Violence and Public Safety as a Democratic Simulacrum in Brazil

This paper analyzes actions taken by eight special programs for homicide reduction implemented in the states of Bahia, Ceará¡, Espí­rito Santo, Minas Gerais, Pernambuco, Rio de Janeiro and São Paulo, as well as the Brazilian Federal District. It aims to understand the historical permanence of lethal violence as one of the most striking social characteristics of Brazil and defends the argument that the prevention and tackling of homicides – understood in a broad sense that includes all intentional violent deaths – are operated, both politically and institutionally, from a symbolic simulacrum that causes incremental initiatives to fail to reach the architecture of criminal justice and public security institutions. As structural reforms in the criminal justice and public security system face several obstacles to being approved by the Legislative Branch, this simulacrum makes the police force and other institutions belonging to the system to continue operating from a center of criminal policies that do not depend on the construction of a democratic project of public security, protection of life or civil and human rights. The study reiterates that the debate on transparency and data quality can allow actions to strengthen institutional capacity for monitoring and evaluation and/or strategic litigation, which in turn may weaken of the path dependence and worldviews that operate the identified simulacrum. In other words, the debate on transparency and data quality is one of the strongest battlefronts for the reduction of violence and for the democratization of public safety in Brazil

Autonomous Obstacle Collision Avoidance System for UAVs in rescue operations

The Unmanned Aerial Vehicles (UAV) and its applications are growing for both civilian and military purposes. The operability of an UAV proved that some tasks and operations can be done easily and at a good cost-efficiency ratio. Nowadays, an UAV can perform autonomous tasks, by using waypoint mission navigation using a GPS sensor. These autonomous tasks are also called missions. It is very useful to certain UAV applications, such as meteorology, vigilance systems, agriculture, environment mapping and search and rescue operations. One of the biggest problems that an UAV faces is the possibility of collision with other objects in the flight area. This can cause damage to surrounding area structures, humans or the UAV itself. To avoid this, an algorithm was developed and implemented in order to prevent UAV collision with other objects. “Sense and Avoid” algorithm was developed as a system for UAVs to avoid objects in collision course. This algorithm uses a laser distance sensor called LiDAR (Light Detection and Ranging), to detect objects facing the UAV in mid-flights. This light sensor is connected to an on-board hardware, Pixhawk’s flight controller, which interfaces its communications with another hardware: Raspberry Pi. Communications between Ground Control Station or RC controller are made via Wi-Fi telemetry or Radio telemetry. “Sense and Avoid” algorithm has two different modes: “Brake” and “Avoid and Continue”. These modes operate in different controlling methods. “Brake” mode is used to prevent UAV collisions with objects when controlled by a human operator that is using a RC controller. “Avoid and Continue” mode works on UAV’s autonomous modes, avoiding collision with objects in sight and proceeding with the ongoing mission. In this dissertation, some tests were made in order to evaluate the “Sense and Avoid” algorithm’s overall performance. These tests were done in two different environments: A 3D simulated environment and a real outdoor environment. Both modes worked successfully on a simulated 3D environment, and “Brake” mode on a real outdoor, proving its concepts.Os veículos aéreos não tripulados (UAV) e as suas aplicações estão cada vez mais a ser utilizadas para fins civis e militares. A operacionalidade de um UAV provou que algumas tarefas e operações podem ser feitas facilmente e com uma boa relação de custo-benefício. Hoje em dia, um UAV pode executar tarefas autonomamente, usando navegação por waypoints e um sensor de GPS. Essas tarefas autónomas também são designadas de missões. As missões autónomas poderão ser usadas para diversos propósitos, tais como na meteorologia, sistemas de vigilância, agricultura, mapeamento de áreas e operações de busca e salvamento. Um dos maiores problemas que um UAV enfrenta é a possibilidade de colisão com outros objetos na área, podendo causar danos às estruturas envolventes, aos seres humanos ou ao próprio UAV. Para evitar tais ocorrências, foi desenvolvido e implementado um algoritmo para evitar a colisão de um UAV com outros objetos. O algoritmo "Sense and Avoid" foi desenvolvido como um sistema para UAVs de modo a evitar objetos em rota de colisão. Este algoritmo utiliza um sensor de distância a laser chamado LiDAR (Light Detection and Ranging), para detetar objetos que estão em frente do UAV. Este sensor é ligado a um hardware de bordo, a controladora de voo Pixhawk, que realiza as suas comunicações com outro hardware complementar: o Raspberry Pi. As comunicações entre a estação de controlo ou o operador de comando RC são feitas via telemetria Wi-Fi ou telemetria por rádio. O algoritmo "Sense and Avoid" tem dois modos diferentes: o modo "Brake" e modo "Avoid and Continue". Estes modos operam em diferentes métodos de controlo do UAV. O modo "Brake" é usado para evitar colisões com objetos quando controlado via controlador RC por um operador humano. O modo "Avoid and Continue" funciona nos modos de voo autónomos do UAV, evitando colisões com objetos à vista e prosseguindo com a missão em curso. Nesta dissertação, alguns testes foram realizados para avaliar o desempenho geral do algoritmo "Sense and Avoid". Estes testes foram realizados em dois ambientes diferentes: um ambiente de simulação em 3D e um ambiente ao ar livre. Ambos os modos obtiveram funcionaram com sucesso no ambiente de simulação 3D e o mode “Brake” no ambiente real, provando os seus conceitos

