2,405 research outputs found
Comparisons of lactation of the giant panda female YANG YANG of the single cubs FU LONG (FL) 2007, FU HU (FH) 2010 and the twins FU FENG (FF) & FU BAN (FB) 2016) during the first 12 weeks after parturition.
No full textComparisons of lactation of the giant panda female YANG YANG of the single cubs FU LONG (FL) 2007, FU HU (FH) 2010 and the twins FU FENG (FF) & FU BAN (FB) 2016) during the first 12 weeks after parturition.</p
The Aresys FF-SAR Service for Cryosat-2 at ESA GPOD
No full textThe Fully-Focused SAR (FF-SAR) processing, introduced in Egido and Smith (2016) allows obtaining a maximum resolution of 0.5 m in the along-track direction. It provides significant benefits for inland water altimetry investigations allowing the successful investigation of very small rivers and canals (Kleinherenbrink, 2020) that are typically harder to be analysed by using unfocused Delay-Doppler SAR (DD-SAR) data (about 300 m resolution in the along-track direction).In its development, two major limitations were associated with the FF-SAR processing: 1) the presence of evenly spaced high sidelobes in the Point Target Response (PTR) due to the closed-loop burst mode implemented in Sentinel-3 & Cryosat-2 altimeter payloads, used for initial FF-SAR investigations, and 2) the heavy computational burden with respect to the unfocused DD-SAR processing. The first limitation can be overcome by designing the radar system differently adopting an open-loop transmission scheme as, for instance, the one implemented in the altimeter payload of the Sentinel-6 Michael Freilich mission, launched on 21 November 2020. The second limitation has been addressed in research works following Egido and Smith (2016) indicating that an improvement in terms of computational burden can be achieved by adopting algorithms in the frequency domain (Guccione et al., 2018).Being the role of FF-SAR for future inland water altimetry well understood, along with the possibility to see it implemented with reduced drawbacks during the Sentinel-6 Michael Freilich mission, a collaboration has started between the ESA GPOD Team, already hosting the successful SARvatore services portfolio for unfocused SAR & SARin altimetry, and Aresys. Aresys has developed a generic FF-SAR prototype processor, that is able to process data acquisition from different instruments and exploiting the frequency-domain Omega-K algorithm (Guccione et al., 2018 & Scagliola et al., 2018). The Aresys's FFSAR prototype processor for CryoSat-2 allows users to process, on line and on demand, low-level CryoSat FBR products in SAR mode up to FF-SAR Level-1 products with self-customized options. Additionally a wide set of processing parameters is configurable, allowing as an example to select the along-track resolution or to obtain FFSAR multilooked waveforms at the desired posting rate. The collaboration led to the creation of a new service for the processing of CryoSat Baseline D data in FF-SAR mode. Users will be able to select the following options: 1) range oversampling factor, 2) bandwidth factor (responsible for the along-track resolution value) and 3) multilook posting rate (1Hz-500Hz). Geophysical corrections and L2 estimates from both a threshold peak retracker and an ALES-like subwaveform retracker are part of the output package. In preliminary open ocean analyses, very good results on SSH noise have been obtained by the ALES-like subwaveform retracker.In this presentation, the Aresys FF-SAR prototype processor is described and the outcome of some preliminary validation activities, performed by a group of altimetry researchers, is reported. The service is scheduled to open to all GPOD/SARvatore users in the first semester of 2021. Future evolutions should include the extension of the service to Sentinel-3 and Sentinel-6 data.Astrodynamics & Space Mission
The Devil's altar? : crime and the early modern public house
Get PDFWas the early modern public house really such a dangerous place, as Puritan preachers (and many historians) suggested? This article discusses offences by publicans and patrons. It argues that the evidence for crime needs to be carefully contextualised and that taverns could stabilise as well as threaten the social order
Comparisons of a) resting behaviours, b) mean interactions of the giant panda female YANG YANG with the single cubs FU LONG (FL) 2007, FU HU (FH) 2010 and the twins FU FENG (FF) & FU BAN (FB) 2016) during the first 12 weeks after parturition.
