cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.6832706
title: Ground-Based Microwave Radiometer Calibration: an Overview

description: ABSTRACT This paper intends to briefly present some basic concepts on the microwave radiometry and radiometer calibration research in remote sensing applications and demonstrate results and analysis of the cryogenic calibration of a microwave ground-based radiometer currently deployed in scientific campaigns in Brazil. The equipment described in this text operates at 22 - 30 GHz and at 51 - 59 GHz frequency ranges and uses as the calibration standard a target cooled by liquid nitrogen. Since an accurate calibration (with observation errors below 0.5 K) is important to provide confidence in the retrieval of vertical temperature and humidity profiles, this work aims also to comment on some effects of the errors in calibration procedure on the atmospheric parameters of interest.
DOI: 10.6084/m9.figshare.6832706.v1
title: Ground-Based Microwave Radiometer Calibration: an Overview

description: ABSTRACT This paper intends to briefly present some basic concepts on the microwave radiometry and radiometer calibration research in remote sensing applications and demonstrate results and analysis of the cryogenic calibration of a microwave ground-based radiometer currently deployed in scientific campaigns in Brazil. The equipment described in this text operates at 22 - 30 GHz and at 51 - 59 GHz frequency ranges and uses as the calibration standard a target cooled by liquid nitrogen. Since an accurate calibration (with observation errors below 0.5 K) is important to provide confidence in the retrieval of vertical temperature and humidity profiles, this work aims also to comment on some effects of the errors in calibration procedure on the atmospheric parameters of interest.
DOI: 10.6084/m9.figshare.5792808
title: Susceptibility of GPS-Dependent Complex Systems to Spoofing

description: ABSTRACT GPS-based systems have been widely used in different critical sectors, including civilian and military applications. Despite of being able to provide great benefits, under certain circumstances they show to be highly vulnerable to intentional interferences. In this context, this article aimed to evaluate the susceptibility of different complex GPS-dependent systems to intentional interferences, focusing on the technique known as spoofing. This technique presents a high complexity and a great potential for damaging/deceiving complex systems, besides being difficult to identify and to implement countermeasures. Complex systems, like mobile phones, automobile receivers and aircraft receivers were submitted to different levels of spoofing, in free space and in a semi-anechoic chamber, being corrupted with low power levels of interference.
DOI: 10.6084/m9.figshare.5792808.v1
title: Susceptibility of GPS-Dependent Complex Systems to Spoofing

description: ABSTRACT GPS-based systems have been widely used in different critical sectors, including civilian and military applications. Despite of being able to provide great benefits, under certain circumstances they show to be highly vulnerable to intentional interferences. In this context, this article aimed to evaluate the susceptibility of different complex GPS-dependent systems to intentional interferences, focusing on the technique known as spoofing. This technique presents a high complexity and a great potential for damaging/deceiving complex systems, besides being difficult to identify and to implement countermeasures. Complex systems, like mobile phones, automobile receivers and aircraft receivers were submitted to different levels of spoofing, in free space and in a semi-anechoic chamber, being corrupted with low power levels of interference.
DOI: 10.6084/m9.figshare.7304672
title: American Space Nuclear Electric Systems

description: ABSTRACT: Since the 1960's the United States of America has launched several space missions using nuclear technology as a mean for propulsion and power supply. The majority of the American nuclear powered spacecrafts were based in radioisotope generators, with the exception of the SNAP-10A (1965), which was the only American reactor ever launched. However, some of the most notorious nuclear reactor based projects developed in the USA in the last four decades were the SPAR/SP-100 (an evolution of the Space Power Advanced Reactor program), the Space Prototype (SP-100), the Prometheus, and the Fission Surface Power (FSP). The latter is still in progress and the others were closed before its completion. This paper describes the main details about each one of these projects with the purpose of serving as a review of the technical history for the major realization steps that were conducted in the USA. This manuscript also approaches the contemporary state-of-the-art, with emphasis to the Demonstration Using Flattop Fission (DUFF) experiment and it's follow-on project, the Kilopower prototype reactor.
DOI: 10.6084/m9.figshare.7304672.v1
title: American Space Nuclear Electric Systems

