Search

Complex systems are difficult to manage, operate and maintain. This is why we see teams of highly specialised engineers in industries such as aerospace, nuclear and subsurface. Condition based monitoring is also employed to maximise the efficiency of extensive maintenance programmes instead of using periodic maintenance. A level of automation is often required in such complex engineering platforms in order to effectively and safely manage them. Advances in Artificial Intelligence related technologies have offered greater levels of automation but this potentially pivots the weight of decision making away from the operator to the machine. Implementing AI or complex algorithms into a platform can mean that the Operators' control over the system is diminished or removed altogether. For example, in the Boeing 737 Air Max Disaster, AI had been added to a platform and removed the operators' control of the system. This meant that the operator could not then move outside the extremely reserved, algorithm defined, "envelope" of operation. This paper analyses the challenges of AI driven condition based monitoring where there is a potential to see similar consequences to those seen in control engineering. As the future of society becomes more about algorithm driven technology, it is prudent to ask, not only whether we should implement AI into complex systems, but how this can be achieved ethically and safely in order to reduce risk to life. [ABSTRACT FROM AUTHOR]

Drilling is a material removal process that introduces the plastic deformation and stresses around the hole. When large amounts of drilling stresses are added up, there will be deformation in the aerostructural assembly. This paper presents an aerostructural assembly deformation predicting method considering drilling-induced stresses around the riveting hole. Drilling-induced stresses are simulated with additional temperature fields. The assembly of the two riveted plates are considered to illustrate effects of drilling-induced stresses coupling and validate the proposed model. The simulation and experimental results show that one hole's drilling-induced stresses have negligible impact on the riveting deformation, while a lot of holes' drilling-induced stresses must be considered in assembling. When a lot of drillinginduced stresses are added up, there will be significant deformation in the aircraft's structure. The deformation predicting method outlined in this paper will enhance the understanding of the compliant components deformation resulting from the drilling stresses and help systematically improve the precision control efficiency in the civil aircraft industry. [ABSTRACT FROM AUTHOR]

This paper presents a contribution to the diagnosis of scientificresearch evaluation in Brazil, supported by a national database dubbed "Qualis". Capes is the governmental institution in charge of the development and management of this database, which presents the classification of journals and is an important tool for the improvement of Brazilian scientific research. The present paper identifies the major difficulties in research evaluation and provides an analysis of the latest changes regarding the criteria which are applied within the field of "Engineering III", which includes: Aerospace Engineering, Production Engineering, Mechanical Engineering, Petroleum Engineering and Naval/Ocean Engineering. The analysis comprises a discussion of proposals for improvement and a conceptual map showing synthetically the interrelationships among the concepts utilized in the study. In addition, it presents some suggestions which are specific for the context of Operations Research. [ABSTRACT FROM AUTHOR]

The arguments, analysis and observations in this paper are based on 10 years of research with partners in the European and US aerospace and defence industries. During this period, the authors were part of a team of researchers who were seeking to develop a new methodology and tool set for project management, particularly aimed at large aerospace projects. The research was motivated by the seemingly ubiquitous reality of project failure, with large engineering projects apparently always late and over budget. Here the authors focus on aerospace and defence, but the problems are generic across all branches of engineering. In their view, aerospace and defence have more excuses than most, because not only are the projects huge, but also they are globally distributed and highly complex. As work progressed, a fundamental conundrum emerged. Through discussions with project managers and assessment of the teams that were undertaking the projects, it became obvious that they were well educated, intelligent, highly motivated and very capable people. So why were so many projects going wrong? And it was not just aerospace and defence, as projects were failing in many different sectors and in numerous geographic locations. Obviously the problems were not to do with incompetence, as they were clearly so generic. As a result, the authors focused their analysis on factors inherent in the way all major projects are undertaken. The ultimate finding has been that the very technology available for managing projects today is inadequate. As argued within the paper, modern, complex projects cannot be planned and executed using 50-year-old project management tools. The paper tells the story of what is wrong with the current technology and how and why it needs to change. The authors are well aware that there are also cultural problems in project management, but many of these are exacerbated by the use of inadequate tools. [ABSTRACT FROM AUTHOR]

The article presents a list of papers on engineering presented at various conferences held in different parts of the world. Some of the papers are "Development of NDT Sensors for Health Monitoring of Aerospace Structures," by J. Barshinger and colleagues "Continuing Professional Development-Managing Your Career," by P. Kolbe and "Twelve Steps to Effective in the Ditch NDE," by R. Kania.

