Flexible Trajectories Research Articles

Transformation of the System of Training Specialists during the Transition to FSES 3++

Currently, the universities in the Russian Federation are engaged in the updating of the educational programs being implemented, in accordance with the requirements of the Federal State Educational Standard 3 ++. The article provides information on the conceptual changes in the State Educational Standard, Federal State Educational Standard, and Federal State Educational Standard 3 ++ , as well as on the new opportunities universities have in connection with the introduction of the “two plus” generation standard. By an example of the project “NetworkElectronicUniversityof theRepublicofBashkortostan” the article shows the network interaction on issues of the formation of universal competences. New opportunities for universities during the transition to FSES 3 ++ are considered in the context of globalization conditions. The universities are suggested to be considered not so much as a “talent foundry”, but rather as a presence territory development driver, a space for constant positive changes (4P) due to the comprehensive development of scientific, innovative, socio-cultural activities with concurrent integration into the educational environment. The implementation of such a model within the transition to FSES 3 ++ is proposed to be done by individualizing mass education, building flexible educational trajectories that most meet the needs of the parties involved. At the same time, the so-called soft skills should become an indispensable superstructure for the formation of professional competencies, as without them it is extremely difficult to train specialists able to adapt as quickly as possible to changes in the external environment, and, in conditions of uncertainty of occupational functions in the future, they become more important than hard skills.

XAP-Lab: A software tool for designing flexible X-ray acquisition protocols

Background and objectiveThe availability of digital X-ray detectors, together with the development of new robotized hardware and reconstruction algorithms, opens the opportunity to provide 3D capabilities with conventional radiology systems. This would be based on the acquisition of a limited number of projections with non-standard geometrical configurations. The versatility of these techniques is enormous, enabling the introduction of tomography in situations where a CT system is hardly available, such as during surgery or in an ICU, or in which a reduction of radiation dose is key, as in pediatrics. Computer simulations are a valuable tool to explore these possibilities before their actual implementation on real systems. Existing software tools generally simulate only standard acquisition protocols, such as cone-beam with circular trajectory, thus not allowing the users to evaluate more sophisticated projection geometries. The goal of this work is to design a simulation tool that enables the design of acquisition protocols with flexible projection geometries. MethodsWe present XAP-Lab, a software tool for the design of X-ray acquisition protocols with flexible trajectories. For a given projection geometry, defined through a graphical user interface, it allows the user to simulate projections using GPU-accelerated kernels, the visualization of the scanned field of view and the estimation of the total radiation dose. The complete acquisition protocol can then be exported with the appropriate format for its use on real systems.We tested the software by optimizing a tomosynthesis protocol and validating the results with real acquisitions using a SEDECAL NOVA FA radiography system and phantoms for quantitative and qualitative evaluation. ResultsQuantitative evaluation using a phantom showed a mean error under 4 mm for each position, below the ±5 mm tolerance of the system specified by the manufacturer. Visual evaluation on a thorax acquisition also showed a good geometrical agreement between simulated and real projections. ConclusionsResults showed an excellent matching with simulations, supporting the usefulness of XAP-Lab for the design of new acquisition protocols with non-standard geometries.

Using spanwise flexibility of caudal fin to improve swimming performance for small fishlike robots

This paper examines the beneficial effects of the spanwise flexibility of the caudal fin for the improvement of the swimming performance for small fishlike robots. A virtual swimmer is adopted for controlled numerical experiments by varying the spanwise flexible trajectories and the spanwise flexible size of the caudal fin while keeping the body kinematics fixed. 3-D Navier-Stokes equations are used to compute the viscous flow over the robot. Elliptical, parabolic and hyperbola trajectories are chosen to describe the spanwise flexible profile of the caudal fin. According to the sign (positive or negative) of the phase difference of the swinging motion, the spanwise flexibility can be divided into the fin surface of “bow” and the fin surface of “scoop”. It is observed that for both the fin surface of “bow” and the fin surface of “scoop”, the spanwise elliptical trajectory has the optimal swimming velocity, thrust, lateral force, and efficiency. With comparisons, using the flexible caudal fin with the fin surface of “bow”, the lateral force and the power consumption can be reduced effectively and the swimming stability can be increased while reducing little the swimming velocity and thrust. Meanwhile, using the flexible caudal fin with the fin surface of “scoop” can greatly improve the swimming velocity, thrust, and efficiency while increasing part of the lateral force and the power consumption. Three-dimensional flow structures clearly indicate the evolution process around the swimming robot. It is suggested that the fish, the dolphin, and other aquatic animals may benefit their hydrodynamic performance by the spanwise flexibility of the caudal fin.

