Line-of-sight-stabilization and tracking control for inertial platforms

Nowadays, line of sight stabilization and tracking using inertially stabilized platforms (ISPs) are still challenging engineering problems. With a growing demand for high-precision applications, more involved control techniques are necessary to achieve better performance. In this work, kinematic and dynamic models for a three degrees-of-freedom ISP are presented. These models are based in the vehicle-manipulator system (VMS) framework for modeling of robot manipulators operating in a mobile base (vehicles). The dynamic model follows the Euler-Lagrange formulation and is implemented by numeric simulations using the iterative Newton-Euler method. Two distinct control strategies for both stabilization and tracking are proposed: (i) computed torque control and (ii) sliding mode control using the recent SuperTwisting Algorithm (STA) combined with a High-Order Sliding Mode Observer (HOSMO). Simulations using data from a simulated vessel allow us to compare the performance of the computed torque controllers with respect to the commonly used P-PI controller. Besides, the results obtained for the sliding mode controllers indicate that the Super-Twisting algorithm offers ideal robustness to the vehicle motion disturbances and also to parametric uncertainties, resulting in a stabilization precision of approximately 0,8 mrad.Hoje em dia, a estabilização e o rastreamento da linha de visada utilizando plataformas inerciais continuam a constituir desafiadores problemas de engenharia. Com a crescente demanda por aplicações de alta precisão, técnicas de controle complexas são necessárias para atingir melhor desempenho. Neste trabalho, modelos cinemáticos e dinâmicos para uma plataforma mecânica de estabilização inercial são apresentados. Tais modelos se baseiam no formalismo para sistemas veículo-manipulator para a modelagem de manipuladores robóticos operando em uma base móvel (veículo). O modelo dinâmico apresentado segue a formulação analítica de Euler-Lagrange e é implementado em simulações numéricas através do método iterativo de Newton-Euler. Duas estratégias de controle distintas para estabilização e rastreamento são propostas: (i) controle por torque-computado e (ii) controle por modos deslizantes utilizando o recente algoritmo Super-Twisting combinado com um observador baseado em modos deslizantes de alta ordem. Simulações utilizando dados de movimentação de um navio simulado permitem comparar o desempenho dos controladores por torque computado em relação a um tipo comum de controlador linear utilizado na literatura: o P-PI. Além disso, os resultados obtidos para o controle por modos deslizantes permitem concluir que o algoritmo Super-Twisting apresenta rejeição ideal a perturbações provenientes do movimento do veículo e também a incertezas paramétricas, resultando em precisão de estabilização de aproximadamente 0,8 mrad

Selling a Single Item with Negative Externalities

We consider the problem of regulating products with negative externalities to a third party that is neither the buyer nor the seller, but where both the buyer and seller can take steps to mitigate the externality. The motivating example to have in mind is the sale of Internet-of-Things (IoT) devices, many of which have historically been compromised for DDoS attacks that disrupted Internet-wide services such as Twitter. Neither the buyer (i.e., consumers) nor seller (i.e., IoT manufacturers) was known to suffer from the attack, but both have the power to expend effort to secure their devices. We consider a regulator who regulates payments (via fines if the device is compromised, or market prices directly), or the product directly via mandatory security requirements. Both regulations come at a cost---implementing security requirements increases production costs, and the existence of fines decreases consumers' values---thereby reducing the seller's profits. The focus of this paper is to understand the \emph{efficiency} of various regulatory policies. That is, policy A is more efficient than policy B if A more successfully minimizes negatives externalities, while both A and B reduce seller's profits equally. We develop a simple model to capture the impact of regulatory policies on a buyer's behavior. {In this model, we show that for \textit{homogeneous} markets---where the buyer's ability to follow security practices is always high or always low---the optimal (externality-minimizing for a given profit constraint) regulatory policy need regulate \emph{only} payments \emph{or} production.} In arbitrary markets, by contrast, we show that while the optimal policy may require regulating both aspects, there is always an approximately optimal policy which regulates just one

