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Oblique impacts which occur in many situations in mineral industries leads to material removal and fail of mechanical parts. Studies will be helpful in optimal design to have minimum machine malfunctions.

In the present work, the Hertz-Di Maio Di Renzo nonlinear model of contact is used to simulate the impact phenomenon as a micro-sliding process. The modified Archard equation is used to evaluate wear over the impact. The wear coefficient is evaluated by a pin-disk machine. An impact-wear tester is used to validate the model results.

The measurements indicate an increase in surface hardness because of the several impacts. It is considered in the wear predictive model.

The model predictions compared with the experimental data, obtained from the impact-wear tester, show that the model well predicts the impact wear and can be used as a predictive tool to study the practical design problems and to explain some phenomena associated with the percussive impact.

The Olivetti SIGMA robot has been pioneering robot assembly for five years. In this article the experience gained and the problems that have occurred are discussed.

The purpose of this paper is to present an image based method for estimating the 3D motion of rigid particles from high‐speed video footage (HSV). The computed motion can be used as either a means to generate quantitative feedback for a process or to validate the accuracy of discrete element method (DEM) simulation models.

Experiments consist of a diamond impacting an angled plate and video is captured at 4,000 frames per second. Simple image analysis is used to track the particle in each frame and to extract its 2D silhouette boundary. Using an approximate 3D model of the particle generated from a multi‐camera setup, a pose estimation scheme based on silhouette consistency is used in conjunction with a rigid body model to compute the 3D motion.

Under reasonable conditions, the method can reliably estimate the linear and angular motion of the particle to within 1 per cent of their true values.

As an example application, we demonstrate how the method can be used to validate DEM simulations of simple impact experiments captured with HSV, providing valuable insight towards further development. In particular, we investigate the effects of shape representation through sphere‐clumping and the applicability of different contact models.

The novelty of our method is its ability to accurately compute the motion associated with a real world interaction, such as an impact, which provides numerical ground truth at an individual particle level. While similar schemes have been attempted with ideal particles (e.g. spheres), the resulting models do not naturally extend to realistic particle shapes. Since our method can track real particles, real‐world processes can be better quantified.

A consistent implementation of the general computational framework of unified second-order time accurate integrators via the well-known GSSSS framework in conjunction with the traditional Finite Difference Method is presented to improve the numerical simulations of reactive two-phase flows.

In the present paper, the phase interaction evaluation in the present implementation of the reactive two-phase flows has been derived and implemented to preserve the consistency of the correct time level evaluation during the time integration process for solving the two phase flow dynamics with reactions.

Numerical examples, including the classical Sod shock tube problem and a reactive two-phase flow problem, are exploited to validate the proposed time integration framework and families of algorithms consistently to second order in time accuracy; this is in contrast to the traditional practices which only seem to obtain first-order time accuracy because of the inconsistent time level implementation with respect to the interaction of two phases. The comparisons with the traditional implementation and the advantages of the proposed implementation are given in terms of the improved numerical accuracy in time. The proposed approaches provide a correct numerical simulation implementation to the reactive two-phase flows and can obtain better numerical stability and computational features.

The new algorithmic framework and the consistent time level evaluation extended with the GS4 family encompasses a multitude of past and new schemes and offers a general purpose and unified implementation for fluid dynamics.

This paper aims to simulate a punch shear test of partly consolidated ice ridge keel by using a three-dimensional discrete element method. The authors model the contact forces between discrete ice blocks with Hertz–Mindlin contact model. For freeze bonds between the ice blocks, the authors apply classical linear cohesion model with few modifications. Based on punch shear test simulations, the authors are able to determine the main characteristics of an ice ridge from the material parameters of the ice and freeze bonds.

The authors introduced a discrete model for ice that can be used for modelling of ice ridges. The authors started with short introduction to current status with ice ridge modelling. Then they introduced the model, which comprises Hertz–Mindlin contact model and freeze bond model with linear cohesion and softening. Finally, the authors presented the numerical results obtained using EDEM is commercial Discrete Element Modeling software (EDEM) and analysed the results.

The Hertz–Mindlin model with cohesive freeze bonds and linear softening is a reasonable model for ice rubble. It is trivial that the ice blocks within the ice ridge are not spherical particles, but according to results, the representation of ice blocks as spheres gave promising results. The simulation results provide information on how the properties of freeze bond affect the results of punch shear test. Thus, the simulation results can be used to approximate the freeze bonds properties within an ice ridge when experimental data are available.

As the exact properties of ice rubble are unknown, more research is required both in experimental and theoretical fields of ice rubble mechanics.

Based on this numerical study, the authors are able to determine the main characteristics of an ice ridge from material parameters of ice and freeze bonds. Furthermore, the authors conclude that the model creates a promising basis for further development in other applications within ice mechanics.

The implementation of Smart Manufacturing (SM) is deemed a key enabler in the enhancement of manufacturing competitiveness and performance. Nevertheless, SM's repercussion on consumer perceptions and the contextualization of SM's performance-enhancement effects remain undetermined and have yet to be clarified. This study analyzes the effect of SM on operational and customer performance. Moreover, this study explores how these relationships change depending on a firm's geography of production (i.e. national/local vs transnational operations) and the relational arrangement adopted (i.e. service-oriented vs transaction-oriented manufacturers).

This research surveys 351 Spanish manufacturing firms operating in an SM environment. The theoretical framework comprises a Multiple-Indicators Multiple-Causes (MIMIC) model and is tested using a Generalized Structural Equations Model.