Loosely Formation-Displaced Geostationary Orbit Optimization with Complex Hybrid Sail Propulsion

To explore the performance of hybrid sail and overcome the congestion of geostationary orbit, this work proposes a method intended to optimize the trajectories of the spacecraft formation and extend the concept of displaced geostationary orbit by loosening the relative distance and introducing a station-keeping box. The multispacecraft formation is a typical complex system with nonlinear dynamics, and the hybrid propulsion system introduces additional complexity. To solve this problem, suboptimal trajectories with constant relative distance constraints are first found with inverse methods, which were referred to as ideal displaced geostationary orbits. Then, the suboptimal trajectories are used as a first guess for a direct optimization algorithm based on Gauss pseudospectral algorithm, which loosens the relative distance constraints and allows the spacecraft to be placed anywhere inside the station-keeping box. The optimization results show that the loosely formation and station-keeping box can create more flexible trajectories and achieve higher efficiency of the hybrid sail propulsion system, which can save about 40% propellant consumption.

Moving-in-pulse duration model-based target integration method for HSV-borne high-resolution radar

Hypersonic vehicles (HSVs) offer great advantages over airplanes and satellites, owing to their hypersonic speeds and flexible trajectories. However, HSV-borne radar may suffer from performance degradation if traditional target integration methods with stop-and-go (SAG) approximation are applied; this is especially true for high resolution radar and applications that utilize long-time coherent integration. In this paper, we consider the effects of moving-in-pulse duration (MPD) to derive an HSV-borne radar signal model without SAG approximation by specifically characterizing platform motion during the transmission and reception of a pulse. An explicit formula for wavenumber domain echo is derived using the 2-D joint stationary phase method. To mitigate the pulse-dependent echo distortion induced by the MPD effect, a target integration method based on the omega-K algorithm is proposed; this method employs revised filters for bulk focusing and revised Stolt interpolation for differential focusing to improve the overall focusing quality. The paper discusses the ambiguity functions of in-range MPD echo models, and describes the performance metrics for the integration results in both dimensions, including impulse response width (IRW), peak sidelobe ratio (PSLR), and integrated sidelobe ratio (ISLR). Simulation results have verified the effectiveness of the proposed method in MPD circumstances.

Understanding glocal learning spaces. An empirical study of languaging and transmigrant positions in the virtual classroom

The use of digital tools like computers and tablets in institutional learning arenas give rise to forms of flexibility where time and space boundaries become diffuse. Online learning sites are understood as being crucial today, especially in large parts of the Global North, where anyone anywhere potentially can become a student and have access to educational opportunities.This study focuses on the analysis of recorded sessions, part of an ‘Italian for (adult) beginners' online course. Our interests relate to accounting for how students negotiate different language varieties, including modalities, and how communication in virtual learning settings enables both flexible participation trajectories and identity positions in and across the boundaries of time and space.The sociocultural and dialogical analyses here are framed in terms of fluidity of ‘glocal' positions and (trans)languaging that emerge in and across time and space in Technology Mediated Communication. Our findings suggest that online environments support meaning-making where it is possible to identify alternative ways of (co)constructing and mediating learning. Such hybridity as well as the performative character of learning and identity display have important implications for online glocal communities.

