Yohanes Kristianto

Adaptive fuzzy vendor managed inventory control for mitigating the Bullwhip effect in supply chains

This paper proposes an adaptive fuzzy control application to support a vendor managed inventory (VMI). The methodology applies fuzzy control to generate an adaptive smoothing constant in the forecast method, production and delivery plan to eliminate, for example, the rationing and gaming or the Houlihan effect and the order batching effect or the Burbidge effects and finally the Bullwhip effect. The results show that the adaptive fuzzy VMI control surpasses fuzzy VMI control and traditional VMI in terms of mitigating the Bullwhip effect and lower delivery overshoots and backorders. This paper also guides management in allocating inventory by coordinating suppliers and buyers to ensure minimum inventory levels across a supply chain. Adaptive fuzzy VMI control is the main contribution of this paper.

A model of resilient supply chain network design: A two-stage programming with fuzzy shortest path

A supply chain network design needs to consider the future probability of reconfiguration due to some problems of disaster or price changes. The objective of this article is to design a reconfigurable supply chain network by optimizing inventory allocation and transportation routing. A two-stage programming is composed according to Benders decomposition by allocating inventory in advance and anticipating the changes of transportation routings; thus the transportation routing is stochastic in nature. In addition, the fuzzy shortest path is developed to solve the problem complexity in terms of the multi-criteria of lead time and capacity with an efficient computational method. The results and analysis indicate that the proposed two-stage programming with fuzzy shortest path surpasses the performance of shortest path problem with time windows and capacity constraint (SPPTWCC) in terms of less computational time and CPU memory consumption. Finally, management decision-making is discussed among other concluding remarks.

Adopting TQM approach to achieve customer satisfaction

Purpose – The purpose of this paper is to present the results of a survey of customer satisfaction with regard to the strategy of total quality management (TQM) adopted in a wheat flour milling company.Design/methodology/approach – A survey was conducted to learn more about customer expectations and satisfaction. The respondents were all customers of a flour‐based food processor. Quality function deployment (QFD) was applied to improve customer service performance by focusing on customer satisfaction, value and retention.Findings – The results show that customer satisfaction has increased steadily over a period of three years. The QFD approach helped to design a competitive product by aligning the company resources to customers’ needs.Research limitations/implications – The findings are limited to a specific food manufacturing company and for this reason they cannot be generalized to the whole in service sector. Further research is needed for other service companies.Practical implications – The findings m...

Mass customization design of engineer-to-order products using Benders' decomposition and bi-level stochastic programming

Leveraging product differentiation and mass production efficiency in mass customization basically entails a configure-to-order paradigm. In the engineer-to-order (ETO) business, however, companies build unique products in response to ‘foreseeable’ customer specifications. The key challenge of ETO mass customization lies in the complexity of accommodating future design changes when customers are involved in customizing design specifications. This paper proposes a two-stage, bi-level stochastic programming framework to tackle ETO mass customization. At the first stage, product platform configuration is integrated with production reconfiguration, which is formulated as a shortest path problem with resource constraints (SPPRC) to optimize production delays within the capabilities of the process platform. Benders’ decomposition algorithm is applied to solve this optimal configuration problem owing to its high computational efficiency. The second stage scrutinizes the optimal configuration resulting from the first stage for scaling optimization of design parameters (DPs) for each module. All DPs are differentiated by standard or customizable DPs. A bi-level stochastic program is implemented to leverage conflicting goals between the producer (leader) and consumer (follower) surpluses. As a result, ETO customization design is anchored with optimal values of standard DPs and optimal value ranges of customizable DPs. A case study of ship engine and power generator ETO design is presented, demonstrating the feasibility and potential of the ETO mass customization framework.

A system level product configurator for engineer-to-order supply chains

System level configuration is a common need for engineering businesses.Engineer to order processes and incomplete configurations present challenges.A prototype system for system level configuration management is presented. Supply chains in construction, infrastructure building, ship building, factory design and conveyor systems are operating in an engineer-to-order type of environment. Companies in these project-based businesses have special requirements for product configuration. Products have configuration dependencies with each other and there are system level configuration dependencies between several products. Incomplete product configuration items that are subject to change or require engineering work prior to production can occur. This paper introduces the requirements for system level configuration and proposes a prototype solution for ship projects and engine-room related supply chains.

