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Article
Publication date: 1 April 1993

Choong Y. Lee

MRP is a priority‐planning technique, not an execution tool. Wastecan be avoided through the use of JIT as an execution tool, where onlythose materials which are actually…

Abstract

MRP is a priority‐planning technique, not an execution tool. Waste can be avoided through the use of JIT as an execution tool, where only those materials which are actually needed on the factory floor are “pulled”, when they are needed. Describes a hybrid manufacturing system which incorporates the traditional MRP system and the Japanese JIT system in a single framework. The rationale is not whether MRP or JIT is better; it is how they complement each other in a hybrid system. Specifically, this framework attempts to integrate both MRP and JIT production. The integrated hybrid system can provide better production planning, scheduling and control. It employs the logic of MRP and JIT, but it eliminates some of the inherent problems and drawbacks in both systems.

Details

International Journal of Operations & Production Management, vol. 13 no. 4
Type: Research Article
ISSN: 0144-3577

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Article
Publication date: 2 September 2019

Kateryna Pollack and Jan Clemens Bongaerts

Priorities of decarbonizing the mining sector together with an availability of cost-effective technological solutions lead renewable energy (RE) to become an attractive…

Abstract

Purpose

Priorities of decarbonizing the mining sector together with an availability of cost-effective technological solutions lead renewable energy (RE) to become an attractive energy source for the mining industry. Several pilot projects are run as hybrid systems, providing additional capacity to traditional energy systems. The purpose of this paper is to develop a mathematical model as a decision-making tool. The decision refers to a replacement of the fossil fuel system contains by the hybrid system in the sense of no return.

Design/methodology/approach

Four systems are considered. System one contains only a diesel plant. System two consists of a hybrid energy system with a photovoltaic (PV) part and a genset as back-up. System three includes a conventional natural gas combined cycle (CGCC) plant. Finally, system four covers a hybrid energy system with a PV part and CGCC turbine. The mathematical model is based upon the well-known concept of levelized cost of electricity.

Findings

The scenarios account for the degradation rate of PV modules, the PV yields of mines in different locations and the greenhouse gas emissions impact. The results show the break-even times of each scenario and the years of no return for the four systems in each scenario.

Research limitations/implications

The solution of the model is performed for two case-studies. Case study 1 compares the diesel and hybrid PV-diesel systems. Case study 2 compares the CGCC and hybrid PV-natural gas systems.

Practical implications

This model can be generalized to all mining settings, with specific practical implications for off-grid mines.

Social implications

The results of this paper bring a valuable contribution to carbon dioxide emissions reduction.

Originality/value

The paper aims to enhance the attention of decision-makers on fossil fuel and RE technologies increase the attractiveness of RE in powering mining operations.

Details

International Journal of Energy Sector Management, vol. 14 no. 1
Type: Research Article
ISSN: 1750-6220

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Article
Publication date: 24 October 2018

Omogbai Oleghe and Konstantinos Salonitis

This study aims to seek to advance a system dynamics-discrete event hybrid simulation modelling concept useful for taking improvement decisions where one needs to consider…

Abstract

Purpose

This study aims to seek to advance a system dynamics-discrete event hybrid simulation modelling concept useful for taking improvement decisions where one needs to consider the interactions between human factors and process flow elements in lean manufacturing systems.

Design/methodology/approach

A unique approach is taken to hybrid simulation modelling where the whole problem situation is first conceptualized using a causal loop diagram and stock and flow diagram, before transmitting to a hybrid simulation model. The concept is intended to simplify the simulation modelling process and make the concept pliable for use in various types of lean manufacturing problem situations.

Findings

The hybrid simulation modelling concept was applied to a lean manufacturing case where quality performance was sporadic mainly because of production pressures. The hybrid modelling concept revealed a solution that advanced full compliance with lean and one that required changes in job scheduling policies to promote both continuous improvement and throughput increases.

Research limitations/implications

Because non-tangible aspects of lean were objectively assessed using the hybrid modelling concept, the study is an advancement towards establishing a credible link between human resource aspects of lean and the performance of an organization.

Practical implications

The applied hybrid model enabled managers in the plant navigate the trade-off decision they often face when choosing to advance production output ahead of continuous improvement practices.