Proof-of-Stake Mining Games with Perfect Randomness

Proof-of-Stake blockchains based on a longest-chain consensus protocol are an attractive energy-friendly alternative to the Proof-of-Work paradigm. However, formal barriers to "getting the incentives right" were recently discovered, driven by the desire to use the blockchain itself as a source of pseudorandomness \cite{brown2019formal}. We consider instead a longest-chain Proof-of-Stake protocol with perfect, trusted, external randomness (e.g. a randomness beacon). We produce two main results. First, we show that a strategic miner can strictly outperform an honest miner with just $32.5\%$ of the total stake. Note that a miner of this size {\em cannot} outperform an honest miner in the Proof-of-Work model. This establishes that even with access to a perfect randomness beacon, incentives in Proof-of-Work and Proof-of-Stake longest-chain protocols are fundamentally different. Second, we prove that a strategic miner cannot outperform an honest miner with $30.8\%$ of the total stake. This means that, while not quite as secure as the Proof-of-Work regime, desirable incentive properties of Proof-of-Work longest-chain protocols can be approximately recovered via Proof-of-Stake with a perfect randomness beacon. The space of possible strategies in a Proof-of-Stake mining game is {\em significantly} richer than in a Proof-of-Work game. Our main technical contribution is a characterization of potentially optimal strategies for a strategic miner, and in particular, a proof that the corresponding infinite-state MDP admits an optimal strategy that is positive recurrent.Comment: 79 Pages, ACM EC 202

Credible Decentralized Exchange Design via Verifiable Sequencing Rules

Trading on decentralized exchanges has been one of the primary use cases for permissionless blockchains with daily trading volume exceeding billions of U.S.~dollars. In the status quo, users broadcast transactions and miners are responsible for composing a block of transactions and picking an execution ordering -- the order in which transactions execute in the exchange. Due to the lack of a regulatory framework, it is common to observe miners exploiting their privileged position by front-running transactions and obtaining risk-fee profits. In this work, we propose to modify the interaction between miners and users and initiate the study of {\em verifiable sequencing rules}. As in the status quo, miners can determine the content of a block; however, they commit to respecting a sequencing rule that constrains the execution ordering and is verifiable (there is a polynomial time algorithm that can verify if the execution ordering satisfies such constraints). Thus in the event a miner deviates from the sequencing rule, anyone can generate a proof of non-compliance. We ask if there are sequencing rules that limit price manipulation from miners in a two-token liquidity pool exchange. Our first result is an impossibility theorem: for any sequencing rule, there is an instance of user transactions where the miner can obtain non-zero risk-free profits. In light of this impossibility result, our main result is a verifiable sequencing rule that provides execution price guarantees for users. In particular, for any user transaction $A$, it ensures that either (1) the execution price of $A$ is at least as good as if $A$ was the only transaction in the block, or (2) the execution price of $A$ is worse than this ``standalone'' price and the miner does not gain (or lose) when including $A$ in the block.Comment: 32 Page

Systematic Review And Meta-analysis Of Target Terapies For The Treatment Of Metastatic Renal Cancer.

At present there are several drugs for the treatment of advanced renal cell carcinoma (ARCC). The main objective of this work was to perform a systematic review (SR) and meta-analysis (MA) of clinical randomized studies that compared target cell therapies (TCT). SR identified clinical randomized trials that compared TCT versus interferon-alpha in the treatment of patients with ARCC. In order to analyze efficiency, it was evaluated free-survival progression (FSP), total survival (TS) and response rate (RR). In relation to first line treatment, seven studies of TCT were identified using sunitinib, sorafenib, bevacizumab and temsirolimus; and two studies with sorafenib and everolimus for second line treatment. Relative risk (RRi) of MA for FSP of first line therapies was: 0.83, CI = 0.78-0.87, I2 = 94% and p < 0.00001. Best results of RR of specific FSP among studies were: 0.38, sunitinib, CI = 0.25-0.58, bevacizumab, 0.62, CI = 0.47-0.83; and temsirolimus, 0.78, CI = 0.70-0.87. MA didn't show any benefit regarding TS of first line treatment of all analyzed drugs. As for RR significant results were: sunitinib, 3.83 CI = 2.86-5.12; bevacizumab, 2.52 CI = 1.78-3.57 and bevacizumab, 1.97 CI = 1.43-2.71. For first line treatment, sunitinib was the most effective TCT in relation to FPS; there was no alteration of TS and RR was small but significant for sunitinib and bevacizumab. Available studies could not conclude any results for second line treatments.39768-7

Magnetic Resonance Image In The Diagnosis And Evaluation Of Extra-prostatic Extension And Involvement Of Seminal Vesicles Of Prostate Cancer: A Systematic Review Of Literature And Meta-analysis.

