A rolling horizon simulation approach for managing demand with lead time variability

This paper proposes a rolling horizon (RH) approach to deal with management problems under dynamic demand in planning horizons with variable lead times using system dynamics (SD) simulation. Thus, the nature of dynamic RH solutions entails no inconveniences to contemplate planning horizons with unpredictable demands. This is mainly because information is periodically updated and replanning is done in time. Therefore, inventory and logistic costs may be lower. For the first time, an RH is applied for demand management with variable lead times along with SD simulation models, which allowed the use of lot-sizing techniques to be evaluated (Wagner-Whitin and Silver-Meal). The basic scenario is based on a real-world example from an automotive single-level SC composed of a first-tier supplier and a car assembler that contemplates uncertain demands while planning the RH and 216 subscenarios by modifying constant and variable lead times, holding costs and order costs, combined with lot-sizing techniques. Twenty-eight more replications comprising 504 new subscenarios with variable lead times are generated to represent a relative variation coefficient of the initial demand. We conclude that our RH simulation approach, along with lot-sizing techniques, can generate more sustainable planning results in total costs, fill rates and bullwhip effect terms.     

供应链管理中的供应链计划

论述了供应链的战略计划、战术计划和运作计划。基于信息技术的供应链管理系统中的利用多组织、货源规则和分销清单构造供应链的物流网络,可以进行供应链的多组织的整体计划或分步计划,并进一步研究了供应链计划的逻辑、方法。通过举例说明了供应链计划的整体计划和分步计划运行方法。最后讨论了应用高级计划及排程的供应链计划和ERP的差异。     

Order timing strategies in a single-supplier,multi-retailer system

The timing of retailer order placement is an important factor in supply chain performance in systems with uncertain end-customer demands. Retailers often prefer short order lead times, which permits the resolution of demand uncertainty prior to order placement, and reduces the risks associated with excess inventory. Suppliers, in contrast, prefer long lead times, in order to match supply output with retailer demand. These conflicting preferences create tension between a supplier and retailers regarding order timing preferences. This paper considers order timing preferences within a strategic framework involving a supplier and one of its retailers in a multiple-retailer system. We identify and explore several mechanisms a supplier can use within this framework to induce early retailer order placement and improve expected cost performance.     

The impact of dual-market on supply chain configuration for new products

Given a firm’s supply chain network, the key objective of supply chain configuration (SCC) is to determine a subset of supply chain partners to be involved in development, sourcing, production, distribution and support of a new product at the highest level of efficiency and expected responsiveness. Current literature on SCC realises the importance of considering the demand dynamics associated with the new product diffusion (NPD). However, these studies assume one-segment market for new products, a single homogenous consumer segment. Recent research in marketing indicates that such simplification might be fatal because a diverse and significant number of product categories may experience a dual-market structure, namely early and main markets, and generate a different demand dynamics. The objectives of this study are to: (i) develop a hybrid optimisation model, capturing both SCC decisions and the demand dynamics of dual-market NPD process; (ii) based on real-world data for a host of electronic product categories, various SCC networks and NPD demand dynamics, examine the new integrated optimisation model under one- and two-segment market; and (iii) present relevant managerial implications and guidelines for supply chain and marketing managers. Our extensive comparative computational experiment with 26 categories of consumer electronic products show that on average the relative net profit may improve significantly, when the market is considered as two-segment.     

网络化敏捷供应链销售管理研究与系统开发

将网络化和敏捷供应链管理的思想应用到企业销售管理中,提出了通过节点企业间及时准确地进行信息交流以快速响应市场需求的网络化敏捷供应链销售管理模式,在此基础上开发了基于B／S结构的敏捷供应链销售管理系统,提高了实施企业销售管理的协调能力和应变能力。     

Rolling horizon,multi-product production planning with chance constraints and forecast evolution for wafer fabs

In this paper, we study production planning models for semiconductor wafer fabrication facilities (wafer fabs) that consider both safety stocks at the finished goods inventory level and workload-dependent lead times. The evolution of demand forecasts over time follows the multiplicative Martingale Model of Forecast Evolution (MMFE) for multiple products and is incorporated into the planning models via shortfall-based chance constraints, permitting the simultaneous determination of production quantities and safety stocks. We study two variants of this formulation, one that considers forecast updates and one that does not. A planning model with workload-dependent lead times that does not consider safety stocks is used for comparison. The performance of the planning models is assessed in a rolling horizon environment using a simulation model of a scaled-down wafer fab. We find that the chance-constrained model with forecast updates outperforms the one without forecast updates with respect to expected service level and profit. Both chance-constrained models outperform the model without safety stocks. These results indicate that considering forecast evolution in production planning models can lead to improved performance by exploiting the advance demand information provided by the forecast updates.     

An empirical study of impacts of production mix,product route efficiencies on operations performance and profitability: a reverse logistics approach

This research studies the impact of two reverse logistics business strategies on profitability of the firm through operations management (OM). The study is employed on scrap steel industry. The first strategy is production mix efficiency (PME), which is involved in the process of producing goods. The second strategy is product route efficiency (PRE), which engages in the transportation of goods. Our finding indicates that OM alone does not have a positive impact on profitability. However, the two strategies have a positive effect on profitability, which provides a potential answer to firms trying to improve profitability.     

