸造专业实训改进研究与实施

为了提高高职学院铸造专业学生实训效果,通过消失模铸造改进传统木模手工造型,既提高了学生实际动手能力,又使学生掌握了该门先进铸造技术,增强了学生就业竞争能力。     

常熟市道路交叉口设计方案

城市道路交叉路口是保证城市通行能力的要塞。本文通过重置行车道,调整绿信比、设置导流岛等方式试图缓解部分路段目前交叉路口的交通压力。     

浅谈如何确保企业质量体系有效运行

企业在取得ISO9000质量体系认证后,应正确对待所取得的证书,并采取有效措施,确保质量体系能够持续有效的运行。结合工作实际情况,对维持质量体系有效运行的几种措施进行了详细的阐述。