scholarly journals Influence of deviations in manufacturing of electrothermal propulsion system on nanosatellite maneuvering accuracy

2021 ◽  
Vol 20 (1) ◽  
pp. 29-45
Author(s):  
L. I. Sinitsin ◽  
I. V. Belokonov
Keyword(s):  
Statistical Models ◽  
Propulsion System ◽  
Design Parameters ◽  
Spacecraft Motion ◽  
Case Scenario ◽  
Propulsion Systems ◽  
Worst Case ◽  
Growth Vector ◽  
Common Causes ◽  
Electrothermal Propulsion

A method is proposed for assessing the results of adjustment maneuvers for a nanosatellite (NS) with an electrothermal propulsion system (ETPS). Using the example of the SamSat-M nanosatellite under development, common causes of maneuvering errors associated with deviations in the manufacturing of the propulsion system are revealed. Probabalistic analysis of the NS maneuvering process was carried out. The design parameters of the ETPS are considered as random factors. Statistical models of the distributions of all random factors are assumed to be equally probable, which is the worst-case scenario, since the true distributions of the design parameters of the ETPS are unknown. The methodological basis of the study is the method of statistical modeling (Monte Carlo method) followed by the use of regression and factor analysis, on the basis of which the influence of the scatter of each of the design parameters on the controlled parameters is determined. Requirements for the design parameters of the ETPS that affect the spread of the projections of the velocity growth vector of the NS and the arising angular motion have been formulated. The presented results can be used to assess the influence of production deviations in the design parameters of propulsion systems on the nature of spacecraft motion, as well as to state requirements for the spread of design parameters to ensure the achievement of the objective.

Inlet Duct-Engine Exhaust Nozzle Airflow Matching for the Supersonic Transport

1968 ◽  
Vol 72 (690) ◽  
pp. 490-497
Author(s):  
J. B. Taylor
Keyword(s):  
Propulsion System ◽  
Operating Conditions ◽  
Design Parameters ◽  
Gas Generator ◽  
Propulsion Systems ◽  
Engine Exhaust ◽  
Supersonic Transport ◽  
Reliable Performance ◽  
Jet Nozzle ◽  
Secondary Air

Propulsion systems selected for commercial transports must provide efficient and reliable performance over a broad range of conditions. These aeroplanes are used over both short and long route segments, on non-standard days, and at a range of altitudes to meet air-line schedule requirements. This paper covers some of the design parameters that were considered in the integration of the induction system, secondary air system, jet nozzle and the basic turbojet gas generator for the SST. During recent years some of the most important gains in propulsion efficiency have resulted from the development of inlets, engines and exhaust nozzles which are matched over a broad range of operating conditions. An efficient propulsion system for a supersonic transport depends upon very close matching of these components. This, of course, requires a better understanding of the capabilities and limitations of each of these major components. For the supersonic transport, 50% or more of the gross weight will be comprised of propulsion system and fuel and less than 10% will be payload.

Defining the Ecological Coefficient of Performance for an Aircraft Propulsion System

2018 ◽  
Vol 35 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Yasin Şöhret
Keyword(s):  
Performance Indicator ◽  
Propulsion System ◽  
Coefficient Of Performance ◽  
Design Parameters ◽  
Propulsion Systems ◽  
Turbojet Engine ◽  
Energy Conversion Systems ◽  
And Performance ◽  
Aircraft Propulsion System ◽  
Aircraft Propulsion

Abstract The aircraft industry, along with other industries, is considered responsible these days regarding environmental issues. Therefore, the performance evaluation of aircraft propulsion systems should be conducted with respect to environmental and ecological considerations. The current paper aims to present the ecological coefficient of performance calculation methodology for aircraft propulsion systems. The ecological coefficient performance is a widely-preferred performance indicator of numerous energy conversion systems. On the basis of thermodynamic laws, the methodology used to determine the ecological coefficient of performance for an aircraft propulsion system is parametrically explained and illustrated in this paper for the first time. For a better understanding, to begin with, the exergy analysis of a turbojet engine is described in detail. Following this, the outputs of the analysis are employed to define the ecological coefficient of performance for a turbojet engine. At the end of the study, the ecological coefficient of performance is evaluated parametrically and discussed depending on selected engine design parameters and performance measures. The author asserts the ecological coefficient of performance to be a beneficial indicator for researchers interested in aircraft propulsion system design and related topics.

scholarly journals Conceptual design and comparison of hybrid electric propulsion systems for small aircraft