Production planning in automotive powertrain plants: a case study

Based on a real case study from the automotive industry, this paper deals with production planning in powertrain plants. We present an overview of the production planning process and propose a mixed integer linear programme to determine the production quantities of each product over a planning horizon of several days. Then, using real data of an engine assembly line, we simulate the performance obtained through the proposed model within a rolling horizon planning process. We perform multiple tests in order to evaluate the impact of two parameters involved in this process: planning frequency and frozen horizon length. Furthermore, in order to illustrate the value of improving coordination between engine plants and their customers, we evaluate the impact of the quality of demand information (orders and forecasts). We analyse the simulation results and provide insights and recommendations in order to achieve a good trade-off between service level, inventory, and planning stability.     

Managing configurable products in the computer industry: Planning and coordination issues

With the increase in the drive towards greater customer satisfaction, there has been a proliferation in the variety of products offered by manufacturers. Variety provides considerable choice to customers and encourages manufacturers to modularize their product lines. However, associated with a broad product line are complexities related to design, forecasting, coordination and operations. In this paper, we discuss some of these important issues.     

Green supply chain contracts with eco-labels issued by the sales platform: profitability and environmental implications

Considering environmentally conscious consumers, a manufacturer, and a sales platform which provides eco-labels for qualified manufacturers, this paper develops a supply chain model to study how eco-labels affect green supply chain operations, from the profitability and environmental perspectives. The results show that the sales platform prefers the agency contract, but the manufacturer prefers the wholesale price contract. Considering the performance of the supply chain, the agency contract brings a higher profit while the wholesale price contract results in a bigger environmental improvement. An unexpected but interesting result is that when the agency contract is used and consumer green awareness increases, the sale price declines rather than increasing as it does under the wholesale price contract. This decline happens because the required marketing effort of the sales platform will be lower, which incentivises the platform to reduce the commission rate. Consequently, the manufacturer faces a lower commission rate and a higher margin when consumers display greater green awareness. Moreover, as the core and more powerful player of the supply chain, the sales platform can propose a platform-led revenue sharing contract to fully coordinate the supply chain, which improves the performance of the supply chain both in profitability and environmental perspectives.     

Integration of promotion and production decisions in sales and operations planning

This paper presents a new modelling framework for developing a sales and operations plan that integrates promotion and production planning decisions. We adopt a rich demand function that captures the dynamics and heterogeneity of consumer response to price promotions by simulating purchase incidence, consumer choice and quantity decisions, as well as household’s inventory level. Our numerical study reveals interesting findings on the benefits of developing an integrated sales and operations plan as well as the optimal timing and number of promotions, and more importantly, how these findings are influenced by the mutual dependence of marketing- and production-related factors.     

A survey of semiconductor supply chain models Part II: demand planning,inventory management,and capacity planning

Part I of this three-part series described semiconductor supply chains from the decision-making and functional perspectives, using this as a framework to review the industrial engineering and operations research literature on the problems arising in these supply chains. Part I then reviewed the literature on Strategic Network Design, supply chain coordination, sustainability and simulation-based decision support. This paper, Part II, reviews the areas of Demand Planning, Inventory Management and Capacity Planning in semiconductor supply chains. Part III concludes the series by discussing models to support Master Planning, Production Planning and Demand Fulfilment in this industry.     

考虑销售努力和运输时间的农产品供应链弹性契约

目的 进一步实现农产品供应链数量弹性契约利润最大化。方法 在市场需求随机的条件下,考虑销售努力和运输时间为影响需求的关键变量,建立起由供应商和零售商组成的农产品供应链数量弹性契约模型。基于该模型引入奖励与惩罚策略,以实现农产品供应链弹性契约的一致性和有效性。结果 结合农产品特征,通过具体的模型优化方法和算例分析得出最优值以及各变量与最优销售努力水平、最优运输时间、最优订货量和整体农产品供应链利润之间的相关关系。结论 农产品供应链弹性契约能实现协调下的利润最大化,对农业经营主体企业开展农产品供应链弹性研究具有重要的理论和实践价值。     

Value chain management for commodities: a case study from the chemical industry

We present a planning model for chemical commodities related to an industry case. Commodities are standard chemicals characterized by sales and supply volatility in volume and value. Increasing and volatile prices of crude oil-dependent raw materials require coordination of sales and supply decisions by volume and value throughout the value chain to ensure profitability. Contract and spot demand differentiation with volatile and uncertain spot prices, spot sales quantity flexibility, spot sales price–quantity functions and variable raw material consumption rates in production are problem specifics to be considered. Existing chemical industry planning models are limited to production and distribution decisions to minimize costs or makespan. Demand-oriented models focus on uncertainty in demand quantities not in prices. We develop an integrated model to optimize profit by coordinating sales quantity, price and supply decisions throughout the value chain. A two-phase optimization approach supports robust planning ensuring minimum profitability even in case of worst-case spot sales price scenarios. Model evaluations with industry case data demonstrate the impact of elasticities, variable raw material consumption rates and price uncertainties on planned profit and volumes.