Eficiência das Ferrovias Especializadas em Transporte de Minério de Ferro e Pelotas

ABSTRACT Objective: the objective is to compare the relative efficiency of the railways specialized in transporting iron ore (MFe) and pellets (PLMFe), which are part of the assets of mining companies and pellet plants considering the 2016 scenario. Methods: the methods used were the data envelopment analysis (DEA) technique, with the application of the output-oriented constant returns scale (CRS) model; the initial combinatorial multicriteria method for choosing the input variables; and Tobit regression as a validation strategy for the DEA model. Results: of the twelve railways evaluated, three railways were identified as efficient: Estrada de Ferro Carajás, Fortescue, and Mount Newman. Conclusions: the applied model was considered a good method to evaluate the efficiency of railways specialized in transporting MFe and PLMFe, as it determined the efficiency of each railway, suggesting the necessary increase in the output variable or adjustments in the input variables so that the railways reach the efficiency frontier. With that, companies can use the results of this study to guide future improvements to make their railways more efficient or maintain them on the frontier of efficiency.

The Efficiency of Railways Specialized in Transporting Iron Ore and Pellets

ABSTRACT Objective: the objective is to compare the relative efficiency of the railways specialized in transporting iron ore (MFe) and pellets (PLMFe), which are part of the assets of mining companies and pellet plants considering the 2016 scenario. Methods: the methods used were the data envelopment analysis (DEA) technique, with the application of the output-oriented constant returns scale (CRS) model; the initial combinatorial multicriteria method for choosing the input variables; and Tobit regression as a validation strategy for the DEA model. Results: of the twelve railways evaluated, three railways were identified as efficient: Estrada de Ferro Carajás, Fortescue, and Mount Newman. Conclusions: the applied model was considered a good method to evaluate the efficiency of railways specialized in transporting MFe and PLMFe, as it determined the efficiency of each railway, suggesting the necessary increase in the output variable or adjustments in the input variables so that the railways reach the efficiency frontier. With that, companies can use the results of this study to guide future improvements to make their railways more efficient or maintain them on the frontier of efficiency.

Predicting Corrosion Delamination Failure in Active Implantable Medical Devices: Analytical Model and Validation Strategy

The ingress of body fluids or their constituents is one of the main causes of failure of active implantable medical devices (AIMDs). Progressive delamination takes its origin at the junctions where exposed electrodes and conductive pathways enter the implant interior. The description of this interface is considered challenging because electrochemically-diffusively coupled processes are involved. Furthermore, standard tests and specimens, with clearly defined 3-phase boundaries (body fluid-metal-polymer), are lacking. We focus on polymers as substrate and encapsulation and present a simple method to fabricate reliable test specimens with defined boundaries. By using silicone rubber as standard material in active implant encapsulation in combination with a metal surface, a corrosion-triggered delamination process was observed that can be universalised towards typical AIMD electrode materials. Copper was used instead of medical grade platinum since surface energies are comparable but corrosion occurs faster. The finding is that two processes are superimposed there: First, diffusion-limited chemical reactions at interfaces that undermine the layer adhesion. The second process is the influx of ions and body fluid components that leave the aqueous phase and migrate through the rubber to internal interfaces. The latter observation is new for active implants. Our mathematical description with a Stefan-model coupled to volume diffusion reproduces the experimental data in good agreement and lends itself to further generalisation.

Establishment of a specimen panel for the decentralised technical evaluation of the sensitivity of 31 rapid diagnostic tests for SARS-CoV-2 antigen, Germany, September 2020 to April 2021

Introduction The detection of SARS-CoV-2 with rapid diagnostic tests (RDT) has become an important tool to identify infected people and break infection chains. These RDT are usually based on antigen detection in a lateral flow approach. Aim We aimed to establish a comprehensive specimen panel for the decentralised technical evaluation of SARS-CoV-2 antigen rapid diagnostic tests. Methods While for PCR diagnostics the validation of a PCR assay is well established, there is no common validation strategy for antigen tests, including RDT. In this proof-of-principle study we present the establishment of a panel of 50 pooled clinical specimens that cover a SARS-CoV-2 concentration range from 1.1 × 109 to 420 genome copies per mL of specimen. The panel was used to evaluate 31 RDT in up to six laboratories. Results Our results show that there is considerable variation in the detection limits and the clinical sensitivity of different RDT. We show that the best RDT can be applied to reliably identify infectious individuals who present with SARS-CoV-2 loads down to 106 genome copies per mL of specimen. For the identification of infected individuals with SARS-CoV-2 loads corresponding to less than 106 genome copies per mL, only three RDT showed a clinical sensitivity of more than 60%. Conclusions Sensitive RDT can be applied to identify infectious individuals with high viral loads but not to identify all infected individuals.

