Control of a varying thrust spacecraft for autonomous space rendezvous

Before the use of autonomous rendezvous will be allowed as a substitute for man-in-the-loop control, adequate safety and mission performance will have to be guaranteed. Most autopilots for autonomous rendezvous of spacecraft assume constant thrust reaction control system (RCS) thrusters. This assumption implies either true constant thrust RCS thrusters or thrusters whose thrust levels vary very slowly. The ongoing work described in this presentation examines the autonomous rendezvous problem when varying thrust RCS thrusters are inherent in the system equations of motion

An experimental investigation of a fully cavitating two-dimensional flat plate hydrofoil near a free surface

An experimental program was conducted to investigate the characteristics of a fully cavitating two-dimensional flat plate hydrofoil in the presence of a free surface. The submergence of the hydrofoil was varied from the planing condition at the free surface to a depth corresponding to 2.16 model chords. Near the surface the cavities formed by venting to the atmosphere, but at the deeper submergences, they had to be artificially formed by supplying them with air. The normal force, the moment about the leading edge, the center of pressure location, the cavity length, and the volumetric air flow rate into the cavity are presented as functions of angle of attack, cavitation number, Froude number, and proximity to the free surface

Relation between intraventricular pressure and volume in diastole

The pressure-volume curves for 10 patients with various types of heart disease were studied throughout mid to late diastole when both pressure and volume were increasing. The results were used to test a currently held theory that the form of this relation is exponential. It was found that for the patients examined this hypothesis was not valid

Cyber warfare: threats and opportunities

Relatório apresentado à Universidade Fernando Pessoa como parte dos requisitos para o cumprimento do programa de Pós-Doutoramento em Ciências da InformaçãoCybersecurity has gone through several changes that have presented new challenges in recent years, complicated by the rise of cybercrime and digital warfare. With the introduction of militarizing the space domain, it has become apparent that we must consider multidomain concepts. Thus, the threat landscape has again shifted, and defenders must become knowledgeable about how the cyber domain crosses into maritime, land, air, and space. The traditional thinking of protecting enterprise systems locked away in a building is no longer. Thus, we have the emergence of cyber warfare and cyber as a fifth domain that brings together maritime, land, space, and air. These domains are not just for the military but the civilian sector as well. Understanding the role of cyber and how it can be used to take advantage or secure the remaining domains will give entities the upper hand in strategy. The technological advancements that pave the way to the mass implementation of the Internet of Things (IoT) and Internet connectivity to everyday devices have led to an explosion in cyberattacks such as breaches resulting in millions of accounts being compromised. (Dawson, Eltayeb, & Omar, 2016). Bad actors such as those focused on criminal activities regarding human trafficking and espionage navigate these domains to circumvent law enforcement agencies globally. We must understand how exploitation, circumvention, and defense needs to occur in a multidomain concept. However, knowing that the cyber domain is a domain that goes through land, maritime, space, and air can be an area that serves as a central point for realizing assured security. Executive Orders (EO), laws, policies, doctrine, and other directives have shaped the landscape of cybersecurity. New EOs have been released that allow a cyber-attack with responsive measures such as one that involves military force. Laws created that impose rights for Personal Identifiable Information (PII) being breached, leaving millions of individuals unprotected. One of these most well-known items is General Data Protection Regulation (GDPR) as it relates to the European Union (EU) and the evolving threats with hyperconnectivity (Martínez, 2019a; Martínez, 2019b). Understanding the role of cybercrime and digital warfare and how they continue to play in shaping the technological landscape is critical. These various actions change the spectrum regarding combating nefarious actors or design errors that leave the system susceptible. As attacks continue to rise from bad actors such as nation-states, terrorists, and other entities, it is essential to understand the threat landscape and select cybersecurity methodologies that can be put in place to provide adequate measures. This document presents the work form a post-doctoral project that provides a perspective of cybersecurity under a information science perspective. This six-month project allows to stress the broadly importance that information and its management (not just within the information security context), and the urgent need to deal with cybersecurity as a societal challenge. The document is organized in four main chapters presenting different but complementary issues, going from high level to a more operational level: National Cybersecurity Education: Bridging Defense to Offense, stressing the importance of societal awareness and education. Emerging Technologies in the Fourth Industrial Revolution, stressing the importance to consider cybersecurity issues as core ones, even to economic and production areas. Nefarious Activities within the Deep Layers of the Internet, stressing the need to be part of digital places where information is traded, shared and, even sometimes, created. The fourth chapter provide a few hints and issues related with software development and test: Software Security Considerations. A final session presents several remarks as Final Thoughts, closing the work pointing out some of the current challenges that we are facing of.N/

Participation in the police promotional process for the rank of sergeant within the Fairfax County Police Department Fairfax, Virginia

Police Departments across the country are experiencing vast numbers of veteran supervisory and command personnel retiring from public service. Without careful planning, these retirements can create a leadership void that will be difficult to fill with well-qualified candidates. These separations pose a loss of institutional knowledge, expertise and leadership continuity. The research conducted focused on the underlying reasons why highly-competent, experienced police officers are refusing to advance their law enforcement careers in becoming supervisors. The study included a review of the published literature and surveys being administered to 105 non-supervisory Fairfax County Police Officers on their interest in becoming a supervisor at the entry rank of sergeant. The fostering of future leaders should be made a priority and it should be the responsibility of those in leadership positions to identify, mentor and assist aspiring supervisory candidates to obtain the training and experience required to become a successful police manager

A comparison of physical measurements of pure-tones, third-octave bands of noise and third-octave bands of speech to subjective judgments of audibility threshold, MCL and UCL for three normally hearing listeners

This study investigates the relation between physical measurements of pure-tones, third-octave bands of noise and third-octave bands of speech and subjective judgments of auditory threshold, most-comfortable listening level (MCL) and uncomfortable-listening level (UCL) for three normally hearing listeners

Information requirements for guidance and control systems

Control or guidance system performance dependency on information handling by subsystem