description: ABSTRACT: Since the 1960's the United States of America has launched several space missions using nuclear technology as a mean for propulsion and power supply. The majority of the American nuclear powered spacecrafts were based in radioisotope generators, with the exception of the SNAP-10A (1965), which was the only American reactor ever launched. However, some of the most notorious nuclear reactor based projects developed in the USA in the last four decades were the SPAR/SP-100 (an evolution of the Space Power Advanced Reactor program), the Space Prototype (SP-100), the Prometheus, and the Fission Surface Power (FSP). The latter is still in progress and the others were closed before its completion. This paper describes the main details about each one of these projects with the purpose of serving as a review of the technical history for the major realization steps that were conducted in the USA. This manuscript also approaches the contemporary state-of-the-art, with emphasis to the Demonstration Using Flattop Fission (DUFF) experiment and it's follow-on project, the Kilopower prototype reactor.
DOI: 10.6084/m9.figshare.7511219
title: Application of a Bibliometric Tool for Studying Space Technology Trends

description: ABSTRACT: The statistical analysis of academic literature, also known as “bibliometrics”, is being increasingly applied to analyse research trends, to identify emerging areas of science and to find out where and how often specific articles are cited. The aim of this study was to identify technological innovation trend patterns in the aerospace sector applying bibliometric analysis over the period 2008 - 2015. In this study the keywords space technology, satellite, space launch vehicle, spacecraft, rocket and space station were used to scrutinize the database Web of Science (ISI). The obtained records were analysed using the Patent Insight Pro software (2015). It was observed that the researches related to aerospace technological development has been focused in satellites, giving also some directions for satellite launch vehicles. Bibliometric analysis revealed concern on new low-cost technologies development, and the applied logistic fit suggests that over the next five years the continuity on new space technologies development will be mostly related to small satellites, with also contributions associated with high-resolution imagery in order to improve Earth observation in low orbit.
DOI: 10.6084/m9.figshare.7511219.v1
title: Application of a Bibliometric Tool for Studying Space Technology Trends

description: ABSTRACT: The statistical analysis of academic literature, also known as “bibliometrics”, is being increasingly applied to analyse research trends, to identify emerging areas of science and to find out where and how often specific articles are cited. The aim of this study was to identify technological innovation trend patterns in the aerospace sector applying bibliometric analysis over the period 2008 - 2015. In this study the keywords space technology, satellite, space launch vehicle, spacecraft, rocket and space station were used to scrutinize the database Web of Science (ISI). The obtained records were analysed using the Patent Insight Pro software (2015). It was observed that the researches related to aerospace technological development has been focused in satellites, giving also some directions for satellite launch vehicles. Bibliometric analysis revealed concern on new low-cost technologies development, and the applied logistic fit suggests that over the next five years the continuity on new space technologies development will be mostly related to small satellites, with also contributions associated with high-resolution imagery in order to improve Earth observation in low orbit.
DOI: 10.6084/m9.figshare.5931697
title: An Innovative Structural Fatigue Monitoring Solution for General Aviation Aircraft

