The Value Stream Hierarchical Model: A Practical Tool to Apply the Lean Thinking Concepts at All the Firms’ Levels

The increasing competition in the global markets is pushing many manufacturers to start the lean transformation with the final goal of being a Lean Enterprise, which applies the Lean thinking concepts at all its levels, from production to management. The biggest problem in this transition is to have a tool that consistently measures the undergoing evolution in the value stream selected, regardless of its extent, in order to take the subsequent actions needed. The main objective of this paper is to provide such a tool, the Value Stream Hierarchical Model (VSH Model), which could fit with every kind of manufacturing enterprise taking into account also the recent shift to industry 4.0 and the related new technologies available. In addition, another purpose of the model is to provide a scalable point of view that allows to “zoom in” on the company entity, based on the desired level of detail and the related information required. The VSH Model has born as a mix of the architectures existent in literature (ARIS, CIMOSA, PERA), which describe the enterprise from different point of views and levels, and the Lean Thinking concepts, starting from the Lean production tools and variables, passing through the Lean Accounting variables and ending with the Lean Management KPIs. The VSH model has already been applied to practical cases, consisting of a group of companies, as part of the industrial research carried out in Italy by the Politecnico di Torino

Ordered Arrays of SiGe Islands from Low-Energy PECVD

SiGe islands have been proposed for applications in the fields of microelectronics, optoelectronics and thermoelectrics. Although most of the works in literature are based on MBE, one of the possible advantages of low-energy plasma-enhanced chemical vapor deposition (LEPECVD) is a wider range of deposition rates, which in turn results in the possibility of growing islands with a high Ge concentration. We will show that LEPECVD can be effectively used for the controlled growth of ordered arrays of SiGe islands. In order to control the nucleation of the islands, patterned Si (001) substrates were obtained by e-beam lithography (EBL) and dry etching. We realized periodic circular pits with diameters ranging from 80 to 300 nm and depths from 65 to 75 nm. Subsequently, thin films (0.8–3.2 nm) of pure Ge were deposited by LEPECVD, resulting in regular and uniform arrays of Ge-rich islands. LEPECVD allowed the use of a wide range of growth rates (0.01–0.1 nm s−1) and substrates temperatures (600–750°C), so that the Ge content of the islands could be varied. Island morphology was characterized by AFM, while μ-Raman was used to analyze the Ge content inside the islands and the composition differences between islands on patterned and unpatterned areas of the substrate

Enhanced Logic Performance with Semiconducting Bilayer Graphene Channels

Realization of logic circuits in graphene with an energy gap (EG) remains one of the main challenges for graphene electronics. We found that large transport EGs (>100 meV) can be fulfilled in dual-gated bilayer graphene underneath a simple alumina passivation top gate stack, which directly contacts the graphene channels without an inserted buffer layer. With the presence of EGs, the electrical properties of the graphene transistors are significantly enhanced, as manifested by enhanced on/off current ratio, subthreshold slope and current saturation. For the first time, complementary-like semiconducting logic graphene inverters are demonstrated that show a large improvement over their metallic counterparts. This result may open the way for logic applications of gap-engineered graphene.Comment: Accepted by ACS Nan

Industry 4.0: A Bibliometric Analysis in the Perspective of Operations Management

This study aims to analyse the literature regarding the characteristics of Industry 4.0 in the context of operations management. The analysis covers the evolution of publications over time, the countries involved, the most prolific journals, the most cited authors, and the identification of the most frequent words that can generate insights for the research agenda. A total of 235 articles published between 2011 and 2017 were collected through an automated process from the Scopus and Web of Science databases and later analysed using data mining, bibliometric indicators analysis, clusters analysis, networks analysis, and word cloud. The bibliographic analysis explained the interaction between the various concepts and techniques associated with the central theme. These concepts and respective characteristics discussed allow an understanding and the development of agenda with theoretical possibilities to fill current research gaps