Originality/value

System dynamics-discrete event hybrid simulation modelling is a rarity in lean manufacturing systems.

Details

International Journal of Lean Six Sigma, vol. 10 no. 2
Type: Research Article
ISSN: 2040-4166

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Article
Publication date: 22 February 2008

Samuel Herb

Claimed to be programmable logic controllers (PLCs) that act like distributed control systems (DCSs), various people define hybrid systems differently: by functions, by…

Abstract

Purpose

Claimed to be programmable logic controllers (PLCs) that act like distributed control systems (DCSs), various people define hybrid systems differently: by functions, by industries served, by architecture, and even by no label at all. As a result, there is still confusion about the label “Hybrid Systems.” This paper aims to explore these issues briefly and to help understand and reduce confusion about these relatively recent hybrid systems, which are now also being called “Programmable Automation Controls” (PAC).

Design/methodology/approach

The paper compares DCSs, PLCs, centralized computer systems, use of industrial professional (personal) computers, original hybrid control systems, current hybrid control systems, evolution to PAC and shows evolution of new programming standards.

Findings

Hybrid control systems can readily become part of the overall plant productivity. This is a stepping‐stone towards complete enterprise control systems.

Research limitations/implications

No small part of this capability is the emerging standard for easy consistent configuration of hybrid systems, regardless of the vendor who supplies them.

Practical implications

Because of the emerging configuration standard, the hybrid system can be re‐configured as needed due to plant changes or market swing. This provides the user with “agile manufacturing.”

Originality/value

More than a “cheap DCS,” these hybrid control systems can be an inexpensive stepping‐stone towards managing the business as it was meant to be managed. What is important is that these elements can be introduced in manageable increments to meet tight budgets.

Details

Assembly Automation, vol. 28 no. 1
Type: Research Article
ISSN: 0144-5154

Keywords

Content available
Article
Publication date: 16 March 2021

Tomi Rajala and Petra Kokko

This study examines unexplored horizontal accountability types between public, private and third sector actors within a hybrid organization. The case organization was…

Abstract

Purpose

This study examines unexplored horizontal accountability types between public, private and third sector actors within a hybrid organization. The case organization was applying a novel alliance model to generate service paths for heterogeneous clientele consuming cultural, educational, health and social services. It was first to do so in Finland.

Design/methodology/approach

This research is on a case study that used documents and interviews to examine the design of the horizontal accountability. The descriptive analysis focused on identifying what type of formal accountability system was designed (i.e. who is the account holder, and who is accountable and for what and why).

Findings

An imbalanced accountability system was identified because accountability obligations were unevenly distributed between public, private and third sector actors. The private sector was the most accountable for performance, and the third sector (i.e. voluntary sector) was the least accountable. As account holders, the public, private and third sector actors were judging their conduct as account providers. This created a biased horizontal accountability system. The hybrid's accountability system was dynamic because the contracts made to establish the hybrid included opportunities to change horizontal accountability if future changes to the external environment affect too drastically the potential to achieve the hybrid's goals.

Originality/value

Three new concepts are proposed for studying dysfunctional accountability systems: dynamic, biased and horizontally imbalanced accountability.

Details

Accounting, Auditing & Accountability Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0951-3574

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Article
Publication date: 15 July 2019

Yong Li, Yanjun Huang and Xing Xu

Sensorless interior permanent magnet in-wheel motor (IPMIWM), as an exemplar of modular automation system, has attracted considerable interests in recent years. This paper…

Abstract

Purpose

Sensorless interior permanent magnet in-wheel motor (IPMIWM), as an exemplar of modular automation system, has attracted considerable interests in recent years. This paper aims to investigate a novel hybrid control approach for the sensorless IPMIWM from a cyber-physical systems (CPS) perspective.

Design/methodology/approach

The control approach is presented based on the hybrid dynamical theory. In the standstill-low (S-L) speed, the rotor position/speed signal is estimated by the method of the high frequency (HF) voltage signal injection. The least square support vector machine (LS-SVM) is used to acquire the rotor position/speed signal in medium-high (M-H) speed operation. Hybrid automata model of the IPMIWM is established due to its hybrid dynamic characteristics in wide speed range. A hybrid state observer (HSO), including a discrete state observer (DSO) and a continuous state observer (CSO), is designed for rotor position/speed estimation of the IPMIWM.

