Las fórmulas superlativas en el español de los siglos XVIII y XIX

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Filosofía y Letras, Departamento de Filología Española. Fecha de lectura: 11/10/201

Ultra-high strength metal matrix composites (MMCs) with extended ductility manufactured by size-controlled powder and spherical cast tungsten carbide

The main challenge of particle reinforced metal matrix composites (MMCs) is balancing strength and ductility. This research uses type 420 stainless steel and spherical cast tungsten carbide (WC/W2C) with a similar powder size and range as raw powders to manufacture laser powder bed fusion (LPBF) 420 + 5 wt% WC/W2C MMCs. LPBF 420 + 5 wt% WC/W2C MMCs contain austenite, martensite, and W-rich carbides (WC/W2C, FeW3C, M6C, and M7C3) from nanometre to micrometre scale. The well-balanced composition creates a crack-free reaction layer between the reinforced particles and matrix. This reaction layer consists of two distinct layers, depending on the element concentration. The LPBF 420 + 5 wt% WC/W2C MMCs achieved an excellent compressive strength of ∼5.5 GPa and a considerable fracture strain exceeding 50 %. The underlying mechanisms for the improved mechanical properties are discussed, providing further insight to advance the application of MMCs via additive manufacturing

A Survey on Depth Ambiguity of 3D Human Pose Estimation

Depth ambiguity is one of the main challenges of three-dimensional (3D) human pose estimation (HPE). The recent strategies of disambiguating have brought significant progress and remarkable breakthroughs in the field of 3D human pose estimation (3D HPE). This survey extensively reviews the causes and solutions of the depth ambiguity. The solutions are systematically classified into four categories: camera parameter constraints, temporal consistency constraints, kinematic constraints, and image cues constraints. This paper summarizes the performance comparison, challenges, main frameworks, and evaluation metrics, and discusses some promising future research directions

A Multiple Linear Regression Model for Tropical Cyclone Intensity Estimation from Satellite Infrared Images

An objectively trained model for tropical cyclone intensity estimation from routine satellite infrared images over the Northwestern Pacific Ocean is presented in this paper. The intensity is correlated to some critical signals extracted from the satellite infrared images, by training the 325 tropical cyclone cases from 1996 to 2007 typhoon seasons. To begin with, deviation angles and radial profiles of infrared images are calculated to extract as much potential predicators for intensity as possible. These predicators are examined strictly and included into (or excluded from) the initial predicator pool for regression manually. Then, the “thinned” potential predicators are regressed to the intensity by performing a stepwise regression procedure, according to their accumulated variance contribution rates to the model. Finally, the regressed model is verified using 52 cases from 2008 to 2009 typhoon seasons. The R2 and Root Mean Square Error are 0.77 and 12.01 knot in the independent validation tests, respectively. Analysis results demonstrate that this model performs well for strong typhoons, but produces relatively large errors for weak tropical cyclones

Quality Evaluation Algorithm for Chest Compressions Based on OpenPose Model

Aiming at the problems of the low evaluation efficiency of the existing traditional cardiopulmonary resuscitation (CPR) training mode and the considerable development of machine vision technology, a quality evaluation algorithm for chest compressions (CCs) based on the OpenPose human pose estimation (HPE) model is proposed. Firstly, five evaluation criteria are proposed based on major international CPR guidelines along with our experimental study on elbow straightness. Then, the OpenPose network is applied to obtain the coordinates of the key points of the human skeleton. The algorithm subsequently calculates the geometric angles and displacement of the selected joint key points using the detected coordinates. Finally, it determines whether the compression posture is standard, and it calculates the depth, frequency, position and chest rebound, which are the critical evaluation metrics of CCs. Experimental results show that the average accuracy of network behavior detection reaches 94.85%, and detection speed reaches 25 fps

A Survey on Depth Ambiguity of 3D Human Pose Estimation

Depth ambiguity is one of the main challenges of three-dimensional (3D) human pose estimation (HPE). The recent strategies of disambiguating have brought significant progress and remarkable breakthroughs in the field of 3D human pose estimation (3D HPE). This survey extensively reviews the causes and solutions of the depth ambiguity. The solutions are systematically classified into four categories: camera parameter constraints, temporal consistency constraints, kinematic constraints, and image cues constraints. This paper summarizes the performance comparison, challenges, main frameworks, and evaluation metrics, and discusses some promising future research directions

Polar Sea Ice Monitoring Using HY-2A Scatterometer Measurements

A sea ice detection algorithm based on Fisher’s linear discriminant analysis is developed to segment sea ice and open water for the Ku-band scatterometer onboard the China’s Hai Yang 2A Satellite (HY-2A/SCAT). Residual classification errors are reduced through image erosion/dilation techniques and sea ice growth/retreat constraint methods. The arctic sea-ice-type classification is estimated via a time-dependent threshold derived from the annual backscatter trends based on previous HY-2A/SCAT derived sea ice extent. The extent and edge of the sea ice obtained in this study is compared with the Special Sensor Microwave Imager/Sounder (SSMIS) sea ice concentration data and the Sentinel-1 SAR imagery for verification, respectively. Meanwhile, the classified sea ice type is compared with a multi-sensor sea ice type product based on data from the Advanced Scatterometer (ASCAT) and SSMIS. Results show that HY-2A/SCAT is powerful in providing sea ice extent and type information, while differences in the sensitivities of active/passive products are found. In addition, HY-2A/SCAT derived sea ice products are also proved to be valuable complements for existing polar sea ice data products

Estimation of NRCS of Oil-free and Oil-covered Marine Surfaces in L-band. Assessment with UAVSAR data

International audienceThis paper presents numerical simulations and analyses of EM (electromagnetic) scattering from oil-free and oil-covered sea surface. First, the influences caused by slicks on clean sea are studied and analyzed with the action balance function. Slicks on sea surface make significant impacts on the wind input, the nonlinear wave-wave interactions and the viscous dissipation. A damping model based on the action balance equation is introduced. And then, simulations are made by assuming the surface height spectra proposed by Elfouhaily et al. and Hwang, respectively. The two scale model (TSM) is used to calculate the normalized radar cross sections (NRCS) of oil-free and oil-covered sea surfaces. Additionally, an UAVSAR image which was collected during the Deep Water Horizon oil spill accident occurred in the Gulf of Mexico is served as a reference. The numerical comparisons between simulated results and measured data have shown that, for clean sea surface, the VV polarized NRCS simulated with Elfouhaily spectrum agree well with UAVSAR data, the HV polarized NRCS simulated with Hwang spectrum agree well with UAVSAR data. For polluted sea surface, the VV polarized NRCS simulated with Elfouhaily spectrum matches well with measured data. Overall, numerical simulations with Elfouhaily spectrum seem better than Hwang spectrum inour simulations

A Modified Angular Spreading Function for Sea NRCS Estimation at Ku Band

International audienceThe sea spectrum proposed by Elfouhaily et al. is widely employed in ocean remote sensing. In this paper, we find that there exists some disagreements between the results estimated using the Elfouhaily’s angular spreading function and the empirical model NSCAT2 (which is regarded as a reliable reference in this paper). Firstly, the peak value of (k) calculated with Elfouhaily’s method monotone increases with wind speed. While the peak value of (k) estimated with the NSCAT2 first increases and then decreases with wind speed. Secondly, the wavenumber that corresponds to the peak value of (k) isn’t fixed at 363rad/m. To make the Elfouhaily’s angular spreading function agrees well with the empirical model, some modifications are made on it with numerical fitting in this paper. The numerical simulations have shown that the modified angular spreading function could provide better predictions