Functional Analysis Based Conceptual Design of a Type of Novel Mechanical Excavator with Controllable Mechanism

Excavators can be divided into two categories: hydraulic excavator and mechanical excavator. Due to the flexibility and mobility, hydraulic excavator has almost replaced the mechanical excavator. But there still exists some problems such as hydraulic leaks and high costs of manufacturing and maintaining. On the other hand, the latter one is the excavator of choice in oil sands digging and surface mining for its durability, high productivity and low ownership costs resulting from long economic operating life, but lacks flexibility due to the structural limitations. This paper introduces an innovative design of mechanical excavator with controllable mechanism based on functional analysis of the traditional hydraulic excavator. The solving model in the form of Function-Effect-Technical Action Process-Executive Action-Mechanism (F-E-P-A-M) is used. A planar 2 Degree-OF-Freedom (DOF) controllable mechanism is adopted as the executive mechanism. A backhoe type and a face shovel type excavator both with the ability to accomplish flexible output trajectories by the joint operations of three servo-motors are proposed.

La strategia energia-clima europea nel contesto globale e le sue implicazioni per l'Italia

Energy-climate European strategy in the global framework and its implications for Italy - The article aims to analyze the implications for Italy’s of the European policy on and climate for the post-Kyoto period. Chap. 1 analyzes the and climate package adopted by the EU in June 2009, as a concrete step of the Community Strategy towards the COP 15. The article shows that the and climate package adopted before COP 15 implements two of the three unilateral targets announced in spring 2007 by the European council (reducing emissions by 20%, renewables to 20%), forgetting, however, an integrated package of measures coherent to the 20% savings target through efficiency policies. In Chap. 2 some basic features of the package have been analysed: the main strategic choices, the national objectives, the flexibility mechanisms (use of the CDM, flexible trajectories to 2020, extending the range of economic instruments and international cooperation) and the expected costs for Member States. Many incoherences have been highlighted, comprised unequal cost effects on the various EU richer countries (in terms of GDP per capita). In Chap. 3 summarizes the main implications of the EU package for Italy in terms of policies needed to implement the new rules. The benefits of innovation for European industry will depend on Italy’s ability to respond quickly to the challenge dictated by the energy package. A strong effort on efficiency policies is needed to comply with the formal GHG and renewable targets, if the maximization of social, economic and environmental opportunities is what the EU in willing for.

Long-term CO 2 emissions reduction target and scenarios of power sector in Taiwan

This study analyses a series of carbon dioxide (CO 2) emissions abatement scenarios of the power sector in Taiwan according to the Sustainable Energy Policy Guidelines, which was released by Executive Yuan in June 2008. The MARKAL-MACRO energy model was adopted to evaluate economic impacts and optimal energy deployment for CO 2 emissions reduction scenarios. This study includes analyses of life extension of nuclear power plant, the construction of new nuclear power units, commercialized timing of fossil fuel power plants with CO 2 capture and storage (CCS) technology and two alternative flexible trajectories of CO 2 emissions constraints. The CO 2 emissions reduction target in reference reduction scenario is back to 70% of 2000 levels in 2050. The two alternative flexible scenarios, Rt4 and Rt5, are back to 70% of 2005 and 80% of 2005 levels in 2050. The results show that nuclear power plants and CCS technology will further lower the marginal cost of CO 2 emissions reduction. Gross domestic product (GDP) loss rate in reference reduction scenario is 16.9% in 2050, but 8.9% and 6.4% in Rt4 and Rt5, respectively. This study shows the economic impacts in achieving Taiwan's CO 2 emissions mitigation targets and reveals feasible CO 2 emissions reduction strategies for the power sector.

Multimodal encoding in a cortical model for spatial navigation planning

According to experimental evidence, spatial navigation planning is likely to rely upon a distributed neural network spanning limbic and cortical brain structures. This network includes (i) the hippocampus, which mediates robust spatial representations, and (ii) neocortical structures, such as the prefrontal cortex, which participate in the elaboration of more abstract contextual descriptions (e.g., accounting for motivation-dependent memories and action cost/risk constraints). In order to investigate this working hypothesis, we model the interaction between the hippocampus [1] and the prefrontal cortex [2]. We focus on the cortical columnar organization to study a neuromimetic architecture suitable for spatial navigation planning. We validate the system's learning performance on a classical spatial behavioural task, the Tolman & Honzik's detour protocol [3], which suggests that rodents can plan flexible goal-directed trajectories in the presence of blocked pathways. We also put forth a set of statistical analyses to assess the spatial coding properties of the model hippocampal place and cortical column cells.

