A mixed integer convex programming approach to constrained attitude guidance

This brief report introduces a new algorithm for attitude motion planning, Constrained Attitude Guidance (CAG) problem, in the presence of angular rate constraints and conic exclusion regions (pointing constraints). The CAG problem is solved by considering only the quaternion kinematics in the formulation and using constraints on quaternions and its time derivatives to indirectly apply bounds on the angular rates and accelerations. The CAG formulation makes use of Mixed Integer Convex Programming (MICP) in order to impose, approximately, the unity constraint on the quaternion magnitude, where the approximation accuracy can be set to a desired accuracy. The solution complexity of the MICP formulation increases exponentially with the number of binary variables that are used to impose the unit norm constraint on the quaternion. Since this number is independent of the number of exclusion pointing constraints, the solution approach has favorable complexity in terms of the number of pointing constraints. The report also provides a numerical example that incorporates both angular rate and pointing constraints.Aerospace Engineerin

Maternal Thyroid Dysfunction and Neonatal Thyroid Problems

Aim. To investigate obstetric features of pregnant women with thyroid disorders and thyroid function tests of their newborn infants. Methods. Women with hypothyroidism and having anti-thyroglobulin (ATG) and anti-thyroid peroxidase (anti-TPO) antibodies were assigned as group I, women with hypothyroidism who did not have autoantibodies were assigned as group II, and women without thyroid problems were assigned as group III. Results. Pregnant women with autoimmune hypothyroidism (group I) had more preterm delivery and their babies needed more frequent neonatal intensive care unit (NICU) admission. In group I, one infant was diagnosed with compensated hypothyroidism and one infant had transient hyperthyrotropinemia. Five infants (23.8%) in group II had thyroid-stimulating hormone (TSH) levels >20 mIU/mL. Only two of them had TSH level >7 mIU/L at the 3rd postnatal week, and all had normal free T4 (FT4). Median maternal TSH level of these five infants with TSH >20 mIU/mL was 6.6 mIU/mL. In group III, six infants (6.5%) had TSH levels above >20 mIU/mL at the 1st postnatal week. Conclusion. Infants of mothers with thyroid problems are more likely to have elevated TSH and higher recall rate on neonatal thyroid screening. Women with thyroid disorders and their newborn infants should be followed closely for both obstetrical problems and for thyroid dysfunction

Quantifying Robotic Swarm Coverage

In the field of swarm robotics, the design and implementation of spatial density control laws has received much attention, with less emphasis being placed on performance evaluation. This work fills that gap by introducing an error metric that provides a quantitative measure of coverage for use with any control scheme. The proposed error metric is continuously sensitive to changes in the swarm distribution, unlike commonly used discretization methods. We analyze the theoretical and computational properties of the error metric and propose two benchmarks to which error metric values can be compared. The first uses the realizable extrema of the error metric to compute the relative error of an observed swarm distribution. We also show that the error metric extrema can be used to help choose the swarm size and effective radius of each robot required to achieve a desired level of coverage. The second benchmark compares the observed distribution of error metric values to the probability density function of the error metric when robot positions are randomly sampled from the target distribution. We demonstrate the utility of this benchmark in assessing the performance of stochastic control algorithms. We prove that the error metric obeys a central limit theorem, develop a streamlined method for performing computations, and place the standard statistical tests used here on a firm theoretical footing. We provide rigorous theoretical development, computational methodologies, numerical examples, and MATLAB code for both benchmarks.Comment: To appear in Springer series Lecture Notes in Electrical Engineering (LNEE). This book contribution is an extension of our ICINCO 2018 conference paper arXiv:1806.02488. 27 pages, 8 figures, 2 table

Measurements with a Custom-Built Jumping Ring Apparatus and Determination of the Applied Net Force as a Function of Current

In this extended essay, a jumping ring setup has been established in order to find magnetic force applied on a ring as a function of applied current. A basic setup consists of a solenoid, ferromagnetic rod core and non-ferromagnetic electrically well conductive ring put on the core. In this work, however, a programmable microcontroller unit was included into the system so that time of flight of the ring could be measured. Electrical devices were also included for overcurrent protection. A set of time of flight versus jumping distance of an aluminum ring measurement has been made together with voltage and current measurements on the solenoid. Impedance of the solenoid was found using voltage-current linear curve fit. From inductance-impedance relationship, magnetic energy stored in the solenoid was calculated. Ring speeds were calculated to obtain the acceleration and hence the net force applied on the ring. Net force acting on the ring as a function of current was plotted. Finally, it was surprisingly observed that jump height increases as the mass of ring increases within a certain mass range

Hava Trafik Kontrolünde Kontrolör Kararları Nedeni İle Oluşan Gecikmelerin Analizi

