Local descriptors for visual SLAM

We present a comparison of several local image descriptors in the context of visual Simultaneous Localization and Mapping (SLAM). In visual SLAM a set of points in the environment are extracted from images and used as landmarks. The points are represented by local descriptors used to resolve the association between landmarks. In this paper, we study the class separability of several descriptors under changes in viewpoint and scale. Several experiments were carried out using sequences of images in 2D and 3D scenes

Interest point detectors for visual SLAM

In this paper we present several interest points detectors and we analyze their suitability when used as landmark extractors for vision-based simultaneous localization and mapping (vSLAM). For this purpose, we evaluate the detectors according to their repeatability under changes in viewpoint and scale. These are the desired requirements for visual landmarks. Several experiments were carried out using sequence of images captured with high precision. The sequences represent planar objects as well as 3D scenes

Performance conference board of amnesty remiss and penalty payments nationwide

Solución de la problemática de los ciudadanos que se encuentran en condición de remisos a nivel nacional, y continuación del proceso de la definición de la situación militar.Solving the problems of citizens who are in condition remiss at national level, and continuing the process of defining the military situation

Finite Element Modeling of Rubber Bushing for Crash Simulation - Experimental Tests and Validation

Until recently, the general level of detail in full car crash models has not allowed a physical modeling of rubber bushings with solid elements. This is partly because of the difficulty in modeling the complex characteristic of rubber, but also due to limited understanding of the mechanical properties of rubber materials. The main focus of this Master’s thesis project is to develop a new and improved finite element modeling of rubber bushings for crash simulation, including the model of the bolt joint, which keep the rubber bushing linked to the body structure of the car. The final FE-model has to be able to mimic the real mechanical behavior of the rubber bushing and work effectively in the full-vehicle crash simulation. To achieve this, the program for non-linear dynamic analysis of structures in three dimensions LS-DYNA was used. In order to validate the final FE-model of the rubber bushing system testing activities and comparisons between the full-vehicle crash simulation with the new and improved FE-model of rubber bushing and the traditional one that often is used in the simulations were made. The experimental activities were carried out in the tower test of the Safety Centre of Volvo Car Corporation. In the first part of the thesis, comparisons between the finite element analysis and analytical solution of a simple cylindrical model of rubber exposed to shock loading as well as an estimation of the shear modulus G using the strain energy function of the Yeoh model and an energy balance has been done. The results from the FE-simulation corresponded quite well with the ones from the analytical solution when the Yeoh model is used as the hyperelastic rubber material to model the properties of the rubber. Regarding the FE-model of the rubber bushing system, the rubber part of the bushing was modeled in a rough way. This is because holes, fillets and other design features within the geometry of the rubber bushing rapidly increase the number of elements needed and, as a result, the computational cost of the analysis and the stability of the model are affected. Therefore, the smaller parts of rubber at the surface of the plastic outer sleeve, aluminum inner sleeve and at the corners while meshing the rubber bushing were not taken into account. The rubber bushing and the screw joint were modeled using 8-node solid elements, 4-node and 3-node shell elements and, 2-node beam elements. The 8-node solid elements were used for the rubber, the aluminum inner sleeve and the bolt head, the 4-node and 3-node shell elements were used for the plastic outer sleeve, the washer, the big nut and the cylindrical casing of the bolt, and the 2-node beam elements were used for the thread and the grip of the bolt. The Yeoh model was used to describe the hyperelastic behaviour of the rubber and for the rest of the model, the evaluated material models were mostly characterized by using elastic piecewise linear plasticity with a specific curve stress/strain and a yield strength. The contacts between metal and metal surfaces and between the rubber and the plastic outer sleeve were solved by using the simple global contact and the LS-DYNA option TIED_NODES_TO_SURFACE_OFFSET, respectively. The tightening of the bolt joint was taken into consideration in order to properly describe the friction and contacts between the different parts of the complete rubber bushing system from the beginning of the simulation. The rubber itself turned out to be just a small part of the complete rubber bushing system, so it was not necessary to use a complex material model to predict the physical response of the rubber. A simple and purely hyperelastic rubber material model where no damping exists was used instead. The Yeoh model worked out to be a stable model at high strain rate and therefore was used with theses material parameters: C10 = 0,55, C20 = 0,05, C30 = 0,95. The developed FE-model of rubber bushing system seems to model the nonlinearities in the system as large displacement effects and large deformations, material nonlinearity, and boundary nonlinearities. This is confirmed by the preload in the bolt joint, the contacts, the friction between the different surfaces and the bending and pulling out behaviour of the system working properly at the beginning and during the simulation. In order to validate the final FE-model of the rubber bushing system it was exposed to different loading cases in the FE-simulations and full-scale tests. The FE-simulations were tested under the same conditions as in the experimental tests in order to have a reference for comparisons. The full-scale impacts and computed deformations agreed qualitatively but they differed in magnitude. The deformations of the rubber bushing system, due to the bending moment, axial force and pulling out between sleeves appear to be similar to what happens in reality. The reason for the inaccuracies may be caused by several approximations in the FEmodel and others source of error while carrying out the different experimental test. An US-NCAP analysis was also performed in LS-DYNA in order to be sure that the final FE-model of the rubber bushing system works properly in the full-vehicle crash simulation. The simulation provided satisfactory results in the full-frontal impact of the car showing a significant improvement in the behavior of the rubber bushing system in comparison with the full-vehicle crash simulation of the traditional FE-model of rubber bushing that is often used in the car. Finally, the final FE-model of rubber bushing system can be considered reliable and can be used with a high rate of confidence in the full-vehicle crash simulation, since the computational time can be reduced by up to 4 % approximately and when used in the full vehicle crash simulation, this model is more physical and detailed than the traditional one and can better resemble the mechanical behaviour of the real rubber bushing system