Towards digital lean manufacturing: A Brazilian case

Purpose - The purpose of this paper is to present a case study to describe the contact points between industry 4.0 technologies and lean manufacturing practices, that characterize the concept of digital lean manufacturing. Design/methodology/approach - After building a research framework extracted from the literature review, a single and in-depth case study was carried out in a Brazilian factory to understand the implementation of the digital lean manufacturing. The data were analyzed using descriptive statistics and content analysis, and resulted in the development of a conceptual map. Findings - The results revealed characteristics regarding six contact points implemented in the organization investigated. Also, it was observed that the results with the digitization of lean practices are consistent with the traditional literature, as they are aimed at reducing operating costs, eliminating waste, increasing quality, reducing lead time and real-time information. Research limitations/implications - The results of the research are based on a single case study and cannot be generalized. Therefore, the application of the same research framework will be conducted in other companies. Practical implications - Understanding the requirements for implementing the contact points illustrated in this case can help lean practitioners in the process of converting to the digital lean manufacturing model. However, it is understood that the implementation of DLM requires investments in technology and organizational culture aligned to the digital transformation. Originality/value - This work represents the first attempt to verify the adequacy of a research framework for the characterization of digital lean manufacturing practices

Lean Six Sigma in manufacturing process: a bibliometric study and research agenda

Purpose: The purpose of this paper is to develop a bibliometric study about Lean Six Sigma (LSS) in the manufacturing process and to conduct an analysis of sources of publication, authorship, citations and other bibliometric indicators. This paper also identifies the research agenda for future research related to the LSS approach in manufacturing processes. Design/methodology/approach: A total of 508 articles published during the period 2002 to 2017 were collected through an automated process from the Scopus and Web of Science databases and later analyzed using techniques such as data mining, bibliometric indicators analysis, cluster analysis, network analysis and word cloud. The boundaries of the study cover studies directed to the manufacturing processes. Findings: The research identified 1,110 authors from 54 countries and 15 most prolific journals among the 162 journals investigated. The study unveils relevant articles, authors and journals that have discussed LSS initiatives in the manufacturing process. Practical implications: The study findings can make practitioners aware of the state of the art and the specificities of the most prolific studies. Furthermore, this paper also intends to clarify the project themes and tools most used in these works. Originality/value: The geographical locations of influential articles and authors are revealed. Additionally, frequently used words are listed and helped to develop a research agenda that highlights relevant themes, methods and industries

Quality And Safety Management Systems: Joint Action For Certification Of Small Firms In An Industrial Cluster In Brazil

This paper presents and discusses a proposal for joint action among small firms in an industrial cluster in Brazil for the certification of quality and safety management systems. It proposes a management system model, the implementation process, and periodic auditing. It is the result of an action-research project developed in a metal-mechanical cluster. Its originality lies mainly in the proposal for a joint action programme for the certification of companies, led by the cluster governance agency, to increase the collective efficiency of a cluster. Despite the obstacles encountered, this proposal can help to reduce the difficulties faced by small businesses in implementing and maintaining management systems, and in the long run to foster a culture of quality and safety management. It also contributes to joint actions within the cluster. The challenge faced by the cluster governance agency is to sustain the certification programme in the long term

Charge transport mechanisms in inkjet-printed thin-film transistors based on two-dimensional materials

Printed electronics using inks based on graphene and other two-dimensional materials can be used to create large-scale, flexible and wearable devices. However, the complexity of ink formulations and the polycrystalline nature of the resulting thin films have made it difficult to examine charge transport in such devices. Here we report the charge transport mechanisms of surfactant- and solvent-free inkjet-printed thin-film devices based on few-layer graphene (semimetal), molybdenum disulfide (MoS2, semiconductor) and titanium carbide MXene (Ti3C2, metal) by investigating the temperature, gate and magnetic-field dependencies of their electrical conductivity. We find that charge transport in printed few-layer MXene and MoS2 devices is dominated by the intrinsic transport mechanism of the constituent flakes: MXene exhibits a weakly localized 2D metallic behaviour at any temperature, whereas MoS2 behaves as an insulator with a crossover from 3D Mott variable-range hopping to nearest-neighbour hopping around 200 K. Charge transport in printed few-layer graphene devices is dominated by the transport mechanism between different flakes, which exhibit 3D Mott variable-range hopping conduction at any temperature