scholarly journals Spiral trajectories induced by radial thrust with applications to generalized sails

Astrodynamics ◽  
2020 ◽  
Author(s):  
Marco Bassetto ◽  
Alessandro A. Quarta ◽  
Giovanni Mengali ◽  
Vittorio Cipolla
Keyword(s):  
Equations Of Motion ◽  
Propulsion System ◽  
Point Of View ◽  
Propulsion Systems ◽  
Spiral Trajectory ◽  
System A ◽  
Spiral Trajectories ◽  
Radial Thrust ◽  
Heliocentric Orbit

AbstractIn this study, new analytical solutions to the equations of motion of a propelled spacecraft are investigated using a shape-based approach. There is an assumption that the spacecraft travels a two-dimensional spiral trajectory in which the orbital radius is proportional to an assigned power of the spacecraft angular coordinate. The exact solution to the equations of motion is obtained as a function of time in the case of a purely radial thrust, and the propulsive acceleration magnitude necessary for the spacecraft to track the prescribed spiral trajectory is found in a closed form. The analytical results are then specialized to the case of a generalized sail, that is, a propulsion system capable of providing an outward radial propulsive acceleration, the magnitude of which depends on a given power of the Sun-spacecraft distance. In particular, the conditions for an outward radial thrust and the required sail performance are quantified and thoroughly discussed. It is worth noting that these propulsion systems provide a purely radial thrust when their orientation is Sun-facing. This is an important advantage from an engineering point of view because, depending on the particular propulsion system, a Sun-facing attitude can be stable or obtainable in a passive way. A case study is finally presented, where the generalized sail is assumed to start the spiral trajectory from the Earth’s heliocentric orbit. The main outcome is that the required sail performance is in principle achievable on the basis of many results available in the literature.

scholarly journals Installed Performance Assessment of an Array of Distributed Propulsors Ingesting Boundary Layer Flow

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Chana Goldberg ◽  
Devaiah Nalianda ◽  
Panagiotis Laskaridis ◽  
Pericles Pilidis
Keyword(s):  
Boundary Layer ◽  
Fuel Consumption ◽  
Flow Characteristics ◽  
Propulsion System ◽  
Accounting System ◽  
Propulsion Systems ◽  
Local Flow ◽  
System A ◽  
Layer Flow

Conventional propulsion systems are typically represented as uninstalled systems to suit the simple separation between airframe and engine in a podded configuration. However, boundary layer ingesting systems are inherently integrated, and require a different perspective for performance analysis. Simulations of boundary layer ingesting propulsions systems must represent the change in inlet flow characteristics, which result from different local flow conditions. In addition, a suitable accounting system is required to split the airframe forces from the propulsion system forces. The research assesses the performance of a conceptual vehicle, which applies a boundary layer ingesting propulsion system—NASA's N3-X blended wing body aircraft—as a case study. The performance of the aircraft's distributed propulsor array is assessed using a performance method, which accounts for installation terms resulting from the boundary layer ingesting nature of the system. A “thrust split” option is considered, which splits the source of thrust between the aircraft's main turbojet engines and the distributed propulsor array. An optimum thrust split (TS) for a specific fuel consumption at design point (DP) is found to occur for a TS value of 94.1%. In comparison, the optimum TS with respect to fuel consumption for the design 7500 nmi mission is found to be 93.6%, leading to a 1.5% fuel saving for the configuration considered.

scholarly journals Automatically determines the length of the dual system to a bivalent system

2018 ◽  
Vol XIX (1) ◽  
pp. 50-57
Keyword(s):  
Subsequent Development ◽  
Dual System ◽  
Point Of View ◽  
Automatic Determination ◽  
Stable States ◽  
System A ◽  
Minimum Number ◽  
System Length

From the point of view of reliability theory, a system can have two stable states: functioning and defect (bivalent system). Any system is a set of elements. Each element in this set can be found in one of the following states: operating state and fault condition. A subset of elements in the running state is called a system link if they only ensure the system works. The length of a bivalent system is equal to the minimum number of elements that the system holds. In this paper we present an algorithm for automatic determination of dual system length to a bivalent system, a Matlab script, a case study and subsequent development directions.

scholarly journals Algorithm to Automatically Determine the Length of a Bivalent System

2018 ◽  
Vol 24 (3) ◽  
pp. 83-88
Author(s):  
Paul Vasiliu
Keyword(s):  
Subsequent Development ◽  
Reliability Theory ◽  
Point Of View ◽  
Automatic Determination ◽  
Stable States ◽  
System A ◽  
Minimum Number

Abstract From the point of view of reliability theory, a system can have two stable states: functioning and defect (bivalent system). Any system is a set of elements. Each element in this set can be found in one of the following states: operating state and fault condition. A subset of elements in the running state is called a system link if they only ensure the system works. The length of a bivalent system is equal to the minimum number of elements that the system holds. In this paper we present an algorithm for the automatic determination of the length of a bivalent system, a Matlab script, a case study and subsequent development directions

scholarly journals Installed Performance Assessment of an Array of Distributed Propulsors Ingesting Boundary Layer Flow

2017 ◽  
Author(s):  
Chana Goldberg ◽  
Devaiah Nalianda ◽  
Pericles Pilidis
Keyword(s):  
Boundary Layer ◽  
Fuel Consumption ◽  
Propulsion System ◽  
Accounting System ◽  
Local Flow ◽  
System A ◽  
Maximum Payload ◽  
Aircraft Performance ◽  
Layer Flow