Recommended Best Practices for Lyophilization Validation 2021 Part II: Process Qualification and Continued Process Verification

This work describes the lyophilization process validation and consists of two parts. Part one (Part I: Process Design and Modeling) focuses on the process design and is described in the previous paper, while the current paper is devoted to process qualification and continued process verification. The goal of the study is to show the cutting edge of lyophilization validation based on the integrated community-based opinion and the industrial perspective. This study presents best practices for batch size determination and includes the effect of batch size on drying time, process parameters selection strategies, and batch size overage to compensate for losses during production. It also includes sampling strategies to demonstrate batch uniformity as well as the use of statistical models to ensure adequate sampling. Based on the LyoHUB member organizations survey, the best practices in determining the number of PPQ runs are developed including the bracketing approach with minimum and maximum loads. Standard practice around CQA and CPP selection is outlined and shows the advantages of using control charts and run charts for process trending and quality control. The case studies demonstrating the validation strategy for monoclonal antibody and the impact of the loading process on the lyophilization cycle and product quality as well as the special case of lyophilization for dual-chamber cartridge system are chosen to illustrate the process validation. The standard practices in the validation of the lyophilization process, special lyophilization processes, and their impact on the validation strategy are discussed. Graphical Abstract

Thermoelectric-based cooling system for high-speed motorized spindle II: Optimization and validation strategy

With the development of motorized spindle, the cooling effect and the distribution of cooling capacity become the crucial problem of cooling system. An optimization method for ThermoElectric-based Cooling System (TECS) is proposed based on the conservation of energy to distribute the cooling capacity. The main strategy of the proposed optimization method is to make the cold and heat input at different regions of the spindle sleeve equal in real-time through optimizing the contact area between the Heat Conduction Sleeve (HCS) and spindle sleeve. The numerical simulation and thermal characteristics experiments are carried to verify the effect of the proposed optimization method and the TECS. The simulation and experimental results show that the maximum temperature rise and thermal elongation of the TECS-based motorized spindle are reduced 56.7% and 58.6% compared with water-cooled motorized spindle, and the temperature distribution of the spindle sleeve is more uniform. It is meaningful to improve the accuracy of motorized spindle.

Design and Implementation of an IMC-1DOF Controller Applied to MPPT Photovoltaic Systems Using ZVS Full-Bridge DC-DC Converter

This paper presents the design of an Internal Model Control – 1 Degree of Freedom (IMC-1DOF) controller applied to a Zero Voltage Switching (ZVS) Full-Bridge DC-DC converter that will be used in photovoltaic systems for Maximum Power Point Tracking (MPPT), with the objective of developing a single phase micro inverter. It will be presented the mathematical modeling of this converter to control the input voltage aiming the application in MPPT and the design of the respective controller IMC-1DOF. The proposal testing and validation strategy was performed by comparison with a PI compensator. The performance of both controllers are evaluated and discussed.

Cybersecurity attacks on CAN bus based vehicles: a review and open challenges

PurposeNowadays, connected vehicles are becoming quite complex systems which are made up of different devices. In such a vehicle, there are several electronic control units (ECUs) that represent basic units of computation. These ECUs communicate with each other over the Controller Area Network (CAN) bus protocol which ensures a high communication rate. Even though it is an efficient standard which provides communication for in-vehicle networks, it is prone to various cybersecurity attacks. This paper aims to present a systematic literature review (SLR) which focuses on potential attacks on CAN bus networks. Then, it surveys the solutions proposed to overcome these attacks. In addition, it investigates the validation strategies aiming to check their accuracy and correctness.Design/methodology/approachThe authors have adopted the SLR methodology to summarize existing research papers that focus on the potential attacks on CAN bus networks. In addition, they compare the selected papers by classifying them according to the adopted validation strategies. They identify also gaps in the existing literature and provide a set of open challenges that can significantly improve the existing works.FindingsThe study showed that most of the examined papers adopted the simulation as a validation strategy to imitate the system behavior and evaluate a set of performance criteria. Nevertheless, a little consideration has been given to the formal verification of the proposed systems.Originality/valueUnlike the existing surveys, this paper presents the first SLR that identifies local and remote security attacks that can compromise in-vehicle and inter-vehicle communications. Moreover, it compares the reviewed papers while focusing on the used validation strategies.