The Transport-Ticket System in Brazil for Urban Public Transport

The transport-ticket system in Brazil for urban public transport was implanted on 1987, in the big cities. By the system, the employers must to supply their employees with sufficient amount of tickets, to facilitate their diary translation from home to office. Since their implantation, the system facilitates the maintenance of the urban public transport quality and permits the normal fulfilment of the urban economic activity. Meanwhile, the system means a large allowance, from the firms and employers to the urban bus companies, partially compensated by the income tax depression. The article analyse just the effects, not properly beneficial, of this transport - ticket system functioning for the small and medium size firms.Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne

A simple thought experiment to discuss the mass–energy equivalence in the special theory of relativity

Einstein’s relation between mass and energy is perhaps the most famous equation of Physics. Despite its simplicity, the meaning of E0 = mc2 is not easy to grasp. Furthermore, its traditional derivations rely either on the integral of momentum, on properties of electromagnetic radiation, or even on the expression for transformation of energy. In the present work, we provide a simple thought experiment with an inelastic collision between two particles observed from two inertial reference frames. We show that for the conservation of relativistic momentum to hold, the mass of the system must increase after the collision. We also show that the increase of mass relates to the loss of kinetic energy according to the equation ∆K = −∆mc2 , which enables us to define the equation for relativistic energy (E = mc2/ p 1 − v 2/c 2 ), rest energy (E0 = mc2 ) and relativistic kinetic energy (K = E − E0). There are two main advantages in this presentation: first, it relies only on simple algebra, not depending on differential calculus and on any property of radiation; second, it leads directly to a comprehensible physical meaning of the relation of equivalence, which can sometimes be too obscure in more formal derivations

Special relativity from classical gedanken experiments involving electromagnetic forces : a contribution to relativity without light

Our goal is to present a derivation of Lorentz’s transformations from gedanken experiments with electromagnetic forces without having to assume Einstein’s postulate of the constancy of the speed of light. Instead, we propose a different second postulate, namely that electric charge is independent of the state of motion of the system, and we restrict the first postulate in order to state the relativity of electromagnetic forces only. We argue that assuming that charge is invariant is much more intuitive than assuming that light speed is constant. In this derivation, furthermore, the constancy of a limit speed c is obtained as a result of the velocity addition rule. Finally, we discuss the epistemological and didactic implications of this formulation

Bibliometric analysis of scientific production on sharing economy

Abstract Purpose – In recent years, much has been discussed about new consumer practices based on the sharing economy. In this context, the purpose of this paper is to map out the international scientific production on sharing economy. Design/methodology/approach – The research adopted a descriptive qualitative approach. Based on a sample of 95 documents collected in the Scopus database, analyses of bibliometric and sociometric indicators were carried out, as well as content analyses were conducted to identify the main thematic categories in the field. Findings – The results show that sharing economy is an emerging topic, and of late, the research in this field has grown rapidly. The study provides a mapping of top journals and authors, works of greatest impact and of co-authorship, co-citation and bibliographic coupling networks, which evidence the low intensity of researcher’s interactions and scientific production dispersion in the field. The main subjects found in the sharing economy literature are determinants, motivations and barriers, sharing economy impacts, regulation, models and frameworks, critical approach and entrepreneurship and sharing-based new businesses. Research limitations/implications – The analyses did not take into account the timing perspective. Further research could undertake a timeline-based approach in order to present direct citation networks and to relate works according to the year when they were published. Originality/value – The study innovates by identifying the main subjects in the sharing economy literature, as well as by presenting network analysis for some bibliometric indicators, complementing previous research in the field

Evolução e coexistência do serviço de mensagens SMS em IMS

De modo a conquistar a confiança e potenciar a aceitação e adesão dos utilizadores às Redes de Próxima Geração (RPG), é necessário garantir que os serviços mais populares das redes legadas (GSM/GPRS) continuam presentes. O Short Message Service (SMS) é um serviço de “dados”, extremamente rentável para as operadoras de telecomunicações, que permite a troca de mensagens curtas entre utilizadores de redes móveis, fixas e indirectamente também com utilizadores da internet. Como se revela essencial expandir este serviço para a RPG ou permitir a sua interacção com os novos serviços de mensagens, foi efectuado um estudo onde é abordada a coexistência do SMS e do serviço de Instant Messaging (IM) nas redes legadas e nas novas redes all-IP. Neste estudo, identificam-se as normas relevantes, os protocolos utilizados e seu funcionamento nos serviços de mensagens da rede IP Multimedia Subsystem (IMS), e a forma como podem ser utilizados para garantir a interoperabilidade com o SMS. Neste artigo apresenta-se o resultado do estudo efectuado, com o objectivo de facilitar a compreensão da solução para interoperabilidade proposta pelas entidades normalizadoras, clarificando os conceitos relacionados e facilitando, desta forma, o desenvolvimento de soluções de interoperabilidade entre serviços nas redes legadas e de próxima geração. Neste contexto, são descritos os serviços de mensagens da rede IMS e os componentes responsáveis por permitir a interoperabilidade com o SMS, em particular o seu módulo IP Short Message Gateway (IP-SM-GW)