One key issue in the simulation of bare electrodynamic tethers (EDTs) is the accurate and fast computation of the collected current, an ambient dependent operation necessary to determine the Lorentz force for each time step. This paper introduces a novel semianalytical solution that allows researchers to compute the current distribution along the tether efficient and effectively under orbital-motion-limited (OML) and beyond OML conditions, i.e., if tether radius is greater than a certain ambient dependent threshold. The method reduces the original boundary value problem to a couple of nonlinear equations. If certain dimensionless variables are used, the beyond OML effect just makes the tether characteristic length L* larger and it is decoupled from the current determination problem. Avalidation of the results and a comparison of the performance in terms of the time consumed is provided, with respect to a previous ad hoc solution and a conventional shooting method. [ABSTRACT FROM AUTHOR]

In this paper, according to ISO 2631/1, 1997, the influence of the mechanical vibrations on human health is evaluated and assessed with four methods: the health guidance caution zones (HGCZ), the estimated vibration dose value (eVDV), the fourth power vibration dose value (VDV), a combination of various methods presented in literature. The normative refers to the HGCZ, which involves the average RMS vibration emission level and its exposure time during a given working day. Values of crest factor for the operator seat showed that Z-axis was the more solicited, even if all the crest factor values are below 9. Results of mechanical vibration in respect of comfort and health, according with the method of the HGCZ, showed that only case B, at higher forward speed, does not exceed the lower boundary of the zone. According to the fourth power vibration dose method and ratios for comparison of basic and additional methods of evaluation, the results showed that only case A, at lower forward speed, does not exceeded 1.25. [ABSTRACT FROM AUTHOR]

This paper investigates the steady hydromagnetic three-dimensional boundary layer flow of Maxwell fluid over a bidirectional stretching surface. Both cases of prescribed surface temperature (PST) and prescribed surface heat flux (PHF) are considered. Computations are made for the velocities and temperatures. Results are plotted and analyzed for PST and PHF cases. Convergence analysis is presented for the velocities and temperatures. Comparison of PST and PHF cases is given and examined. [ABSTRACT FROM AUTHOR]

This paper presents a new navigation guidance law for a pursuer to intercept a moving target with a prescribed impact direction in space. The proposed guidance law makes the pursuer follow a relatively circular trajectory with respect to the target. The performance of the proposed law does not depend on initial arrangement geometry and the magnitude of acceleration command is essentially bounded even at impact time. Numerical simulations confirmed technical soundness of mathematical developments and good performance of our new law even for maneuvering targets. [ABSTRACT FROM AUTHOR]

The main factor in design and operation of aircraft is safety of an airplane. The “safety culture” developed in aeronautics results in detailed regulations and certification procedures in all phases of aircraft design and operation. But despite that, aircraft safety depends on several unpredictable factors, such as the hostile actions both inside and outside of the aircraft. When failures occur during the flight, the most important actions are aimed at maintaining the aircraft controllability. The aircraft control system should be fault tolerant and ensure aircraft controllability in the event of the failure of a part of the flight control system. In this paper the influence of control surface failures on autopilot operation has been investigated. The autopilot is designed for business jet airplanes and fulfills the main functions of the real autopilot system in longitudinal and lateral directions. The autopilot structure allows implementation of various methods of reconfiguration for aircraft protection. [ABSTRACT FROM AUTHOR]

Abstract: There are huge potential applications of 3-D braided composite in aerospace engineering because of the non-delamination feature of the composite under impact loading. This paper presents the analysis of energy absorption features of 3-D braided composite under compression with different strain rates. The 3-D 4-step rectangular braided composite coupons were tested on a material tester MTS 810.23 and a split Hopkinson pressure bar (SHPB) apparatus to obtain out-of-plane and in-plane compression stress vs. strain curves at quasi-static and high strain rate state. The failure modes and energy absorption features of the 3-D braided composite under different strain rates were analyzed both in time domain and frequency domain. The energy absorbed by the 3-D braided composite increases with the strain rate. From fast Fourier transform (FFT) analysis of compression stress vs. time histories, the power of energy absorption of the 3-D braided composite increases with strain rate and mostly concentrate on the high frequency region. While for quasi-static compression, the power distributes in very narrow frequency region and also is less than that in high strain rates. This feature corresponds to the different damage and energy absorption mechanisms of the 3-D braided composite under quasi-static and high strain rate compression. [Copyright &y& Elsevier]

The vibration absorber has been used for vibration control purposes in many sectors of engineering from aerospace, to automotive to civil, for the past 100 years or so. A limitation of the device, however, is that it acts like a notch filter, only being effective over a narrow band of frequencies. Recent developments have overcome this limitation by making it possible to tune the device over a range of frequencies. This has been achieved by incorporating a variable stiffness element that can be adjusted in real-time. In this paper, some ways in which stiffness change can be achieved in practice are reviewed and some examples of prototype adaptive tuned vibration absorbers (ATVAs) are described. A simple control scheme to automatically tune an ATVA is also presented. [ABSTRACT FROM AUTHOR]

When designing aerospace systems, it is essential to provide crucial failure information for failure prevention. Failure modes and effects types of analyses and prior engineering knowledge and experience are commonly used to determine the potential modes of failures a product might encounter during its lifetime. When new products are being considered and designed, this knowledge and information is expanded upon to help designers extrapolate based on their similarity with existing products and the potential design tradeoffs. In this work, we aim to enhance this process by providing design-aid tools which derive similarities between functionality and failure modes. Specifically, this paper presents the theoretical foundations of a matrix-based approach to derive similarities that exist between different failure modes, by mapping observed failure modes to the functionality of each component, and applies it to a simple design example. The function–failure mode method is proposed to design new products or redesign existing ones with solutions for functions that eliminate or reduce the potential of a failure mode. [ABSTRACT FROM AUTHOR]