description: ABSTRACT: This article proposes a novel and effective solution for estimating fatigue life of General Aviation (GA) airframes using flight data produced by digital avionics systems, which are being installed or retrofitted into a growing number of GA aircraft. In the proposed implementation, a flight dynamics model is adopted to process the recorded flight data and to determine the dynamic loadings experienced by the aircraft. The equivalent loading cycles at fatigue-critical points of the primary structure are counted by means of statistical methods. For validation purposes, the developed approach is applied to flight data recorded by a fleet of Cessna 172S aircraft fitted with a Garmin G1000 integrated navigation and guidance system. Based on the initial experimental results and the developed uncertainty analysis, the proposed approach provides acceptable estimates of the residual fatigue life of the aircraft, thereby allowing a cost-effective and streamlined structural integrity monitoring solution. Future developments will address the possible adoption of the proposed method for unmanned aircraft structural health monitoring, also considering the accuracy enhancements achievable with advanced navigation and guidance architectures based on Global Navigation Satellite Systems (GNSS), Vision-Based Navigation (VBN) Sensors, Inertial Measurement Units (IMU) and Aircraft Dynamics Model (ADM) augmentation.
DOI: 10.6084/m9.figshare.7509083
title: One-Dimensional Thermal Analysis Model for Charring Ablative Materials

description: ABSTRACT: This paper presents a one-dimensional model for the analysis of the charring ablative materials used in spacecraft thermal protection systems. The numerical method is based on an implicit finite difference formulation of the governing equations written for a system of mobile coordinates that accounts for the possible presence of surface recession. The maximum allowable operating temperature for the adhesive layer of the junction between the heat shield and the substructure is used as a design parameter for determining the minimum heat shield thickness. A case study on the re-entry of the Stardust capsule is presented. The model proposed as a useful dimensioning tool for the preliminary design phase of the heat shields of spacecraft entering the atmosphere. The model was validated through a survey of the literature related to the dimensioning of thermal shields, but based on numeric programs of highly representative industrial standards.
DOI: 10.6084/m9.figshare.7509083.v1
title: One-Dimensional Thermal Analysis Model for Charring Ablative Materials

description: ABSTRACT: This paper presents a one-dimensional model for the analysis of the charring ablative materials used in spacecraft thermal protection systems. The numerical method is based on an implicit finite difference formulation of the governing equations written for a system of mobile coordinates that accounts for the possible presence of surface recession. The maximum allowable operating temperature for the adhesive layer of the junction between the heat shield and the substructure is used as a design parameter for determining the minimum heat shield thickness. A case study on the re-entry of the Stardust capsule is presented. The model proposed as a useful dimensioning tool for the preliminary design phase of the heat shields of spacecraft entering the atmosphere. The model was validated through a survey of the literature related to the dimensioning of thermal shields, but based on numeric programs of highly representative industrial standards.
DOI: 10.6084/m9.figshare.5931613
title: GPS Jamming Signals Propagation in Free-Space, Urban and Suburban Environments

description: ABSTRACT: GPS-based systems have been widely used in different critical sectors, including civilian, military and commercial applications. Despite of being able to provide great benefits, under certain circumstances they show to be highly vulnerable to intentional interferences. In this context, this article aimed to evaluate the vulnerability range of this kind of systems, focusing on different kinds of environments and based on different propagation models, to which the simulations were performed. Results show high vulnerabilities of GPS-based systems even when operating in a well-protected urban environment, in a short range and under low-power sources of radiation. Graphs are presented with the range of effectiveness for different power levels of jammer in different situations. Evaluations are performed not only for the acquisition but also for the tracking processes of the GPS receivers, therefore being possible to establish a safe operation range for having a trustful GPS signal and mitigate malicious actions. The comparisons allow, as well, highlighting the importance of using the correct propagation model, in order to achieve consistent results, depending on the desired situation.
DOI: 10.6084/m9.figshare.5931613.v1
title: GPS Jamming Signals Propagation in Free-Space, Urban and Suburban Environments