2021 ◽  
Author(s):  
Jo Köhler ◽  
Peter Jeschke
Keyword(s):  
Conceptual Design ◽  
Electric Propulsion ◽  
Design Method ◽  
Propulsion System ◽  
Design Parameters ◽  
Propulsion Systems ◽  
Design Algorithm ◽  
Parallel Hybrid ◽  
Hybrid Electric ◽  
Small Aircraft

AbstractThis paper presents a novel conceptual design method for electric and hybrid electric propulsion systems in small aircraft. The effects of key design parameters on the propulsion system performance are analyzed and the advantages and drawbacks of the investigated propulsion systems are discussed on the basis of two sets of thrust requirements. First, the general conceptual design algorithm is outlined. This is followed by a description of the three propulsion systems investigated: the fully electric; the parallel hybrid; and the conventional internal combustion engine. Scalable models of all required propulsion system components are presented, including weight estimation and operating characteristics. Afterwards, the conceptual design algorithm is exemplified for a reference two-seater motorized glider with a cruising speed of 140 kt and a maximum take-off mass of 1000 kg. Key design parameters are identified and their impact on propulsion system mass and cruise efficiency discussed. This study suggests that the parallel hybrid propulsion system is advantageous for high power ratios between take-off and cruise. For a power ratio of 4.5, either a relative cruise efficiency advantage of 12% or a maximum system mass advantage of 10% can be expected, depending on the propeller design. For the chosen cruise range of 300 km, the system mass of the fully electric propulsion system is at least 2.37 times higher when compared to the conventional propulsion system. In summary, a design method for hybrid electric propulsion systems is presented here which may be used for conceptual design. Furthermore, the suitability of the propulsion systems under investigation for different sets of thrust requirements is assessed, which may be helpful for aircraft designers.

scholarly journals Low-thrust liquid-propellant rocket engines as part of advanced ultralight rocket vehicle systems

2021 ◽  
Vol 5 (1) ◽  
pp. 5-13
Author(s):  
T. A. Basharina ◽  
M. G. Goncharov ◽  
S. N. Lymich ◽  
V. S. Levin ◽  
D. P. Shmatov
Keyword(s):  
Additive Technologies ◽  
Propulsion System ◽  
Design Parameters ◽  
Rocket Engines ◽  
Operating Pressure ◽  
Low Thrust ◽  
Combustion Chambers ◽  
Propulsion Systems ◽  
Energy Characteristics ◽  
Design Solutions

This work examines the most promising design solutions for the creation of propulsion systems for ultra-light launch vehicles by small private enterprises in the rocket and space industry. Comparison of the metal consumption of the combustion chambers with the energy characteristics at different operating pressures showed that the most optimal operating pressure is 12,16 MPa. Comparison of the relative and absolute values of the masses of various configurations describes the nature of the relationship between the number of combustion chambers and the total mass of the propulsion system. It was found that nine-chamber propulsion systems with cameras made with extensive use of additive technologies best meet the key requirements. The analysis carried out includes an assessment of the design parameters of both various components and assemblies and the propulsion system as a whole. Various layouts of propulsion systems are considered in detail, the required degree of technological complexity of structures of various units and assemblies, their production cost are estimated. The ratio of the obtained mass-energy characteristics was achieved through the implementation of design solutions that became available due to the use of additive technologies. The obtained results of preliminary calculations demonstrate the applicability and efficiency of design solutions considered for use in the propelled propulsion system for a promising launch vehicle.

Reducing Probabilistic Weather Forecasts to the Worst Case Scenario: Anchoring Effects

2008 ◽  
Author(s):  
Sonia Savelli ◽  
Susan Joslyn ◽  
Limor Nadav-Greenberg ◽  
Queena Chen
Keyword(s):  
Case Scenario ◽  
Worst Case ◽  
Weather Forecasts ◽  
Worst Case Scenario ◽  
Anchoring Effects

EXPEDITION TO MALI, 2020

2020 ◽  
pp. 12-28
Author(s):  
D. V. Vaniukova ◽  
◽  
P. A. Kutsenkov ◽  
Keyword(s):  
Mass Murder ◽  
The State ◽  
Case Scenario ◽  
Worst Case ◽  
Traditional Art ◽  
Peter The Great ◽  
State Museum ◽  
Bobo Dioulasso ◽  
Oriental Studies ◽  
The Village

