Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
Abstract: The 3Cat-3/MOTS (3: Cube, Cat: Catalunya, 3: 3rd CubeSat mission/MissiÃ?³ ObservaciÃ?³\nTerra SatÃ?¨lÃ?·lit) mission is a joint initiative between the Institut CartogrÃ? fic i GeolÃ?²gic de Catalunya\n(ICGC) and the Universitat PolitÃ?¨cnica de Catalunya-BarcelonaTech (UPC) to foster innovative\nEarth Observation (EO) techniques based on data fusion of Global Navigation Satellite Systems\nReflectometry (GNSS-R) and optical payloads. It is based on a 6U CubeSat platform, roughly a 10 cm\nÃ?â?? 20 cm Ã?â?? 30 cm parallelepiped. Since 2012, there has been a fast growing trend to use small satellites,\nespecially nanosatellites, and in particular those following the CubeSat form factor. Small satellites\npossess intrinsic advantages over larger platforms in terms of cost, flexibility, and scalability, and may\nalso enable constellations, trains, federations, or fractionated satellites or payloads based on a large\nnumber of individual satellites at an affordable cost. This work summarizes the mission analysis\nof 3Cat-3/MOTS, including its payload results, power budget (PB), thermal budget (TB), and data\nbudget (DB). This mission analysis is addressed to transform EO data into territorial climate variables\n(soil moisture and land cover change) at the best possible achievable spatio-temporal resolution....
Attitude error models play an important role in analyzing the characteristics of navigation\nerror propagation for the design and operation of strapdown inertial navigation systems (SINS).\nHowever, the majority of existing attitude error models focus on misalignment, rather than Euler\nangle errors. Misalignment cannot directly describe attitude error propagation, which is an indirect\nmeasurement. To solve the problem, a general Euler angle error model of SINS is proposed. Based on\nEuler angle error propagation analysis, relative Euler angle errors, and convected Euler angle errors\nare introduced to compose the general Euler angle error model. Simulation experiments are carried\nout to verify the proposed model....
Comparison of high-performance time scales generated by atomic clocks in laboratories of time and frequency metrology is usually\nperformed by means of the Common Viewmethod. Laboratories are equipped with specialized GNSS receivers whichmeasure the\ndifference between a local time scale and a time scale of the selected satellite. Every receiver generates log files in CGGTTS data\nformat to record measured differences. In order to calculate time differences recorded by two receivers, it is necessary to obtain\nthese logs from both receivers and process them. This paper deals with automation and speeding up of these processes....
In view of the characteristics of high risk and high accuracy in cranio-maxillofacial surgery, we present a novel surgical robot\nsystem that can be used in a variety of surgeries. The surgical robot system can assist surgeons in completing biopsy of skull base\nlesions, radiofrequency thermocoagulation of the trigeminal ganglion, and radioactive particle implantation of skull base malignant\ntumors. This paper focuses on modelling and experimental analyses of the robot system based on navigation technology. Firstly, the\ntransformation relationship between the subsystems is realized based on the quaternion and the iterative closest point registration\nalgorithm. The hand-eye coordination model based on optical navigation is established to control the end effector of the robot\nmoving to the target position along the planning path. The closed-loop control method, ââ?¬Å?kinematics + opticsââ?¬Â hybrid motion\ncontrol method, is presented to improve the positioning accuracy of the system. Secondly, the accuracy of the system model was\ntested by model experiments. And the feasibility of the closed-loop control method was verified by comparing the positioning\naccuracy before and after the application of the method. Finally, the skull model experiments were performed to evaluate the\nfunction of the surgical robot system. The results validate its feasibility and are consistent with the preoperative surgical planning....
Transcranial electrical stimulation (tES) uses low intensity current to alter neuronal activity\nin superficial cortical regions, and has gained popularity as a tool for modulating several\naspects of perception and cognition. This mini-review article provides an overview of\ntES and its potential for modulating spatial processes underlying successful navigation,\nincluding spatial attention, spatial perception, mental rotation and visualization. Also\nconsidered are recent advances in empirical research and computational modeling\nelucidating several stable cortical-subcortical networks with dynamic involvement in\nspatial processing and navigation. Leveraging these advances may prove valuable\nfor using tES, particularly transcranial direct and alternating current stimulation\n(tDCS/tACS), to indirectly target subcortical brain regions by altering neuronal activity in\ndistant yet functionally connected cortical areas. We propose future research directions\nto leverage these advances in human neuroscience....
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