103 research outputs found
Towards Autonomous Aviation Operations: What Can We Learn from Other Areas of Automation?
Rapid advances in automation has disrupted and transformed several industries in the past 25 years. Automation has evolved from regulation and control of simple systems like controlling the temperature in a room to the autonomous control of complex systems involving network of systems. The reason for automation varies from industry to industry depending on the complexity and benefits resulting from increased levels of automation. Automation may be needed to either reduce costs or deal with hazardous environment or make real-time decisions without the availability of humans. Space autonomy, Internet, robotic vehicles, intelligent systems, wireless networks and power systems provide successful examples of various levels of automation. NASA is conducting research in autonomy and developing plans to increase the levels of automation in aviation operations. This paper provides a brief review of levels of automation, previous efforts to increase levels of automation in aviation operations and current level of automation in the various tasks involved in aviation operations. It develops a methodology to assess the research and development in modeling, sensing and actuation needed to advance the level of automation and the benefits associated with higher levels of automation. Section II describes provides an overview of automation and previous attempts at automation in aviation. Section III provides the role of automation and lessons learned in Space Autonomy. Section IV describes the success of automation in Intelligent Transportation Systems. Section V provides a comparison between the development of automation in other areas and the needs of aviation. Section VI provides an approach to achieve increased automation in aviation operations based on the progress in other areas. The final paper will provide a detailed analysis of the benefits of increased automation for the Traffic Flow Management (TFM) function in aviation operations
Unmanned Aircraft System (UAS) Traffic Management (UTM): Enabling Civilian Low-Altitude Airspace and Unmanned Aerial System Operations
Just a year ago we laid out the UTM challenges and NASA's proposed solutions. During the past year NASA's goal continues to be to conduct research, development and testing to identify airspace operations requirements to enable large-scale visual and beyond visual line-of-sight UAS operations in the low-altitude airspace. Significant progress has been made, and NASA is continuing to move forward
Safely Enabling Civilian Unmanned Aerial System (UAS) Operations in Low-Altitude Airspace by Unmanned Aerial System Traffic Management (UTM)
Many UAS will operate at lower altitude (Class G, below 2000 feet). There is an urgent need for a system for civilian low-altitude airspace and UAS operations. Stakeholders want to work with NASA to enable safe operations
Science, organization and the international agricultural research centers
This dissertation is an attempt to understand the relationship between scientific, social, ideological and organizational factors and the process of knowledge creation, evaluation, and diffusion of ideas in international agricultural research centers (IARCs). Data for the analysis came from 108 senior and middle level scientists working in two major IARCs;The dissertation follows the four article format. The first paper deals with the research problem selection. Several criteria of problem choice are examined, which include purely scientific, reward consideration and organizational priority. The results indicate that problem choice is more likely to be influenced by organizational consideration and societal problems than by reward considerations or by desire to extend certified knowledge;The second paper addresses the issue of work alienation. The analysis reveals that native scientists and younger scientists are more alienated. The results further indicate that decentralization of power coupled with higher formalization, healthy climate and supportive leadership behavior create lower work alienation;The third paper is devoted to understanding the effects of bureaucratization on organizational climate and leadership behavior. The results suggest that decentralization of power creates healthy climate and encourages supportive leadership. On the other hand a higher degree of formalization does not seem to be harmful for effective climate;The last paper focuses upon the publication productivity. The results reveal that older scientists are more productive than younger scientists. Those scientists who besides research spend some time in other activities such as teaching, administration, extension and consultation tend to write more publications. Also those who are basic research oriented publish more. A higher degree of participation in decision making coupled with a lower formalization tends to increase publication productivity of agricultural scientists
Next Gen Concepts and Technology Development Project Overview
Current Business Environment, National Airspace Systems Overview, Technical Challenge Overview and
Specifics
Seismic assessment of rc structures with infill masonry panels in Nepal: sensitivity analysis
Reinforced concrete (RC) buildings in Nepal are constructed as RC frames with masonry infill panels.