description: ABSTRACT: GPS-based systems have been widely used in different critical sectors, including civilian, military and commercial applications. Despite of being able to provide great benefits, under certain circumstances they show to be highly vulnerable to intentional interferences. In this context, this article aimed to evaluate the vulnerability range of this kind of systems, focusing on different kinds of environments and based on different propagation models, to which the simulations were performed. Results show high vulnerabilities of GPS-based systems even when operating in a well-protected urban environment, in a short range and under low-power sources of radiation. Graphs are presented with the range of effectiveness for different power levels of jammer in different situations. Evaluations are performed not only for the acquisition but also for the tracking processes of the GPS receivers, therefore being possible to establish a safe operation range for having a trustful GPS signal and mitigate malicious actions. The comparisons allow, as well, highlighting the importance of using the correct propagation model, in order to achieve consistent results, depending on the desired situation.
DOI: 10.6084/m9.figshare.5931649
title: 3D Printing and its Effect on Outsourcing: A Study of the Indian Aircraft Industry

description: ABSTRACT: Indian Aircraft Industry has emerged as one of the rapid growing industrial endeavors in the world, with automation in most of its production and manufacturing areas. Technological advancements have led to this growth and, over the years, competitiveness has made the industry to efficiently look for avenues and other strategic alliances. In this direction, 3D printing technology has opened many opportunities. This study is focused on explaining the 3D printing technology utilization for production and servicing apart from developing a methodology to outsource various automated technologies to the tier-2/tier-3 companies basing themselves on specified parameters and capabilities by using the 3D printing. 3D printing in manufacturing industry, particularly in aircraft manufacture, has brought in novel prospective along with new challenges posturing new methodologies and innovative approaches to meet the global standards. In this line, the Indian Aircraft Industry has started redistributing its sourcing by outsourcing of certain non-strategic facilities and parts that can be manufactured with the use of 3D printing/additive manufacturing, computerization and automation to outsiders, aiming at development of capabilities in the partnership industry, to provide the scope for generating high volume at the affiliated industries to pave way for a win-win ground. Already playing a good role in aircraft engine manufacture at Indian aircraft industry, 3D printing is going to play a more vital role in the total aircraft manufacture and avionics in the next few years, if the present scenario is pragmatic in line with the industrial needs. With the advantage of "low or zero" waste, less impact on environment, apart from possibility of local manufacture and just-in-time delivery, with greater specification of the final product, outsourcing of the parts and products for the entire aircraft manufacture will be a reality as per the current research, thriving on improved production volumes of similar parts for various end users. Research further suggests that outsourcing configuration is looking to invest in the new methods and "timely production" would become an assurance with 3D printing.
DOI: 10.6084/m9.figshare.5931649.v1
title: 3D Printing and its Effect on Outsourcing: A Study of the Indian Aircraft Industry

description: ABSTRACT: Indian Aircraft Industry has emerged as one of the rapid growing industrial endeavors in the world, with automation in most of its production and manufacturing areas. Technological advancements have led to this growth and, over the years, competitiveness has made the industry to efficiently look for avenues and other strategic alliances. In this direction, 3D printing technology has opened many opportunities. This study is focused on explaining the 3D printing technology utilization for production and servicing apart from developing a methodology to outsource various automated technologies to the tier-2/tier-3 companies basing themselves on specified parameters and capabilities by using the 3D printing. 3D printing in manufacturing industry, particularly in aircraft manufacture, has brought in novel prospective along with new challenges posturing new methodologies and innovative approaches to meet the global standards. In this line, the Indian Aircraft Industry has started redistributing its sourcing by outsourcing of certain non-strategic facilities and parts that can be manufactured with the use of 3D printing/additive manufacturing, computerization and automation to outsiders, aiming at development of capabilities in the partnership industry, to provide the scope for generating high volume at the affiliated industries to pave way for a win-win ground. Already playing a good role in aircraft engine manufacture at Indian aircraft industry, 3D printing is going to play a more vital role in the total aircraft manufacture and avionics in the next few years, if the present scenario is pragmatic in line with the industrial needs. With the advantage of "low or zero" waste, less impact on environment, apart from possibility of local manufacture and just-in-time delivery, with greater specification of the final product, outsourcing of the parts and products for the entire aircraft manufacture will be a reality as per the current research, thriving on improved production volumes of similar parts for various end users. Research further suggests that outsourcing configuration is looking to invest in the new methods and "timely production" would become an assurance with 3D printing.
DOI: 10.6084/m9.figshare.5980414
title: Dynamics of a Small Unmanned Aircraft Parachute System