Central pattern generators based on Matsuoka oscillators for the locomotion of biped robots

Biologically inspired control approaches based on central pattern generators (CPGs) with neural oscillators have been drawing much attention for the purpose of generating rhythmic motion for biped robots with human-like locomotion. This article describes the design of a neural-oscillator-based gait-rhythm generator using a network of Matsuoka oscillators to generate a walking pattern for biped robots. This includes the proper consideration of the oscillator’s parameters, such as a time constant for the adaptation rate, coupling factors for mutual inhibitory connections, etc., to obtain a stable and desirable response from the network. The article examines the characteristics of a CPG network with six oscillators, and the effect of assigning symmetrical and asymmetrical coupling coefficients among oscillators within the network structure under different possible inhibitions and excitations. The kinematics and dynamics of a five-link biped robot have been modeled, and its joints are actuated through simulation by the torques output from the neural rhythm generator to generate the trajectories for hip, knee, and ankle joints. The parameters of the neural oscillators are tuned to achieve flexible trajectories. The CPG-based control strategy is implemented and tested through a simulation.

Optimization of Flexible Approach Trajectories Using a Genetic Algorithm

Current air traffic management in the terminal area is based on published sets of standard routes. However, a new procedure called the continuous descent approach has been recently proposed to decrease noise disturbances. To allow increased use of continuous descents and simultaneously increase performance in terms of other important aspects such as throughput, it may be beneficial to replace the predetermined fixed approach trajectories with more flexible trajectories instead. This is studied through optimizing approach trajectories, for which a genetic algorithm is used. Analyses show that allowing more flexibility in the approach routes can increase throughput, enable scheduling trajectories closer to continuous descent approaches, and result in routing flights less often over residential areas. However, it is also shown that flexible approach trajectories may increase airspace complexity, which in effect may make the task of air traffic control more complicated. Nomenclature a = longitudinal acceleration, dVC/dt CR H = mean maximum horizontal closure rate CR V = mean maximum vertical closure rate d = time deviation ˆ E = energy rate demand F = objective function value f = fitness h = altitude L = noise load on community; length M = number of segments N = number of flights N8 = maximum number of aircraft pairs with less than 8-n mi (14.82 km) horizontal distance N13 = maximum number of aircraft pairs with less than 13-n mi (24.08 km) horizontal distance Nac = maximum number of aircraft with an altitude change rate over 500 ft/min (2.54 m/s) NC = number of crossings points between arrival and departure flows Npk = peak number of aircraft simultaneously in the terminal area Nsc = maximum number of aircraft with an airspeed change greater than 10 kn (5.14 m/s) during a 2-min interval R = radius SH = mean minimum horizontal separation distance SV = mean minimum vertical separation distance T = segment type; throughput VC = calibrated airspeed Vg = ground speed γ = flight-path angle

Validation of a Long-Range Trajectory Model Using Gas Balloon Tracks from the Gordon Bennett Cup 95

Abstract In September 1995, 18 gas balloon teams competed at the Gordon Bennett Cup, a long-distance ballooning event. The landing positions, travel times of all teams, and detailed information on the tracks of four teams are available. A special version of the trajectory model FLEXTRA (flexible trajectories) is used that allows the heights of calculated trajectories to be adjusted to the respective balloon heights at every computation time step. The comparison of calculated and observed balloon trajectories allows a validation of the trajectory model. In this case study, the agreement between calculated and balloon trajectories was good, with average relative transport errors of less than 20% of the travel distance after 46 h of travel time. Most of the trajectory errors originate from interpolation errors and from amplifications of small position disturbances in divergent wind fields. Trajectory ensembles, taking into account stochastic errors occurring during the trajectory calculations, are shown to be very reliable in assessing the uncertainties of the computed trajectories. In the present study, the balloon tracks were enveloped by the ensemble trajectories most of the time, suggesting that errors in the analyzed wind fields were relatively small.

Instrumentation analysis using parameter estimation of simulated data

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