These structures exhibit a highly non-linear inelastic behaviour resulting from the interaction between
the masonry infill panels and the surrounding frames. In this context, the paper presents an extensive
case study of existing RC-framed buildings in a high seismic risk area in Nepal. A sensitivity analysis
of the structures with masonry infill is performed. For this, the influence of different material
properties is studied, namely diagonal compressive stress, modulus of elasticity and tensile stress of
masonry infill panels. Result shows the influence on the structural behaviour particularly by variation
of the diagonal compressive strength of infill masonry panels
Assessment of response reduction factor of RC buildings in Kathmandu Valley using non-linear pushover analysis
Master of Engineering in EarthquakeThis study addresses the issue of response reduction factor which is used in modern
codes to scale down the elastic response of the structure. The level of ductility and
overstrength of RC buildings in Kathmandu valley are investigated. The ductility and
overstrength factors are estimated by analyzing the buildings using non-linear pushover
analysis for 12 engineered designed RC buildings of various characteristics representing a
wide range of RC buildings in Kathmandu valley. Finally, the response reduction factor of RC
building in Kathmandu valley is evaluated by using the relation of ductility and overstrength
factor
Assessment of seismic strengthening solutions for existing low-rise RC buildings in Nepal
The main objective of this study is to analytically investigate the effectiveness of different strengthening solutions in upgrading the seismic performance of existing reinforced concrete (RC) buildings in Nepal. For this, four building models with different structural configurations and detailing were considered. Three possible rehabilitation solutions were studied, namely: (a) RC shear wall, (b) steel bracing, and (c) RC jacketing for all of the studied buildings. A numerical analysis was conducted with adaptive pushover and dynamic time history analysis. Seismic performance enhancement of the studied buildings was evaluated in terms of demand capacity ratio of the RC elements, capacity curve, inter-storey drift, energy dissipation capacity and moment curvature demand of the structures. Finally, the seismic safety assessment was performed based on standard drift limits, showing that retrofitting solutions significantly improved the seismic performance of existing buildings in Nepal
Seismic response of current RC buildings in Kathmandu Valley
RC buildings constitute the prevailing type of construction in earthquake-prone region like Kathmandu Valley. Most of these building constructions were based on conventional methods. In this context, the present paper studied the seismic behaviour of existing RC buildings in Kathmandu Valley. For this, four representative building structures with different design and construction, namely a building: (a) representing the non-engineered construction (RC1 and RC2) and (b) engineered construction (RC3 and RC4) has been selected for analysis. The dynamic properties of the case study building models are analyzed and the corresponding interaction with seismic action is studied by means of non-linear analyses. The structural response measures such as capacity curve, inter-storey drift and the effect of geometric non-linearities are evaluated for the two orthogonal directions. The effect of plan and vertical irregularity on the performance of the structures was studied by comparing the results of two engineered buildings. This was achieved through non-linear dynamic analysis with a synthetic earthquake subjected to X, Y and loading directions. The nature of the capacity curve represents the strong impact of the P-delta effect, leading to a reduction of the global lateral stiffness and reducing the strength of the structure. The non-engineered structures experience inter-storey drift demands higher than the engineered building models. Moreover, these buildings have very low lateral resistant, lesser the stiffness and limited ductility. Finally, a seismic safety assessment is performed based on the proposed drift limits. Result indicates that most of the existing buildings in Nepal exhibit inadequate seismic performance
Seismic safety assessment of existing masonry infill structures in Nepal
Reinforced concrete (RC) buildings in Nepal are constructed with RC frames and masonry infi ll panels. Thesestructures exhibit a highly non-linear inelastic behavior resulting from the interaction between the panels and frames. Thispaper presents an extensive case study of existing RC buildings in Nepal. Non-linear analyses were performed on structuralmodels of the buildings considered as a bare frame and with masonry infi ll, in order to evaluate the infl uence of infi ll wallson the failure mechanisms. Five three-storey buildings with different structural confi gurations and detailing were selected.The effect of masonry infi ll panels on structural response was delineated by comparing the bare-framed response with theinfi ll response. Seismic performance is evaluated with regard to global strength, stiffness, energy dissipation, inter-storeydrift, and total defl ection of the structure. A parametric analysis of structures with masonry infi ll is also performed. Forthis, the infl uence of different material properties is studied, namely diagonal compressive stress, modulus of elasticity andtensile stress of masonry infi ll panels. Study results show that masonry infi ll increases the global strength and stiffness ofthe structures; it decreases the inter-storey drift and hence the total displacement of the structure. The results quantify theinfl uence of the infi ll panels on structural response and, in particular, the effect of the diagonal compressive strength of themasonry wall
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