Systematic review of literature and meta-analysis to evaluate the results of magnetic resonance image 1.5T with endorectal coil in the diagnosis and evaluation of extra-prostatic extension and involvement of seminal vesicles of prostate cancer, compared to the histopathological results of the radical prostatectomy specimen. It was conducted a systematic review of literature and meta-analyses of all studies data published after 2008. In those studies, the patients with prostate cancer with indication to radical prostatectomy were submitted to magnetic resonance image (MRI) at pre-operatory period and the results were compared to those of histopathological studies after the surgery. The selected terms for research included prostate cancer, magnetic resonance, radical prostatectomy, and prostate cancer diagnosis, in the databases EMBASE, LILACS, PUBMED/MEDLINE and Cochrane Library. The data were collected using a specific qualitative instrument and the meta-analysis data were presented in the forest plot graphics, homogeneity test and sROC curves and funnel plot. A total of seven studies were included, with a total of 603 patients. Among these studies, six evaluated the value of MRI for the detection of prostate cancer, and the median sensitivity of meta-analysis was 0.6 and specificity 0.58, but with heterogeneity among the studies. Three studies evaluated extra-prostatic extension with a median sensitivity of 0.49, specificity 0.82 and heterogeneity only for sensitivity. Three studies evaluated invasion of seminal vesicles, with median sensitivity of 0.45 and specificity 0.96, with heterogeneity in both analysis. Magnetic resonance of 1.5T with endocoil showed low values of sensitivity and specificity for the diagnosis and staging of prostate cancer. The reviewed studies showed a significant heterogeneity among them. The best observed result was MRI specificity for invasion of seminal vesicles. More studies are necessary to evaluate new techniques and parameters before recommending the routine use of MRI in clinical practice.39215516

Rua da Juventude

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. ArquiteturaA problemática da educação brasileira não é recente, ela está diretamente relacionada às características da história social e econômica brasileira, com associação direta ao sistema atual empregnado do na sociedade, condições essas que colaboram para exclusão social e racial das classes populares. Essa problemática afeta principalmente as classes populares que por fim, se incorporam a marginalização, tendo uma conexão direta ao consumo excessivo de bens materiais instituído na sociedade atual. Isso faz com que os jovens queiram se incluir nesta parcela capitalista, sem apoios necessários, restando somente o dinheiro facilitado, incorporando-se ao mundo do crime. O sistema atual da violência urbana destaca pontos importantes responsáveis por essa problemática tão recorrente na sociedade atual e que engloba associações diretas ao capitalismo, sendo os que mais sofrem com tal violência são aqueles sujeitos em busca de um meio de vida digno mesmo diante da escassez do material. Hoje, no Brasil, a violência que se vive não vem do nada, ou de fatores desconhecidos, mas de motivos que são constantemente ignorados. Longe de ser um acidente na história nacional, a violência urbana tem tudo a ver com certas características históricas sociais e econômica brasileira, não podendo ser atribuída ingenuamente ou ideologicamente a perturbações intempestivas da consciência de alguns indivíduos, nem a uma repentina mudança das condições do país (PINO, 2007). A violência está em toda parte, em todo lugar e pode ser vista a qualquer momento em diversos lugares. Com o passar dos anos se tem falado apenas em desenvolver segurança à população, sem reconhecer que o problema da criminalidade é um fato histórico e social deste país. Com o afastamento da classe popular à educação e os privilégios de minorias dominantes, revela-se uma problemática recorrente associada às injustiças e situações de desvantagens sociais

Nos limites da história: os primeiros anos do IHGSC e as fronteiras de Santa Catarina

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Filosofia e Ciências Humanas. História.Este trabalho tentará então compreender quais eram as relações que haviam entre o governo do Estado de Santa Catarina e o Instituto Histórico e Geográfico de Santa Catarina e, caso exista, expor o vínculo entre estas duas entidades. Para isso, dividirei o trabalho em dois capítulos. No primeiro capítulo, “O surgimento do Instituto”, irei expor as demandas políticas, socioeconômicas e culturais que eram presentes e que possam ter influenciado a fundação do Instituto Histórico e Geográfico de Santa Catarina. Já no segundo – “Uma questão de fronteiras” - tratarei de demonstrar como os estudos promovidos pelo IHGSC estavam intimamente ligados às necessidades do Estado aproveitar melhor o território catarinense