Conventional propulsion systems are typically represented as uninstalled system to suit the simple separation between airframe and engine in a podded configuration. However, boundary layer ingesting systems are inherently integrated, and require a different perspective for performance analysis. Simulations of boundary layer ingesting propulsions systems must represent the change in inlet flow characteristic which result from the local flow condition. In addition, a suitable accounting system is required to split the airframe forces from the propulsion system forces. The research assesses the performance of a conceptual vehicle which applies a boundary layer ingesting propulsion system — NASA’s N3-X blended wing body aircraft — as a case study. The performance of the aircraft’s distributed propulsor array is assessed using a performance method which accounts for installation terms resulting from the boundary layer ingesting nature of the system. A ‘thrust split’ option is considered which splits the source of thrust between the aircraft’s main turbojet engines and the distributed propulsor array. An optimum thrust split for a specific fuel consumption at cruise is found to occur for a thrust split value of 93%, for the configuration considered. In comparison, the optimum thrust split with respect to fuel consumption for the design 7500 nmi mission is found to be 91.5%. Aircraft performance estimates suggest the N3-X could achieve a maximum payload range of approximately 13650 nautical miles.

scholarly journals Investigation of ship electric propulsion system performance from environmental and energy efficiency perspective

2021 ◽  
Author(s):  
Ahmed G. Elkafas ◽  
Mohamed R. Shouman
Keyword(s):  
Energy Efficiency ◽  
Electric Propulsion ◽  
Phase 1 ◽  
Propulsion System ◽  
Point Of View ◽  
Emission Rates ◽  
Maritime Industry ◽  
Baseline Phase ◽  
Electric Propulsion System

Abstract The maritime industry faces many challenges regarding the adverse environmental impact, whether at the level of legislation set by the International Maritime Organization (IMO) or the economic crises that arising from the Covid-19 pandemic. IMO has found that the highest percentage of ship emission is mainly coming from the ship propulsion systems. Therefore, the current research proposes an electric propulsion system to drive the ship instead of the conventional one to reduce ship emissions and enhance energy efficiency. As a case study, a passenger ship is investigated. The results showed that the proposed electric propulsion system has lower emission rates than the conventional one by 10%, 21%, and 88% for CO2, NOx, and SOx emission, respectively. From an energy efficiency point of view, the diesel-electric propulsion system enhances the energy efficiency and complies with the required IMO values as actual energy efficiency is about 66%, 70%, 83%, and 95% of the required IMO values at baseline, phase 1, phase 2 and phase 3, respectively.

scholarly journals VR Education Support System—A Case Study of Digital Circuits Design

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 277
Author(s):  
Andrzej Paszkiewicz ◽  
Mateusz Salach ◽  
Dominik Strzałka ◽  
Grzegorz Budzik ◽  
Alicja Nikodem ◽  
...  
Keyword(s):  
Digital Circuits ◽  
Computer Game ◽  
Point Of View ◽  
Knowledge And Skills ◽  
Staff Members ◽  
System A ◽  
Education Support ◽  
High Level ◽  
Significant Factors

Areas of experience allow for the acquisition and consolidation of both existing knowledge and skills. These are significant factors in the training of staff members for companies in the Industry 4.0 area. One of the currently available modern tools used in the teaching process is virtual reality (VR) technology. This technology, due to its high level of immersion and involvement of the different senses, and the need to focus on the performed activities, allows one to develop skills in solving various tasks and problems. The extended VR environment enables the creation of diverse teaching scenarios adapted to the needs of industry. This paper presents the possibility of building training scenarios in the field of digital techniques. The software solution, developed and presented by the authors, uses elements of computer game mechanics and is designed to familiarize students with the idea of digital circuits, their construction, logical implementation and application. This paper also presents a comparison of the features of different forms of education used in teaching digital techniques, as well as a comparison of these forms, from the point of view of the student and his/her perceptions.

High-resolution electron microscopy of Cu2O surfaces

1986 ◽  
Vol 44 ◽  
pp. 396-397
Author(s):  
V. Castano ◽  
W. Krakow
Keyword(s):  
High Resolution ◽  
Natural Extension ◽  
High Resolution Electron Microscopy ◽  
Point Of View ◽  
Initial Oxidation ◽  
System A ◽  
Resolution Electron ◽  
Surface Reconstructions ◽  
Atomic Surface ◽  
Au Thin Films

In non-UHV microscope environments atomic surface structure has been observed for flat-on for various orientations of Au thin films and edge-on for columns of atoms in small particles. The problem of oxidation of surfaces has only recently been reported from the point of view of high resolution microscopy revealing surface reconstructions for the Ag2O system. A natural extension of these initial oxidation studies is to explore other materials areas which are technologically more significant such as that of Cu2O, which will now be described.

Technology and Hospital Information System: A Case of Implementation of Electronic Clinical Records in Hospital Maternity Irene Neto in Lubango, Angola

2019 ◽  
Vol 10 (11) ◽  
pp. 1131-1135
Author(s):  
Tomas Hambili Paulo Sanjuluca ◽  
◽  
Ricardo Correia ◽  
Anabela Antunes de Almeida ◽  
Ana Gloria Diaz Martinez ◽  
...  
Keyword(s):  
Maternity Hospital ◽  
Management Support ◽  
Retrospective Case ◽  
System A ◽  
Clinical Records ◽  
Retrospective Case Study ◽  
The Impact ◽  
And Child Health

Introduction: In order to have a good assessment of the quality of maternal and child health care, it is essential that there is up-to-date and reliable information. Objective: To evaluate the impact of the implementation of a computerized database of clinical processes in the admission, archive and medical statistics section, of Maternity hospital Irene Neto/Lubango-Angola. Methodology: A descriptive study with a quantitative and qualitative approach to carry out a retrospective case study deliveries and newborns, records from 2014 to 2017. Final considerations: The implementation of this project may contribute to the improvement of clinical management support management of the hospital as well as facilitating access to information for research and scientific production.

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