No full textComparisons of a) resting behaviours, b) mean interactions of the giant panda female YANG YANG with the single cubs FU LONG (FL) 2007, FU HU (FH) 2010 and the twins FU FENG (FF) & FU BAN (FB) 2016) during the first 12 weeks after parturition.</p
Human motion retrieval based on freehand sketch
No full textIn this paper, we present an integrated framework of human motion retrieval based on freehand sketch. With some simple rules, the user can acquire a desired motion by sketching several key postures. To retrieve efficiently and accurately by sketch, the 3D postures are projected onto several 2D planes. The limb direction feature is proposed to represent the input sketch and the projected-postures. Furthermore, a novel index structure based on k-d tree is constructed to index the motions in the database, which speeds up the retrieval process. With our posture-by-posture retrieval algorithm, a continuous motion can be got directly or generated by using a pre-computed graph structure. What's more, our system provides an intuitive user interface. The experimental results demonstrate the effectiveness of our method. © 2014 John Wiley & Sons, Ltd
Flexible time–space network formulation and hybrid metaheuristic for conflict-free and energy-efficient path planning of automated guided vehicles
No full textOperations of Automated Guided Vehicles (AGVs) are desired to be more energy-efficient while maintaining high transport productivity, motivated by the green production requirements. This paper investigates a new energy-efficient planning problem for determining conflict-free paths of the AGVs in its transport roadmap. In this problem, the vehicle path and transport time in the roadmap are jointly optimized, based on a flexible time–space network (FTSN). We provide the mathematical problem formulation of the energy-efficient path planning problem. The resulting optimization problem is proved to be a non-convex mixed-integer nonlinear programming which is computationally intractable. We further propose a hybrid metaheuristic that integrates the genetic algorithm and estimation of the distribution algorithm to improve its computational efficiency. Numerical results show the effectiveness of the developed algorithm based on the FTSN framework, compared to the existing metaheuristics, the conventional path planning method, and a commercial solver. The proposed method has a wide application in improving energy use of material handling, providing a guiding significance on promoting cleaner production of flexible manufacturing systems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic
Optimal Configuration of Omega-Kappa FF-SAR Processing for Specular and Non-Specular Targets in Altimetric Data: The Sentinel-6 Michael Freilich Study Case
No full textIn this study, the full-focusing (FF) algorithm is reviewed with the objective of optimizing it for processing data from different types of surfaces probed in altimetry. In particular, this work aims to provide a set of optimal FF processing parameters for the Sentinel-6 Michael Freilich (S6-MF) mission. The S6-MF satellite carries an advanced radar altimeter offering a wide range of potential FF-based applications which are just beginning to be explored and require prior optimization of this processing. In S6-MF, the Synthetic Aperture Radar (SAR) altimeter acquisitions are known to be aliased in the along-track direction. Depending on the target, aliasing can be tolerated or may be a severe impairment to provide the level of performance expected from FF processing. Another key aspect to consider in this optimization study is the unprecedented resolution of the FF processing, which results in a higher posting rate than the standard SAR processing. This work investigates the relationship between posting rate and noise levels and provides recommendations for optimal algorithm configurations in various scenarios, including transponder, open ocean, and specular targets like sea-ice and inland water scenes. The Omega–Kappa (WK) algorithm, which has demonstrated superior CPU efficiency compared to the back-projection (BP) algorithm, is considered for this study. But, unlike BP, it operates in the Doppler frequency domain, necessitating further precise spectral and time domain settings. Based on the results of this work, real case studies using S6-MF acquisitions are presented. We first compare S6-MF FF radargrams with Sentinel-1 (S1) images to showcase the potential of optimally configured FF processing. For highly specular surfaces such as sea-ice, distinct techniques are employed for lead signature identification. S1 relies on image-based lineic reconstruction, while S6-MF utilizes phase coherency of focalized pulses for lead detection. The study also delves into two-dimensional wave spectra derived from the amplitude modulation of image/radargrams, with a focus on a coastal example. This case is especially intriguing, as it vividly illustrates different sea states characterized by varying spectral peak positions over time.Astrodynamics & Space Mission
Reliability control of single-epoch RTK ambiguity resolution
No full textReliability is an important indicator of GNSS performance, especially for the safety-critical applications. Carrier phase-based GNSS positioning can achieve high precision, but its reliability depends on the ambiguity resolution reliability. The ambiguity acceptance test is a popular way to improve the reliability of ambiguity resolution, although the popular ratio test with empirical threshold is not capable of controlling the reliability. A fixed failure rate (FF) approach has been proposed to solve this problem from a theoretical prospective, but its performance has not been verified with real GNSS data. In this study, the threshold function method is used to calculate the FF-difference test threshold; its performance in single-epoch RTK situation is evaluated with two GPS data sets. The numerical results indicate that the threshold function can control the failure rate of ambiguity resolution according to the user requirements. The ratio test also performs well, but it obtains different failure rates for different baselines using a particular empirical threshold. The FF-difference test outperforms the ratio test in the short-baseline case since the inaccurate variance factor degrades its performance. The performance of the FF-difference test can be improved if a better stochastic model is applied
"Francisco Pizarro" de Rosa Arciniega: Un intento de legitimacion de la voz de una historiadora
Get PDFA reading of the historical novel Francisco Pizarro, written by the Peruvian Rosa Arciniega in 1936, is proposed. Through the analysis of the work, we will reflect on the relationship of the writer with the national historiography and with the ideal of a woman who dominated Latin American political and cultural discourse in the first half of the 20th century. From this, we seek to identify the place that the author constructs for herself within the intellectual field
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