Abstract
The research about the digital twin concept is growing worldwide, especially in the industrial sector, due to the increasing digitisation level associated to Industry 4.0. The application of the digital twin concept improves performance of a system by implementing monitoring, diagnosis, optimisation, and decision support actions. In particular, the decision-making process is very time consuming since the decision-maker is presented with hundreds of different scenarios that can be simulated and assessed in a what-if perspective. Bearing this in mind, this paper proposes to integrate a digital twin-based what-if simulation with a recommendation system to improve the decision-making cycle. The recommendation system is based on a reinforcement learning technique and takes user knowledge of the system into consideration and trust in the system recommendation. The applicability of the proposed approach is presented in an assembly line case study for recommending the best configurations for the system operation, in terms of the optimal number of AGVs (Autonomous Guided Vehicles) in various scenarios. The achieved results show its successful application and highlight the benefits of using AI-based recommendation systems for what-if simulation in digital twin systems.

Abstract
The exponential growth of documents in the web makes it very hard for researchers to be aware of the relevant work being done within the scientific community. The task of efficiently retrieving information has therefore become an important research topic. The objective of this study is to test how the efficiency of the text classification changes if different weights are previously assigned to the sections that compose the documents. The proposal takes into account the place (section) where terms are located in the document, and each section has a weight that can be modified depending on the corpus. To carry out the study, an extended version of the OHSUMED corpus with full documents have been created. Through the use of WEKA, we compared the use of abstracts only with that of full texts, as well as the use of section weighing combinations to assess their significance in the scientific article classification process using the SMO (Sequential Minimal Optimization), the WEKA Support Vector Machine (SVM) algorithm implementation. The experimental results show that the proposed combinations of the preprocessing techniques and feature selection achieve promising results for the task of full text scientific document classification. We also have evidence to conclude that enriched datasets with text from certain sections achieve better results than using only titles and abstracts.

Abstract
The smart grid is a fully automatic delivery grid for electricity power with a two-way reliable flow of electricity and information among different equipment on the grid. Smart meters and sensors monitoring the system provide a huge amount of data in various part of smart grid. To logically manage this trouble, a new lossy data compression approach for big data compression is proposed. The optimal singular value decomposition (SVD) is applied to a matrix that achieves the optimal number of singular values to the sending process, and the other ones will be neglected. This goal is done due to the quality of retrieved data and the compression ratio. In the presented scheme, to implement the optimization framework, various intelligent optimization methods are used to determine the number of optimal values in the elimination stage. The efficiency and capabilities of the proposed method are examined using a wide range of data types, from electricity market data to image processing benchmarks. The comparisons show that the compression level obtained by the proposed method can dominate the points given by the existing SVD rank reduction methods. Also, as the other finding of this article, the performance of the rank reduction methods depends on the application and data types. It means that a rank reduction method can reveal a good performance in one application and performs unacceptably for another purpose. So, the optimized rank reduction can pave the way toward a robust and reliable performance.

Abstract
This study aims to address an emerging area of application of agile methodologies outside the traditional technological environment, particularly outside the context of software engineering. In this sense, it intends to understand and contextualise the problems and challenges that are posed by traditional methodologies and explore how agile methodologies can complement or substitute to traditional methodologies in non-technological environments. For this purpose, a qualitative study was performed through three case studies operating in different sectors of activity like digital marketing, management consulting, and tourism. The findings indicate that both traditional and agile methodologies can coexist, and it is common to find hybrid methodologies that are adopted and customised according to the needs of each project and client. Furthermore, it was possible to conclude that following agile practices that make sense to the cultural values of the organisation is more important than adopting a specific agile methodology. Copyright © 2021 Inderscience Enterprises Ltd.

Abstract
We carry out the first provable security analysis of the new FIDO2 protocols, the promising FIDO Alliance's proposal for a standard for passwordless user authentication. Our analysis covers the core components of FIDO2: the W3C's Web Authentication (WebAuthn) specification and the new Client-to-Authenticator Protocol (CTAP2). Our analysis is modular. For WebAuthn and CTAP2, in turn, we propose appropriate security models that aim to capture their intended security goals and use the models to analyze their security. First, our proof confirms the authentication security of WebAuthn. Then, we show CTAP2 can only be proved secure in a weak sense; meanwhile, we identify a series of its design flaws and provide suggestions for improvement. To withstand stronger yet realistic adversaries, we propose a generic protocol called sPACA and prove its strong security; with proper instantiations, sPACA is also more efficient than CTAP2. Finally, we analyze the overall security guarantees provided by FIDO2 and WebAuthn+sPACA based on the security of their components. We expect that our models and provable security results will help clarify the security guarantees of the FIDO2 protocols. In addition, we advocate the adoption of our sPACA protocol as a substitute for CTAP2 for both stronger security and better performance.

Abstract
A B S T R A C T Power Distribution Systems usually rely on closed and fixed communication networks due to the strict requirements they must comply with. With the appearance of new communication technologies that can contribute to the assurance of those requirements (for example, 5G), open networks can be used for such systems, decreasing the overall cost of maintaining and upgrading the communication network. Although, shifting from closed communication environments to networks integrated with the Internet using 5G communication environments can expose these systems to severe threats, since they were developed to operate under closed networks not addressing security by default. This paper analyses the security requirements for Power Distribution Systems operating on open networks, identifying the gap between such systems and the existing security mechanisms. From this analysis, we present a solution based on low cost off-the-shelf hardware, composed by a security library and a bridging device, intended to act as a security gateway for Intelligent Electronic Devices (IEDs) in Power Distribution Systems. We also evaluate the functionality of our security gateway, and analyse its impact on the stringent performance requirements of such systems.