From Stateless to Citizen: Trust, Disclosure, and Collaboration with Guatemalan Refugees as Human Rights Practice

U.S. immigration enforcement practices have spread to Mexico, resulting in apprehension rates of Central American migrants that rival those of the U.S. In 2015, deportations of migrants from Guatemala, Honduras, and El Salvador in Mexico exceeded 165,000, more than twice the number of U.S. deportations to this region. Enforcement-only priorities surrounding immigration policy in Mexico have reinforced discriminatory treatment, poverty, inequality, and exploitation toward the indigenous and migrant populations. These circumstances have particularly impacted indigenous Guatemalan Mayans who sought refuge in Mexico during the 1980s and continue to face obstacles for their legalization by the Mexican state, in violation of their human rights. Specifically, I will share ethnographic findings from a three-year collaboration to obtain legalization for indigenous Mayans from Guatemala who for more than thirty years remained stateless in Mexico and the U.S. I will discuss how reduced legal options to regularize status created barriers to political, economic, and cultural incorporation in Mexico and the U.S. and left significant family members — documented and undocumented alike — vulnerable to deportations and family separations. I will also identify how legal status was obtained for twenty-six stateless subjects in late 2016. Tens of thousands who fled military conflict in Guatemala, however, remain stateless throughout the Americas. Recommendations will be made on how scholars, advocates, and practitioners concerned on the topics of conflict, mass displacement, poverty, inequality, and exploitation can promote human rights protections for this population

Human motion trajectory prediction using the Social Force Model for real-time and low computational cost applications

Human motion trajectory prediction is a very important functionality for human-robot collaboration, specifically in accompanying, guiding, or approaching tasks, but also in social robotics, self-driving vehicles, or security systems. In this paper, a novel trajectory prediction model, Social Force Generative Adversarial Network (SoFGAN), is proposed. SoFGAN uses a Generative Adversarial Network (GAN) and Social Force Model (SFM) to generate different plausible people trajectories reducing collisions in a scene. Furthermore, a Conditional Variational Autoencoder (CVAE) module is added to emphasize the destination learning. We show that our method is more accurate in making predictions in UCY or BIWI datasets than most of the current state-of-the-art models and also reduces collisions in comparison to other approaches. Through real-life experiments, we demonstrate that the model can be used in real-time without GPU's to perform good quality predictions with a low computational cost

US Immigration Enforcement and the Making of Unintended Returnees

US immigration enforcement has led to a rise in the number of deportations. Several studies identify deportees as more likely to attempt re-entry to reunify with family members in a variety of international settings. These demographic changes have prompted some scholars to theorize how deportation produces a unique mobility subject: the unintended returnee. The importance of studying unintended returnees is amplified when we examine the 3.1 million unauthorized migrants deported by the US between 2005-2013. Over 1.5 million children living in the US were impacted by these removals. Data from the US Department of Homeland Security, indicate that among those who remigrate, the majority are those with US born children. While unauthorized reentry, is not new, the forms that return migrations take reveal changes in the organization of clandestine border-crossings that heighten the risk of violence. To provide insight on how these changes may impact deportees who remigrate, this article examines the chain of events that followed a 2006 immigration work-site raid and deportation of a migrant who was separated from his US based family. The concept of clandestinity – licit and illicit strategies that enable surreptitious cross-border mobility – is employed to understand how this person, following deportation, leverages his involvement in a human smuggling network as a smuggler (coyote) to reenter without authorization. By drawing inferences from a single case, I elucidate how immigration enforcement measures, along with limited avenues for humanitarian relief, may create conditions that compel deportees to defy the power of the state to produce involuntary transnational families and rely on illicit clandestine migration services to enable family reunification

Health Coverage Expansion for the Undocumented and Potential Impacts for Unaccompanied Migrant Youth and Families in California

The objective of this article is to identify areas for future study that have the potential to close the gap in knowledge about the health needs of unaccompanied migrant youth