A virtual reference satellite differential method for relative correction of satellite ephemeris errors

2010 ◽  
Vol 53 (12) ◽  
pp. 2300-2306
Author(s):  
ChengLin Cai ◽  
XiaoHui Li ◽  
HaiTao Wu
2017 ◽  
Vol 137 (7) ◽  
pp. 884-890 ◽  
Author(s):  
Yoshihiro Matsui ◽  
Hideki Ayano ◽  
Shiro Masuda ◽  
Kazushi Nakano
Keyword(s):  

Author(s):  
Martina M. King

Libraries use icons (visual representations) on their websites to draw attention to features and services. How are library staff to evaluate their icons? This session reports the results of a thesis study which examines and assesses a selection of virtual reference icons from Association of Research Library websites.Les bibliothèques utilisent des icônes (représentations visuelles) sur leur site Web pour attirer l'attention sur certains éléments et services. Quelle est l'aptitude des employés de bibliothèques pour évaluer ces icônes? Cette séance présente les résultats d'une étude de thèse qui examine et mesure une gamme d'icônes de référence virtuelle trouvés sur les sites Web des membres de l'Association of Research Library. 


Author(s):  
O. M. Reva ◽  
V. V. Kamyshin ◽  
S. P. Borsuk ◽  
V. A. Shulhin ◽  
A. V. Nevynitsyn

The negative and persistent impact of the human factor on the statistics of aviation accidents and serious incidents makes proactive studies of the attitude of “front line” aviation operators (air traffic controllers, flight crewmembers) to dangerous actions or professional conditions as a key component of the current paradigm of ICAO safety concept. This “attitude” is determined through the indicators of the influence of the human factor on decision-making, which also include the systems of preferences of air traffic controllers on the indicators and characteristics of professional activity, illustrating both the individual perception of potential risks and dangers, and the peculiarities of generalized group thinking that have developed in a particular society. Preference systems are an ordered (ranked) series of n = 21 errors: from the most dangerous to the least dangerous and characterize only the danger preference of one error over another. The degree of this preference is determined only by the difference in the ranks of the errors and does not answer the question of how much time one error is more dangerous in relation to another. The differential method for identifying the comparative danger of errors, as well as the multistep technology for identifying and filtering out marginal opinions were applied. From the initial sample of m = 37 professional air traffic controllers, two subgroups mB=20 and mG=7 people were identified with statisti-cally significant at a high level of significance within the group consistency of opinions a = 1%. Nonpara-metric optimization of the corresponding group preference systems resulted in Kemeny’s medians, in which the related (middle) ranks were missing. Based on these medians, weighted coefficients of error hazards were determined by the mathematical prioritization method. It is substantiated that with the ac-cepted accuracy of calculations, the results obtained at the second iteration of this method are more ac-ceptable. The values of the error hazard coefficients, together with their ranks established in the preference systems, allow a more complete quantitative and qualitative analysis of the attitude of both individual air traffic controllers and their professional groups to hazardous actions or conditions.


Author(s):  
Matteo Facchino ◽  
Atsushi Totsuka ◽  
Elisa Capello ◽  
Satoshi Satoh ◽  
Giorgio Guglieri ◽  
...  

AbstractIn the last years, Control Moment Gyros (CMGs) are widely used for high-speed attitude control, since they are able to generate larger torque compared to “classical” actuation systems, such as Reaction Wheels . This paper describes the attitude control problem of a spacecraft, using a Model Predictive Control method. The features of the considered linear MPC are: (i) a virtual reference, to guarantee input constraints satisfaction, and (ii) an integrator state as a servo compensator, to reduce the steady-state error. Moreover, the real-time implementability is investigated using an experimental testbed with four CMGs in pyramidal configuration, where the capability of attitude control and the optimization solver for embedded systems are focused on. The effectiveness and the performance of the control system are shown in both simulations and experiments.


Author(s):  
Li Jun ◽  
Li Li ◽  
Zhang Yongxiang ◽  
Chu Zhigang ◽  
Fan Xiaopeng

In China, noise pollution from substations in urban areas is becoming more and more serious. An annoyance evaluation of the noise emitted by urban substations is presented. First, the subjective evaluation is conducted on the noise samples from urban substations via the semantic differential method. Subsequently, according to the typical characteristics of urban substation noise, 14 acoustical metrics are used to describe the noise samples for objective evaluation. Then the correlation analysis and regression analysis between the objective and subjective evaluation results are carried out. Finally, a regression model for urban substation noise evaluation is established. Practical application shows that the regression model can correctly predict the subjective annoyance of urban substation noise.


2021 ◽  
Vol 13 (14) ◽  
pp. 7899
Author(s):  
Ming-Chyuan Ho ◽  
Yung-Chia Chiu

The urban landscape can be improved to reduce the stress experienced by citizens. Therefore, stress-relieving buildings constitute a crucial topic and a future trend in architecture and design. In this study, different architectural styles were investigated to explore design methods for and characteristics of stress-relieving building shapes and to identify indicators for measuring participant stress relief while viewing buildings. To understand stress relief from architecture, we performed semi-structured interviews with 60 participants who viewed images of 30 buildings. The semantic differential method with a 7-point image scale was used to rate stress relief from different architectural styles. The study results revealed that the participants perceived curvilinear buildings as interesting but do not relieve stress. The participants identified as feeling high pressure considering rectilinear patterns to relieve more stress. To support this observation, we identified three principles—city image, identity, and spiritual atmosphere—as fundamental loci of designing cities for livability. We illustrate the three principles with several cases that facilitate a detailed understanding of their applicability in biodesign practices.


2010 ◽  
Vol 17 (9) ◽  
pp. 36-39 ◽  
Author(s):  
Xue-song Wang ◽  
Yan Peng ◽  
Li-pu Xu ◽  
Hong-min Liu

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