Search results for "Aerospace"
showing 10 items of 450 documents
Malthusian checks in pre-industrial Sweden and Finland: a comparative analysis of the demographic regimes
2015
In this article, the existence of the Malthusian preventive and positive checks in pre-industrial Sweden and Finland are studied using demographic and economic data from circa 1750–1860. By applying time series analysis, we are able to identify strong preventive and positive checks for Sweden. The preventive check is considered to work both directly through births and indirectly through marriages. Although the Finnish data also indicate the existence of the preventive check, the positive check is only detected with differenced data. Our findings contradict the initial hypothesis that, due to poverty, Finland would display a higher sensitivity of mortality to living standards than Sweden. In…
Resource Allocation and Computation Offloading for Multi-Access Edge Computing With Fronthaul and Backhaul Constraints
2021
Edge computing is able to provide proximity solutions for the future wireless network to accommodate different types of devices with various computing service demands. Meanwhile, in order to provide ubiquitous connectivities to massive devices over a relatively large area, densely deploying remote radio head (RRH) is considered as a cost-efficient solution. In this work, we consider a vertical and heterogeneous multi-access edge computing system. In the system, the RRHs are deployed for providing wireless access for the users and the edge node with computing capability can process the computation requests from the users. With the objective to minimize the total energy consumption for proces…
Transmission Optimization and Resource Allocation for Wireless Powered Dense Vehicle Area Network With Energy Recycling
2022
The wireless-powered communication paradigm brings self-sustainability to the on-vehicle sensors by harvesting the energy from radiated radio frequency (RF) signals. This paper proposes a novel transmission and resource allocation strategy for the scenario where multiple wireless powered vehicle area networks (VAN) co-existed with high density. The considered multi-VAN system consists of a remote master access point (MAP), multiple on-vehicle hybrid access points (HAPs) and sensors. Unlike previous works, we consider that the sensors can recycle the radiated radio frequency energy from all the HAPs when HAPs communicate with MAP, so the dedicated signals for energy harvesting (EH) are unnec…
Design and Assessment of Optimized EMI Filters for Avionic Applications
2018
This paper presents a procedure to design EMI filters to reduce the electromagnetic disturbances generated by electrical apparatus used in avionic environment. The method proposed can be useful to save weight and size of the attenuation systems, and keep their effectiveness in agreement with the standard requirements. A design of a set of different filters with different topological characteristics is presented for a case study about an electrical actuator used for an aircraft onboard application. Performances and reliabilities of the attenuation systems are assessed by suitable full compliance experimental tests.
Relevance of trade facilitation in emerging countries exports
2012
The objective of this article is to analyse trade flows in emerging nations with a maritime boundary, where trade facilitation plays a decisive role in their international development. In order to detect possible patterns in performance, we apply the economic approach of gravity models using the World Bank Logistic Performance Index (LPI) as a good proxy of trade facilitation. The results of the estimation lead to the conclusion that the more complex the transportation of goods is, the more influential the logistics indicator, trade facilitation being most prominent in Middle East exporters.
Hidden attractors in Chua circuit: mathematical theory meets physical experiments
2022
AbstractAfter the discovery in early 1960s by E. Lorenz and Y. Ueda of the first example of a chaotic attractor in numerical simulation of a real physical process, a new scientific direction of analysis of chaotic behavior in dynamical systems arose. Despite the key role of this first discovery, later on a number of works have appeared supposing that chaotic attractors of the considered dynamical models are rather artificial, computer-induced objects, i.e., they are generated not due to the physical nature of the process, but only by errors arising from the application of approximate numerical methods and finite-precision computations. Further justification for the possibility of a real exi…
Complex dynamics, hidden attractors and continuous approximation of a fractional-order hyperchaotic PWC system
2018
In this paper, a continuous approximation to studying a class of PWC systems of fractionalorder is presented. Some known results of set-valued analysis and differential inclusions are utilized. The example of a hyperchaotic PWC system of fractional order is analyzed. It is found that without equilibria, the system has hidden attractors.
On Apache Log4j2 Exploitation in Aeronautical, Maritime, and Aerospace Communication
2022
Apache Log4j2 is a prevalent logging library for Java-based applications. In December 2021, several critical and high-impact software vulnerabilities, including CVE-2021-44228, were publicly disclosed, enabling remote code execution (RCE) and denial of service (DoS) attacks. To date, these vulnerabilities are considered critical and the consequences of their disclosure far-reaching. The vulnerabilities potentially affect a wide range of internet of things (IoT) devices, embedded devices, critical infrastructure (CI), and cyber-physical systems (CPSs). In this paper, we study the effects and feasibility of exploiting these vulnerabilities in mission-critical aviation and maritime environment…
Implicit regulation for automotive variators
2001
A well-known practice uses mechanical variators to realize the so-called continuously variable transmissions (CVTs) for automotive application. A remarkable problem for one of the most used CVTs is given by the hydraulic control of the axial thrust on the half-pulleys that is necessary for torque transmission. It involves a heavy decrease in transmission efficiency. In the present paper, the possible production of the required axial thrust by a simple spring to eliminate hydraulic losses is analysed. It is shown that the power capacity of such a regulated variator is near to the maximum possible, and the belt torque loss is always considerably lower than the sum of the belt and pump losses…
Inspiratory muscle training combined with pursed lip technique in women with chronic osbtructive pulmonary disease: a case study.
2020
Objective. To improve pulmonary function, exercise capacity and quality of life of two women with Chronic Obstructive Pulmonary Disease (COPD). Material and Methods. Study of two clinical cases, both women. An intervention of 8 weeks was performed, in which the patients performed 3 weekly sessions, of which 1 was performed with supervision of the physiotherapist and 2 sessions were performed at home. The treatment sessions consisted of inspiratory muscle training with an inspiratory threshold and controlled breathing exercises with the pursed lip technique. Results. Quality of life of both women improved at the end of the study. In the woman with severe COPD, Maximal Inspiratory Pressure (M…