Findings

The hardware-in-the-loop testing based on dSPACE is carried out on the test bench. Experimental investigations demonstrate the hybrid control approach can not only identify the rotor position/speed signal with a certain load but also be able to reject the load disturbance. The reliability and the effectiveness of the proposed hybrid control approach were verified.

Originality/value

The proposed hybrid control approach for the sensorless IPMIWM promotes the deep combination and coordination of sensorless IPMIWM drive system. It also theoretically supports and extends the development of the hybrid control of the highly integrated modular automation system.

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Article
Publication date: 3 July 2017

Dênis Gustavo Leonardo, Bruno Sereno, Daniel Sant Anna da Silva, Mauro Sampaio, Alexandre Augusto Massote and Jairo Celso Simões

Shop floor control systems are generally major points of discussion in production planning and control literature. The purpose of this paper is to investigate how lean…

Abstract

Purpose

Shop floor control systems are generally major points of discussion in production planning and control literature. The purpose of this paper is to investigate how lean production control principles can be used in a make-to-order (MTO) job shop, where the volume is typically low and there is high variety. This paper examines the procedures involved in implementing a constant work-in-process (CONWIP)/Kanban hybrid system in the shop floor environment and also provides insights and guidelines on the implementation of a hybrid system in a high-variety/low-volume environment.

Design/methodology/approach

The authors review literature on Kanban, CONWIP, and CONWIP/Kanban hybrid systems to analyze how lean production control principles can be used in a MTO job shop. The second part focuses on the process of implementation. Using a case study of a manufacturer of electromechanical components for valve monitoring and controls, the paper describes how the operation is transformed by for more efficient shop floor control systems. Real experiments are used to compare pre- and post-improvement performance.

Findings

The study shows that the proposed hybrid Kanban-CONWIP system reduced the cycle time and achieved an increase of 38 percent in inventory turnover. The empirical results from this pilot study provide useful managerial insights for a benchmarking analysis of the actions to be taken into consideration by companies that have similar manufacturing systems.

Research limitations/implications

The statistic generalization of the results is impossible due to the use of a single case method of study.

Originality/value

This paper provides insights and guidelines on the implementation of a hybrid system in a high-variety/low-volume environment. The literature on real applications of hybrid CONWIP/Kanban by case study is limited.

Details

Journal of Manufacturing Technology Management, vol. 28 no. 6
Type: Research Article
ISSN: 1741-038X

Keywords

Content available
Article
Publication date: 4 March 2020

Marco Fioriti, Silvio Vaschetto, Sabrina Corpino and Giovanna Premoli

This paper aims to present the main results achieved in the frame of the TIVANO national-funded project which may anticipate, in a stepped approach, the evolution and the…

Abstract

Purpose

This paper aims to present the main results achieved in the frame of the TIVANO national-funded project which may anticipate, in a stepped approach, the evolution and the design of the enabling technologies needed for a hybrid/electric medium altitude long endurance (MALE) unmanned aerial vehicle (UAV) to perform persistent intelligence surveillance reconnaissance (ISR) military operations.

Design/methodology/approach

Different architectures of hybrid-propulsion system are analyzed pointing out their operating modes to select the more suitable architecture for the reference aircraft. The selected architecture is further analyzed together with its electric power plant branch focusing on electric system architecture and the selected electric machine. A final comparison between the hybrid and standard propulsion is given at aircraft level.

Findings

The use of hybrid propulsion may lead to a reduction of the total aircraft mass and an increase in safety level. However, this result comes together with a reduced performance in climb phase.

Practical implications

This study can be used as a reference for similar studies and it provides a detailed description of propulsion operating modes, power management, electric system and machine architecture.