The results obtained substantiate the positive effect of SM implementation on both of the performance measures analyzed (i.e. operational and customer focused). Moreover, the study reveals that while geography of production moderates the effect on a firm's operational performance, relational arrangement also does so in terms of customer performance.

This research clearly differentiates the benefits of SM depending on business context. In this regard, transnational production firms tend to gain in operational performance while service-oriented manufacturers gain in customer performance.

The purpose of this study is to define configuration requirements needed to define “harmless” small unmanned aerial systems (sUAS) by taking into account mathematical models and ballistic approaches, already defined for small projectiles and now modified, with appropriate assumptions. These safety requirements are related to structures, materials, weight and dimensions, such as the radius of curvature.

In this paper, the state-of-the-art forensic and ballistic physics models are presented, and then safety requirements are defined for sUAS. This big challenge is due to a lack of regulation because each country and each regulatory authority have published their own regulations, where the imposed requirements are different because the mathematical models, and the related assumptions, are different from one country to another. Therefore, proper assumptions are introduced in these models to obtain safety requirements to define harmless final configuration.

If the final configuration meets the requirements defined in the methodology, there are no severe injuries on the human body, in case of impact with the sUAS. In other words, the inoffensive configuration can also be used in overcrowded areas without risks for the human life.

The final configuration proposed in this paper has some design features substantially modified, compared to the conventional configuration, and in particular, the sUAS could be the first harmless multicopter certified in Italy.

This article aims to analyze the specific indicators of the circular economy (CE) in terms of analytical aspects, scope and breadth of metrics and levels of innovation associated with CE.

A literature review was developed with a sample of 125 articles, extracted from Scopus, Web of Science, ScienceDirect, Emerald, Google Scholar, Online Library, Sage, Springer, Taylor and Francis and JSTOR databases.

The results indicate the lack of integration of the social dimension and predominance of environmental indicators, lack of indicators for the meso level and concentration of metrics for the product level. Methodological criteria of validity and reliability for measurement studies are recommended, as well as paths and proposals for future research in the CE.

The study’s limitations are linked to the content and method aspects. Although the search was performed in several databases, with a significant number of articles returned compared to other reviews of the topic, the possibilities are limited by the data source and the impossibility of a broader review. The theme is not yet consolidated and this affects the linearity of the revised results. As for the method, the analysis and coding in systematic reviews involve the authors’ capacity for exploration and cognition.

The article proposes six theoretical propositions and the theoretical framework that portrays the main findings of the study and questions to drive future research in the topic.

The article points out opportunities for companies, universities and the government regarding the possibilities that can be explored to develop knowledge and practice about the field.

This research advances the CE literature by means of providing a review of the indicators, metrics and tools oriented toward the CE literature that contributes to the improvement and consolidation of the various researches in the field.

In the past decades, both civil and military applications of small unmanned aerial systems (sUASs) have been on the rise. The sUASs guarantee the performance of dangerous, dull, duly and dirty missions, according to the 4D rule. The purpose of this study is to describe, some ethical, operational and safety challenges occur owing to the use of sUASs at over-crowded areas or in emergency scenarios. After an overview of the current sUAS regulations, some strategic configuration elements will be analysed to improve these systems and to define safe and inoffensive sUASs. Nevertheless, some problems have not been completely overcome.

The unmanned vehicles are nowadays applied for different kinds of applications. Search and rescue (S&R) missions; terrain surveillance and monitoring after natural disasters, such as earthquakes and landslides; and transportation of medical equipment and cartography are some examples of the most renowned and important civil missions of sUAS. In all these scenarios, some challenges could be encountered. First, the use of sUASs could compromise the privacy of unaware citizens who are in the area of application. Moreover, even if the unmanned vehicle works according to national and international regulations, there are some hazards both for the ground operators and for the population, because these sUASs could impact the human body after a flight failure.

In this paper, current principal regulations will be analysed, identifying some differences and discrepancies among them. Moreover, some considerations about the configuration elements are introduced to define the safe use of sUASs. Nevertheless, the privacy challenge is quite complicated to be overcome definitely.

Considering some challenges related to the civil applications of sUASs, new unmanned configurations could be developed to guarantee safety and data protection of unaware people.

Accountability within the framework of circular economy (CE) is unknown even though the concept of CE is increasingly gaining momentum among governments, policymakers and academics. The purpose of this study is to investigate how accountability expresses itself in the CE.

This study draws on the institutional logics theory and adopted an exploratory qualitative study aimed at eliciting stakeholders’ perspectives on how accountability manifests in the context of CE. Data was collected through semi-structured interviews of cross section of Ghanaians. Respondents were recruited using the purposeful sampling method, and data saturation was reached with 35 respondents. Concurrent data collection and analysis were carried out, and emerging themes were investigated as the research progressed.

The results indicate that accountability manifestations take on a variety of forms and shapes through both formal and informal processes within the circularity space. The specific areas of accountability manifestations are through the social system embedded in the society, through the organization’s responsibility and transparency, through regular reporting to stakeholders using appropriate metrics, through agency and answerability to relevant stakeholders and through governance systems embedded within social interaction. Additionally, this study discovered that accountability manifestations would contribute to the firm’s sustainability by enhancing competitive advantage through stakeholder engagement, improving risk management and promoting creativity and innovation.

Given an apparent gap in the literature on circularity and accountability, as well as a call for further studies on the reflections of accountability within the CE, this study provides empirical evidence to fill these gaps.