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013 Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013 Bu çalışmada iki farklı veri seti kullanılarak, Avrupa Hava Sahası üzerinde bir takım analizler gerçekleştirilmiş ve bu hava sahasını modelleme yöntemlerinin verimliliği üzerinde durulmuştur. Öncelikle, Hava Trafiği modellerine ön ayak olması amacı ile Avrupa Hava Sahası üzerinde bulunan hava alanlarının ve hava limanlarının ayrı ayrı bağlantı grafları analizler için kullanılan veri setleri üzerinden oluşturulmuş ve trafik akışının karakteristikleri hakkında bilgi edinmek amacı ile Fransa Hava Sahası incelenmiştir. Bu noktadan sonra gecikme analizlerine geçilmiş ve yaşanan gecikmeler iki farklı bakış açısı ile incelenmiştir. İlk olarak her uçuş için uçuşun geçtiği tüm hava alanları üzerinde yaşadığı gecikmeler gerçek uçulan ve planlanan sürelerin farkı ile hesaplanmış ve uçuşun bütün fazlarındaki yaşadığı gecikmeler elde edilmiştir. Bütün uçuşların sonuçlarının birleştirilmesi üzerine, Avrupa hava sahası üzerindeki gecikme üretim dağılımları ve bu dağılımların zamanla nasıl ilerlediği elde edilmiş, gecikme üretimi açısından sorunlu bölgeler saptanmıştır. İkinci bir yaklaşım olarak hava limanları ağı üzerinde gecikmelerin nasıl ilerlediği araştırılmış ve farklı bir modelleme yöntemi önerilmiştir. Bu metodun hava limanları arasında gerçekleşen tüm uçuşları ayrı ayrı incelemesi nedeni ile temsil etme kapasitesi daha yüksek bir modelleme yöntemi olduğu sonucuna varılmıştır. In this study by using two different sets of data, analyses have been conducted over European Airspace and the efficiencies for modelling techniques of European Air Traffic Network are investigated. Before all else, in order to be the initiator of an air traffic model of European Airspace, connectivity graphs of both airspaces and airports have been generated directly via utilization of data sets. To be able to have an insight about air traffic flow patterns and characteristics France Airspaces have been analyzed. From that point on, delay propagation analyses have been conducted and delays have been investigated with two different approach. Firstly, for every flight, delay of each crossed airspace has been calculated by seeking the difference between planned and actual data. Aggregation of all these delay data from every flight resulted with the distribution of delay generations across the whole European Airspace. Moreover, utilizing this method in a long time interval yielded the propagation of delays through time and gathering all these results together pointed out the congested regions with generally and/or highly delay generating regions. As a secondary modelling approach, analyses have been conducted over the connectivity graph of airports. All flights between each airport pair have been investigated along with airport analyses implemented with all flights regarding those airports. It has been observed that the second approach provides a more representative modelling method because it compares the flights between airport pairs with all other flights which gives more inferences for the reasons of delays and their propagations. Yüksek Lisans M.Sc

A Mobile Location-Aware Recommendation System

Copyright © 2014 SCITEPRESS - Science and Technology Publications All rights reserved.Improvements in mobile technology provide greater personal information accessibility, data incorporation, and public resources accessibility, "anytime, anywhere". Smartphones are not only devices that make phone calls, but have also become a gateway to the Internet. Mobile devices offer the capabilities of usage flexibility, mobility, fast wireless communication, and location-awareness. Location is determined by GPS satellite tracking, position relative to GSM base stations, and the device's media access control. Similarly, usage of social networks is increasing steadily. Widespread usage of social networks introduces new requirements of Internet application. Users of such networks share their ideas and interests, as well as the activities they plan to attend. In addition, they follow other users' information and shape their planned activities accordingly. In this study, an intelligent context-aware system is described. In this field, contextawareness is a mobile paradigm in which applications can discover and take advantage of contextual information, such as user location, nearby people and devices, and user activity. This system provides an activity list that users plan to attend. Our recommender system creates results based on data mining techniques, by using personal identification data and user activities. The recommender system brings novel methodology to the activity-decision process by utilizing the right location and real-time information

Historical demography of the Eurasian green woodpecker: integrating phylogeography and ecological niche modelling to test glacial refugia hypothesis

WOS: 000366240500009In this study, we re-evaluated historical demography of the Eurasian green woodpecker (Picus viridis) on the basis of previously published multi-locus mitochondrial DNA (mtDNA) data and ecological niche modelling. We particularly aimed to test glacial refugia hypothesis during climatic oscillations of the late Quaternary for the Eurasian green woodpecker. Our results indicate that the Eurasian green woodpecker was sensitive to the effects of climate change. Prior to the Last Glacial Maximum (22000 years ago), the population contraction started and the Eurasian green woodpecker restricted its range to southern Europe (including France), Anatolia, and the Caucasus/Caspian region, and, afterwards, substantially expanded its range from this restricted area to its present range around 14500 years before present. Therefore, during the Last Glacial Maximum, we recognize a single large refugium for this species, located in southern Europe (including France), Anatolia, and the Caucasus/Caspian region