Originality/value

This study presents a novel application of hybrid propulsion focusing on a three tons class MALE UAV for ISR missions. It provides new operating modes of the propulsion system and a detailed electric architecture of its powertrain branch and machine. Some considerations on noise emissions and infra-red traceability of this propulsion, at aircraft level.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 5
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 28 September 2018

Osama Abdulhameed, Abdurahman Mushabab Al-Ahmari, Wadea Ameen and Syed Hammad Mian

Hybrid manufacturing technologies combining individual processes can be recognized as one of the most cogent developments in recent times. As a result of integrating…

Abstract

Purpose

Hybrid manufacturing technologies combining individual processes can be recognized as one of the most cogent developments in recent times. As a result of integrating additive, subtractive and inspection processes within a single system, the relative benefits of each process can be exploited. This collaboration uses the strength of the individual processes, while decreasing the shortcomings and broadening the application areas. Notwithstanding its numerous advantages, the implementation of hybrid technology is typically affected by the limited process planning methods. The process planning methods proficient at effectively using manufacturing sources for hybridization are notably restrictive. Hence, this paper aims to propose a computer-aided process planning system for hybrid additive, subtractive and inspection processes. A dynamic process plan has been developed, wherein an online process control with intelligent and autonomous characteristics, as well as the feedback from the inspection, is utilized.

Design/methodology/approach

In this research, a computer-aided process planning system for hybrid additive, subtractive and inspection process has been proposed. A framework based on the integration of three phases has been designed and implemented. The first phase has been developed for the generation of alternative plans or different scenarios depending on machining parameters, the amount of material to be added and removed in additive and subtractive manufacturing, etc. The primary objective in this phase has been to conduct set-up planning, process selection, process sequencing, selection of machine parameters, etc. The second phase is aimed at the identification of the optimum scenario or plan.

Findings

To accomplish this goal, economic models for additive and subtractive manufacturing were used. The objective of the third phase was to generate a dynamic process plan depending on the inspection feedback. For this purpose, a multi-agent system has been used. The multi-agent system has been used to achieve intelligence and autonomy of different phases.

Practical implications

A case study has been developed to test and validate the proposed algorithm and establish the performance of the proposed system.

Originality/value

The major contribution of this work is the novel dynamic computer-aided process planning system for the hybrid process. This hybrid process is not limited by the shortcomings of the constituent processes in terms of tool accessibility and support volume. It has been established that the hybrid process together with an appropriate computer-aided process plan provides an effective solution to accurately fabricate a variety of complex parts.

Details

Rapid Prototyping Journal, vol. 24 no. 6
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 9 October 2020

Lisa Baudot, Jesse Dillard and Nadra Pencle

Building on the research program of Dillard and Brown (2015) and Dillard and Vinnari (2019), specifically related to an “ethic of accountability,” this paper recognizes…

Abstract

Purpose

Building on the research program of Dillard and Brown (2015) and Dillard and Vinnari (2019), specifically related to an “ethic of accountability,” this paper recognizes accountability systems as key to how organizations conceptualize their responsibility to society. The objective is to explore how managers of hybrid organizations conceptualize responsibility and the role of accountability systems in their conceptualization.

Design/methodology/approach

This paper studies hybrid organizations that are for-profit entities with explicitly recognized non-economic imperatives. Semi-structured interviews are conducted with managers of organizations that pursue certification as a B-Corporation, often in conjunction with a legal designation as a benefit corporation.

Findings

Managers of the hybrid organizations evidenced a broader responsibility logic that extends beyond responsibility to shareholders. This pluralistic orientation and broader set of objectives are expressed in a set of certification standards that represent an accountability system that both enables and constrains the way responsibility is understood. The accountability system reflects a “felt” accountability to the “other” manifested, for example, as generational accountability, with the other (re)created relative to the certification standards.

Research limitations/implications

Certifications and standards represent accounting-based accountability systems that produce a type of accountability in which the certification becomes the overall objective nudging out efforts to take accountability-based accounting seriously (Dillard and Vinnari, 2019). At the same time, the hybrids under study, while not perfect exemplars, incline toward an ethic of accountability (Dillard and Brown, 2014) that moves them closer to accountability-based accounting.

Originality/value

The findings reveal perspectives of managers embedded in hybrid organizations, illustrating their experiences of responsibility and accountability systems in practice (Grossi et al., 2019). The insights can be extended to other hybrid contexts where accountability systems may be used to demonstrate multiple performance objectives. We also recognize the irony in the need for an organization to be required to attain a special license to operate in a more responsible manner.

Details

Accounting, Auditing & Accountability Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0951-3574

Keywords

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