The research expedition of the Institute of Oriental studies of the Russian Academy of Sciences has been working in Mali since 2015. Since 2017, it has been attended by employees of the State Museum of the East. The task of the expedition is to study the transformation of traditional Dogon culture in the context of globalization, as well as to collect ethnographic information (life, customs, features of the traditional social and political structure); to collect oral historical legends; to study the history, existence, and transformation of artistic tradition in the villages of the Dogon Country in modern conditions; collecting items of Ethnography and art to add to the collection of the African collection of the. Peter the Great Museum (Kunstkamera, Saint Petersburg) and the State Museum of Oriental Arts (Moscow). The plan of the expedition in January 2020 included additional items, namely, the study of the functioning of the antique market in Mali (the “path” of things from villages to cities, which is important for attributing works of traditional art). The geography of our research was significantly expanded to the regions of Sikasso and Koulikoro in Mali, as well as to the city of Bobo-Dioulasso and its surroundings in Burkina Faso, which is related to the study of migrations to the Bandiagara Highlands. In addition, the plan of the expedition included organization of a photo exhibition in the Museum of the village of Endé and some educational projects. Unfortunately, after the mass murder in March 2019 in the village of Ogossogou-Pel, where more than one hundred and seventy people were killed, events in the Dogon Country began to develop in the worst-case scenario: The incessant provocations after that revived the old feud between the Pel (Fulbe) pastoralists and the Dogon farmers. So far, this hostility and mutual distrust has not yet developed into a full-scale ethnic conflict, but, unfortunately, such a development now seems quite likely.

Risk-Based Robust Bidding Strategies for EVs’ Aggregators in Day-ahead Markets with Uncertainty

2020 ◽  
Author(s):  
Ahmed Abdelmoaty ◽  
Wessam Mesbah ◽  
Mohammad A. M. Abdel-Aal ◽  
Ali T. Alawami
Keyword(s):  
Robust Optimization ◽  
Electricity Market ◽  
Real Life ◽  
Optimization Approach ◽  
Case Scenario ◽  
Worst Case ◽  
Bidding Strategies ◽  
Wind Generators ◽  
Proposed Model ◽  
Optimal Bidding

In the recent electricity market framework, the profit of the generation companies depends on the decision of the operator on the schedule of its units, the energy price, and the optimal bidding strategies. Due to the expanded integration of uncertain renewable generators which is highly intermittent such as wind plants, the coordination with other facilities to mitigate the risks of imbalances is mandatory. Accordingly, coordination of wind generators with the evolutionary Electric Vehicles (EVs) is expected to boost the performance of the grid. In this paper, we propose a robust optimization approach for the coordination between the wind-thermal generators and the EVs in a virtual<br>power plant (VPP) environment. The objective of maximizing the profit of the VPP Operator (VPPO) is studied. The optimal bidding strategy of the VPPO in the day-ahead market under uncertainties of wind power, energy<br>prices, imbalance prices, and demand is obtained for the worst case scenario. A case study is conducted to assess the e?effectiveness of the proposed model in terms of the VPPO's profit. A comparison between the proposed model and the scenario-based optimization was introduced. Our results confirmed that, although the conservative behavior of the worst-case robust optimization model, it helps the decision maker from the fluctuations of the uncertain parameters involved in the production and bidding processes. In addition, robust optimization is a more tractable problem and does not suffer from<br>the high computation burden associated with scenario-based stochastic programming. This makes it more practical for real-life scenarios.<br>

scholarly journals A Thermally Conductive Pt/AAO Catalyst for Hydrogen Passive Autocatalytic Recombination

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 491
Author(s):  
Alina E. Kozhukhova ◽  
Stephanus P. du Preez ◽  
Aleksander A. Malakhov ◽  
Dmitri G. Bessarabov
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Combustion Temperature ◽  
Volume Fraction ◽  
Morphological Characteristics ◽  
Al Alloy ◽  
Impregnation Method ◽  
Case Scenario ◽  
Worst Case ◽  
Thermal Distribution

In this study, a Pt/anodized aluminum oxide (AAO) catalyst was prepared by the anodization of an Al alloy (Al6082, 97.5% Al), followed by the incorporation of Pt via an incipient wet impregnation method. Then, the Pt/AAO catalyst was evaluated for autocatalytic hydrogen recombination. The Pt/AAO catalyst’s morphological characteristics were determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average Pt particle size was determined to be 3.0 ± 0.6 nm. This Pt/AAO catalyst was tested for the combustion of lean hydrogen (0.5–4 vol% H2 in the air) in a recombiner section testing station. The thermal distribution throughout the catalytic surface was investigated at 3 vol% hydrogen (H2) using an infrared camera. The Al/AAO system had a high thermal conductivity, which prevents the formation of hotspots (areas where localized surface temperature is higher than an average temperature across the entire catalyst surface). In turn, the Pt stability was enhanced during catalytic hydrogen combustion (CHC). A temperature gradient over 70 mm of the Pt/AAO catalyst was 23 °C and 42 °C for catalysts with uniform and nonuniform (worst-case scenario) Pt distributions. The commercial computational fluid dynamics (CFD) code STAR-CCM+ was used to compare the experimentally observed and numerically simulated thermal distribution of the Pt/AAO catalyst. The effect of the initial H2 volume fraction on the combustion temperature and conversion of H2 was investigated. The activation energy for CHC on the Pt/AAO catalyst was 19.2 kJ/mol. Prolonged CHC was performed to assess the durability (reactive metal stability and catalytic activity) of the Pt/AAO catalyst. A stable combustion temperature of 162.8 ± 8.0 °C was maintained over 530 h of CHC. To confirm that Pt aggregation was avoided, the Pt particle size and distribution were determined by TEM before and after prolonged CHC.