Comparison of vertical-flow constructed wetlands with and without supplementary aeration treating decentralized domestic wastewater

Constructed wetlands (CWs) are efficient in reducing excessive contamination from wastewaters. However, oxygen inside CW beds is frequently low especially when substrate clogging problems appear after long-term operation, and this may become a limited factor for the treatment of wastewaters. Aimed at dealing with the issue of a low oxygen content in CW systems, two laboratory-scale vertical-flow constructed wetlands (VFCWs) with and without an aeration device (called VFCW-a and VFCW-c, respectively) were designed in this study to test the contribution of supplementary aeration to the treatment of decentralized domestic wastewater. Results showed that under the intermittent operation of about 45 days, two VFCW units were successfully started up by using activated sludge as seed sludge. Compared to VFCW-c, VFCW-a had a better resistance ability to organic shock loads and its removal function could be effectively recovered within a short period after the introduction of organic shock loads. Under intermittent operation with a 12 h idling time, the ideal hydraulic retention time (HRT) of VFCW-a was 42 h, about 6 h shorter than that of VFCW-c. Likewise, under intermittent operation with 42 h HRT, the ideal idling time of VFCW-a was 12 h, still about 6 h shorter than that of VFCW-c. Under intermittent operation with HRT-42 h and an idling time of 12 h, SS, COD, TN and TP removal efficiencies in VFCW-a could reach 81.2%, 85%, 89.9% and 77.9%, respectively. The VFCW unit with supplementary aeration is an efficient innovation for the treatment of decentralized domestic wastewater.

Knowledge sharing in supply chain

This chapter introduces the thermodynamics analogy as a means of studying knowledge sharing in supply chain. The study finds that distance and the knowledge capacity of the supplier are important to reduce knowledge sharing uncertainty. Furthermore, higher contact frequency between the supplier and the buyer without considering supplier capacity is proven to be insignificant to reduce knowledge sharing uncertainty. For intellectuals, the mechanism provides a new approach to explicate knowledge sharing in supply networks. Besides, it provides deep-rooted opening point for supplementary empirical assessment. The mechanism facilitates managers to expand their understanding of composite circumstances embedded into global supply networks to share their knowledge. With that enhanced understanding, the managers can spotlight their actions, which help further to perk up their firms’ competitiveness provoked by the knowledge sharing activities.

Logical reconfiguration of reconfigurable manufacturing systems with stream of variations modelling: a stochastic two-stage programming and shortest path model

This article studies logical reconfiguration of reconfigurable manufacturing systems (RMS) to minimise production lead times and buffer inventory level when the process variations and worker utilisation are considered. Since the RMS must be flexible for different job orders, the design of RMS requires diagnostic methodology and stream of variations (SoV) theory for rapid ramp-up in order to control the process variations that might occur as time goes on. The flexibility of the manufacturing systems is represented by logical elements of RMS in terms of changeable production batch size. The three phases solution is proposed by (1) utilising SoV modelling to find the allowable production lead times, (2) finding the optimum buffer stock level and production capacity at changeable production batch size and (3) finding worker routings at optimum worker utilisation. Monte carlo simulation is employed at Phase 1 to get the optimum production lead times, Phase 2 decision is formulated as a stochastic two-stages programming where buffer inventory level (first stage decison) has to be established prior to changeable production batching at future period and shortest path problems (SPP) algorithm is used to find an optimum worker routing at Phase 3. A serial inventory production (SIP) is used as an example to answer the following research questions: (1) What is the impact of SoV on both buffer inventory allocation and worker routings? (2) When is logical reconfiguration most beneficial in improving SIP profitability? (3) What is the impact of logical reconfiguration on both cost and lead time reduction? Three instances are used to investigate the effect of logical reconfiguration on the different structure of SIP systems. The results and analysis indicate that consideration of SoV is capable of increasing the profit, reducing operation lead times and maximising worker utilisation. Finally, management decision-making is discussed among other concluding remarks.

A study of technology adoption in manufacturing firms

Purpose – The purpose of this paper is to study the effect of technology adoption on operational competitiveness by taking an example from international manufacturing companies.Design/methodology/approach – This paper develops a conceptual model to generate strategic flexibility and benefit for a manufacturing firm by managing manufacturing strategy and technology adoption with different leadership roles.Findings – The results show that the leadership role is a significant factor to motivate strategic flexibility and generate higher benefit. For intellectuals, the mechanism provides a new approach to explicate technology adoption in a manufacturing company. Besides, it provides a deep‐rooted preliminary point for supplementary empirical assessment. The mechanism facilitates managers to expand their understanding of the leadership role for trust building and knowledge sharing in manufacturing firms.Practical implications – With that enhanced understanding, the managers can spotlight their actions, which he...

Steel supply chain management by simulation modelling

Purpose – The aim of this paper is to propose a simulation study of the “steel supply chain” to demonstrate the effect of inventory management and demand variety on the bullwhip effect mitigation.Design/methodology/approach – The relevant literature is reviewed, and then the simulation model proposed.Findings – This study identifies reasons for sharing information under varying levels of demand and some variants, and demonstrates the benefits of mitigating the bullwhip effect by applying a design of experiment. It is shown that the information sharing is able to mitigate the bullwhip effect in the steel supply chain by extending the order interval and minimising the order batch size.Research limitations/implications – This study explores the factors associated with the bullwhip effect. This research is focused on built‐to‐order simulation, so the results are only oriented on the basis of orders; hence a simultaneous order‐ and forecast‐based steel supply chain should be carried out in the future.Practical...