description: ABSTRACT: Parachute Systems (PS) can be readily used by small Unmanned Aircraft Systems (UAS) for risk mitigation and aircraft recovery. To date there has been limited research into the fundamental dynamics of parachutes at low Reynolds numbers, with existing studies focusing on larger parachutes. An understanding of the dynamics is needed to establish sound guidelines for parachute design and for their use during UAS operations. Existing design guidelines are reviewed and the key parachute design parameters are identifi ed. The validity of the existing guidelines applied to lower Reynolds number parachutes is explored through a series of wind-tunnel tests. It was found that existing design guidelines underpredict the key parameters of infl ation time and peak forces for parachute deployments at typical UAS operating speeds. The ramifi cations on the design and operation of small UAS are discussed.
DOI: 10.6084/m9.figshare.5980414.v1
title: Dynamics of a Small Unmanned Aircraft Parachute System

description: ABSTRACT: Parachute Systems (PS) can be readily used by small Unmanned Aircraft Systems (UAS) for risk mitigation and aircraft recovery. To date there has been limited research into the fundamental dynamics of parachutes at low Reynolds numbers, with existing studies focusing on larger parachutes. An understanding of the dynamics is needed to establish sound guidelines for parachute design and for their use during UAS operations. Existing design guidelines are reviewed and the key parachute design parameters are identifi ed. The validity of the existing guidelines applied to lower Reynolds number parachutes is explored through a series of wind-tunnel tests. It was found that existing design guidelines underpredict the key parameters of infl ation time and peak forces for parachute deployments at typical UAS operating speeds. The ramifi cations on the design and operation of small UAS are discussed.
DOI: 10.6084/m9.figshare.6083492
title: Mode I+II Fatigue Crack Growth Delay by Stop-Holes

description: ABSTRACT: The technique of retarding the growth of fatigue cracks by drilling holes on the crack tip is well known. Most of the research works on this subject are limited to fatigue cracks subjected to mode I loading conditions. In the present work the fatigue crack growth retardation by stop-holes of cracks under mode I+II loading is investigated. The proposed approximate solution is based on the implementation of a mixed-mode fatigue crack growth model and a multiaxial high cycle fatigue criterion. Numerical results for mode I+II fatigue crack growth retardation on Al-2024 thin plate are derived and the effect of the crack inclination angle, as well as the diameter of the stop-hole, are discussed and commented.
DOI: 10.6084/m9.figshare.6083492.v1
title: Mode I+II Fatigue Crack Growth Delay by Stop-Holes

description: ABSTRACT: The technique of retarding the growth of fatigue cracks by drilling holes on the crack tip is well known. Most of the research works on this subject are limited to fatigue cracks subjected to mode I loading conditions. In the present work the fatigue crack growth retardation by stop-holes of cracks under mode I+II loading is investigated. The proposed approximate solution is based on the implementation of a mixed-mode fatigue crack growth model and a multiaxial high cycle fatigue criterion. Numerical results for mode I+II fatigue crack growth retardation on Al-2024 thin plate are derived and the effect of the crack inclination angle, as well as the diameter of the stop-hole, are discussed and commented.
DOI: 10.6084/m9.figshare.6007904
title: Run time Assessment for Gas Turbine Performance Simulation

description: ABSTRACT: This article describes the run time characteristics of a gas turbine performance simulation using different solvers and components off-design performance database formats. Two different nonlinear systems of equation solvers, Newton-Raphson's and Broyden's, and two different formats of compressor and turbine off-design performance database (maps), tabulated values and fitted surface equations, were compared. Based on the results it is then possible to trade off and select the most appropriate combination of solver and component map type for the gas turbine performance simulation for real-time application.