scholarly journals Multi-Objective Optimisation of Tyre and Suspension Parameters during Cornering for Different Road Roughness Profiles

2021 ◽  
Vol 11 (13) ◽  
pp. 5934
Author(s):  
Georgios Papaioannou ◽  
Jenny Jerrelind ◽  
Lars Drugge
Keyword(s):  
Optimal Solution ◽  
Design Parameters ◽  
Road Vehicles ◽  
Propulsion Systems ◽  
Vehicle Handling ◽  
Optimum Parameters ◽  
Trade Offs ◽  
Road Roughness ◽  
Control Technologies ◽  
Tyre Wear

Effective emission control technologies and novel propulsion systems have been developed for road vehicles, decreasing exhaust particle emissions. However, work has to be done on non-exhaust traffic related sources such as tyre–road interaction and tyre wear. Given that both are inevitable in road vehicles, efforts for assessing and minimising tyre wear should be considered. The amount of tyre wear is because of internal (tyre structure, manufacturing, etc.) and external (suspension configuration, speed, road surface, etc.) factors. In this work, the emphasis is on the optimisation of such parameters for minimising tyre wear, but also enhancing occupant’s comfort and improving vehicle handling. In addition to the search for the optimum parameters, the optimisation is also used as a tool to identify and highlight potential trade-offs between the objectives and the various design parameters. Hence, initially, the tyre design (based on some chosen tyre parameters) is optimised with regards to the above-mentioned objectives, for a vehicle while cornering over both Class A and B road roughness profiles. Afterwards, an optimal solution is sought between the Pareto alternatives provided by the two road cases, in order for the tyre wear levels to be less affected under different road profiles. Therefore, it is required that the tyre parameters are as close possible and that they provide similar tyre wear in both road cases. Then, the identified tyre design is adopted and the optimum suspension design is sought for the two road cases for both passive and semi-active suspension types. From the results, significant conclusions regarding how tyre wear behaves with regards to passenger comfort and vehicle handling are extracted, while the results illustrate where the optimum suspension and tyre parameters have converged trying to compromise among the above objectives under different road types and how suspension types, passive and semi-active, could compromise among all of them more optimally.

scholarly journals A Comparison of Match Demands Using Ball-in-Play versus Whole Match Data in Professional Soccer Players of the English Championship

Sports ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 76
Author(s):  
Dylan Mernagh ◽  
Anthony Weldon ◽  
Josh Wass ◽  
John Phillips ◽  
Nimai Parmar ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Soccer Players ◽  
Training Methods ◽  
Case Scenario ◽  
Worst Case ◽  
Repeated Measures Design ◽  
Worst Case Scenario ◽  
Professional Soccer ◽  
Peak Match ◽  
Playing Time

This is the first study to report the whole match, ball-in-play (BiP), ball-out-of-play (BoP), and Max BiP (worst case scenario phases of play) demands of professional soccer players competing in the English Championship. Effective playing time per soccer game is typically <60 min. When the ball is out of play, players spend time repositioning themselves, which is likely less physically demanding. Consequently, reporting whole match demands may under-report the physical requirements of soccer players. Twenty professional soccer players, categorized by position (defenders, midfielders, and forwards), participated in this study. A repeated measures design was used to collect Global Positioning System (GPS) data over eight professional soccer matches in the English Championship. Data were divided into whole match and BiP data, and BiP data were further sub-divided into different time points (30–60 s, 60–90 s, and >90 s), providing peak match demands. Whole match demands recorded were compared to BiP and Max BiP, with BiP data excluding all match stoppages, providing a more precise analysis of match demands. Whole match metrics were significantly lower than BiP metrics (p < 0.05), and Max BiP for 30–60 s was significantly higher than periods between 60–90 s and >90 s. No significant differences were found between positions. BiP analysis allows for a more accurate representation of the game and physical demands imposed on professional soccer players. Through having a clearer understanding of maximum game demands in professional soccer, practitioners can design more specific training methods to better prepare players for worst case scenario passages of play.

Sign in / Sign up

Export Citation Format

Share Document