Search results for "Research"
showing 10 items of 25967 documents
Decomposition and Mean-Field Approach to Mixed Integer Optimal Compensation Problems
2016
Mixed integer optimal compensation deals with optimization problems with integer- and real-valued control variables to compensate disturbances in dynamic systems. The mixed integer nature of controls could lead to intractability in problems of large dimensions. To address this challenge, we introduce a decomposition method which turns the original n-dimensional optimization problem into n independent scalar problems of lot sizing form. Each of these problems can be viewed as a two-player zero-sum game, which introduces some element of conservatism. Each scalar problem is then reformulated as a shortest path one and solved through linear programming over a receding horizon, a step that mirro…
Clothoid-Based Three-Dimensional Curve for Attitude Planning
2019
Interest in flying robots, also known as unmanned aerial vehicles (UAVs), has grown during last years in both military and civil fields [1, 2]. The same happens to autonomous underwater vehicles (AUVs) [3]. These vehicles, UAVs and AUVs, offer a wide variety of possible applications and challenges, such as control, guidance or navigation [2, 3]. In this sense, heading and attitude control in UAVs is very important [4], particularly relevant in airplanes (fixed-wing flying vehicles), because they are strongly non-linear, coupled, and tend to be underactuated systems with non-holonomic constraints. Hence, designing a good attitude controller is a difficult task [5, 6, 7, 8, 9], where stabilit…
Conceptual Key Competency Model for Smart Factories in Production Processes
2020
Abstract Background and Purpose: The aim of the study is to develop a conceptual key competency model for smart factories in production processes, focused on the automotive industry, as innovation and continuous development in this industry are at the forefront and represent the key to its long-term success. Methodology: For the purpose of the research, we used a semi-structured interview as a method of data collection. Participants were segmented into three homogeneous groups, which are industry experts, university professors and secondary education teachers, and government experts. In order to analyse the qualitative data, we used the method of content analysis. Results: Based on the anal…
Experimental Research on the Cutting of Metal Materials by Electrical Discharge Machining with Contact Breaking with Metal Band as Transfer Object
2020
The scientific paper presents practical research carried out by a mixed team of Romanian researchers from universities and the business environment. The research consists in applying the process of cutting metallic materials through electrical discharge machining with contact breaking using a metal band as a transfer object. The research was implemented with the help of a specially designed installation in the laboratory and subsequently all the necessary steps were taken to obtain the patent for it. Various metallic materials were cut using this process, but first of all, high alloy steels. In the global research conducted by the authors, active experimental programs and classic experiment…
The magnitude of a product recall: offshore outsourcing vs. captive offshoring effects
2018
The escalation in product recalls in recent years is attributed to the rise of globalisation and associated challenges of offshoring. Extant SCM research suggests that product recalls have a significant negative impact on financial performance, but gaps exist relative to the managerial actions to minimise their impact. Recall response strategies have become more important in the press, given that a single recall may result in the mandatory withdrawal of millions of products from the market, with firms incurring enormous logistics costs and brand damage. In this study, we address this gap in the research, and using a measure of product recall defined as the volume of products withdrawn from …
A proposed mapping method for aligning machine execution data to numerical control code
2019
The visions of the digital thread and smart manufacturing have boosted the potential of relating downstream data to upstream decisions in design. However, to date, the tools and methods to robustly map across the related data representations is significantly lacking. In response, we propose a mapping technique for standard manufacturing data representations. Specifically, we focus on relating controller data from machining tools in the form of MTConnect, an emerging standard that defines the vocabulary and semantics as well as communications protocols for execution data, and G-Code, the most widely used standard for numerical control (NC) instructions. We evaluate the efficacy of our mappin…
Standards Based Generation of a Virtual Factory Model
2016
International audience; Developing manufacturing simulation models usually requires experts with knowledge of multiple areas including manufacturing, modeling, and simulation software. The expertise requirements increase for virtual factory models that include representations of manufacturing at multiple resolution levels. This paper reports on an initial effort to automatically generate virtual factory models using manufacturing configuration data in standard formats as the primary input. The execution of the virtual factory generates time series data in standard formats mimicking a real factory. Steps are described for auto- generation of model components in a software environment primari…
Creating a questionnaire for a scientific study
2016
Using questionnaires has become a permanent part of collecting data in scientific studies within the sphere of human sciences as well as other disciplines. It has been utilized already for nearly a century in collecting data. The first questionnaires were carried out on paper but nowadays there are e-questionnaires alongside it which can be carried out through e-mail or published on a social media platform (for example, Facebook). An often used method is also a survey which is carried out with a research project's own web page, association or company etc. A questionnaire has been considered as an actual scientific method of data collection since 1930s. However, it was already used a little …
Challenges influencing the safety of migrant workers in the construction industry: A qualitative study in Italy, Spain, and the UK
2021
Abstract The construction industry is notoriously high risk for accidents, injuries, and deaths, particularly for non-national or migrant workers, who comprise a significant proportion of the workforce. This paper presents an international, qualitative study focused on exploring the challenges which influence the safety of migrant construction workers in Italy, Spain, and the UK. Based on a comprehensive review of the literature, we formulated two research questions about the challenges relating to safety that migrant workers face and the challenges to safety training effectively improving migrant workers’ safety behaviours. We present our template analysis of semi-structured interviews and…
Shelf life-based inventory management policy for RF monitored warehouse
2018
Post-harvest losses of perishable products strongly depend on inefficiencies of the entire supply chain. In particular, these inefficiencies can be reduced by optimizing the warehouse management, taking into account the remaining shelf life of the product, and matching it to the requirements of the subsequent part of the handling chain. The replacement of First In First Out picking rule with Last Shelf Life First Out policy has been proved to improve the overall performance of the supply chain. The practicability of such approach is related to the possibility of monitoring the deterioration rate of the products and of predicting the residual shelf-life, that is mainly influenced by harvesti…