Guidance, Navigation and Control System of a Hopper Spacecraft Simulator

The space hopper simulator project drew its origin from a partnership with Penn State University to compete in the Google Lunar XPRIZE competition. Lehigh University is tasked with the exploring the guidance, navigation and control (GN&C) system of the hopper spacecraft. To simulate the dynamics and flight behavior of the concept, Earth-based multirotor flying platforms were developed with the end goal of executing the hopping maneuver.The overall project has been ongoing for more than 5 years and went through several major revisions to fix flaws discovered in the previous design. As older students graduate and new teams are form, knowledge and experience are lost in the process. Due to the time it take to relearn and redesign the simulators, the project progress only get as far as achieving radio controlled flight. The current and 3rd generation development team aims to change that by developing both the hardware and software using modular design.With modular design, the manufacturing, repair and modification process for the multirotor speed up significantly. The damaged component can be replaced with little effort. In addition to the hardware advantages, the software modules enable concurrent development of both a PID and a Fuzzy Logic based flight control system using similar avionics and software architecture. Since the flight operating system function by linking the various software modules, individual modules can easily be swapped to test different control laws, electronic devices, etc. The software modules are also capable of being reused in other applications, such as running the thrust test stand and logging data with the wireless ground station.In theory and simulation, the GN&C system is quite simple. The hopping guidance trajectory can be generated by a set of linear and trigonometric equations. The trajectory can be optimized by minimizing the total energy consumption at the end of the hopping maneuver. The navigational data can be collected from the GPS and localized for the cascade PID controllers to achieve the desired trajectory. In the ideal world, everything is simple and easy.In the real world, a range of problems arise during implementation. Factors such as time delay and noises significantly impact the performance of the control system, making stable aggressive tuning very difficult to achieve. In an attempt to improve the condition, a number of digital filters such as the moving average filter and the Kalman filter were explored. In addition, every sub-system was analyzed in depth to optimize for speed. This resulted in 3 major revisions in changing flight computer and programming languages.Even though the main topic of this research is the guidance, navigation and control system, the project quickly expanded into a systems engineering problem. Everything must work well together in order for the aircraft to achieve stable flight

Cyber Security

This open access book constitutes the refereed proceedings of the 16th International Annual Conference on Cyber Security, CNCERT 2020, held in Beijing, China, in August 2020. The 17 papers presented were carefully reviewed and selected from 58 submissions. The papers are organized according to the following topical sections: access control; cryptography; denial-of-service attacks; hardware security implementation; intrusion/anomaly detection and malware mitigation; social network security and privacy; systems security

Designing topological quantum matter in and out of equilibrium

Recent advances in experimental condensed matter physics suggest a powerful new paradigm for the realization of exotic phases of quantum matter in the laboratory. Rather than conducting an exhaustive search for materials that realize these phases at low temperatures, it may be possible to design quantum systems that exhibit the desired properties. With the numerous advances made recently in the fields of cold atomic gases, superconducting qubits, trapped ions, and nitrogen-vacancy centers in diamond, it appears that we will soon have a host of platforms that can be used to put exotic theoretical predictions to the test. In this dissertation, I will highlight two ways in which theorists can interact productively with this fast-emerging field. First, there is a growing interest in driving quantum systems out of equilibrium in order to induce novel topological phases where they would otherwise never appear. In particular, systems driven by time-periodic perturbations—known as “Floquet systems”—offer fertile ground for theoretical investigation. This approach to designer quantum matter brings its own unique set of challenges. In particular, Floquet systems explicitly violate conservation of energy, providing no notion of a ground state. In the first part of my dissertation, I will present research that addresses this problem in two ways. First, I will present studies of open Floquet systems, where coupling to an external reservoir drives the system into a steady state at long times. Second, I will discuss examples of isolated quantum systems that exhibit signatures of topological properties in their finite-time dynamics. The second part of this dissertation presents another way in which theorists can benefit from the designer approach to quantum matter; in particular, one can design analytically tractable theories of exotic phases. I will present an exemplar of this philosophy in the form of coupled-wire constructions. In this approach, one builds a topological state of matter from the ground up by coupling together an array of one-dimensional quantum wires with local interactions. I will demonstrate the power of this technique by showing how to build both Abelian and non-Abelian topological phases in three dimensions by coupling together an array of quantum wires

Interrogation of Optical Fiber Sensors for Civil Engineering Applications using Widely Tunable Laser

Předložená disertační práce zkoumá možnosti použití nového typu polovodičového MGY- Laseru elektricky laditelného v širokém spektrálním rozsahu a zabývá se možnostmi jeho nasazení v optovláknové senzorové síti založené na metodě FBG (Fiber Bragg Grating). Výzkum byl započat komplexními dlouhodobými testy reálného měřícího scénáře z oblasti stavebnictví, sestaveného pro účely ověření limitujících aspektů současných technik. Inženýrské aplikace nabízejí velké množství vzájemně se vylučujících požadavků pro návrh strukturálních senzorových systémů. Tyto požadavky jsou sdíleny mnoha dalšími technologickými oblastmi, což přispívá k vysokému stupni univerzálnosti použití dosažených výsledků. Na základě posouzení stavu současné techniky a aplikačních požadavků byly v práci nejprve identifikovány aspekty, které mají být výzkumem zlepšeny. V dalším kroku byl detailně charakterizován MG-Y laser Syntune/Finisar S7500. Na základě dat získaných měřením byla zkoumána nová metoda spojitého řízená vlnové délky záření laseru. Provedené experimenty vedly nejen k návrhu nového způsobu spojité regulace vlnové délky ale také k vytvoření prostředků pro vlastní kalibraci systému na základě jeho vnitřních vlastností (podélných módů rezonátoru).This dissertation investigates the use of a MG-Y-Laser, a novel type of semiconductor laser that is electrically tunable over a wide spectral range, for the interrogation of Fiber Bragg Grating (FBG) based fiber-optical sensing networks. The research started with a complex long-term test of a real world measurement scenario from the field of civil engineering to elucidate limiting aspects of state of the art techniques. Civil engineering applications pose a multitude of mutually exclusive challenges toward structural sensing systems. These challenges are shared by many other fields of technology, making the results to a large degree universally applicable. Following an assessment of the state of art and the application requirements, the aspects to be improved by the research were identified. A Syntune/Finisar S7500 MG-Y-Laser device was then thoroughly characterized. Based on the gathered measurement data, novel tuning methods aimed at wavelength continuous control were investigated. This led to the invention of a tuning method that not only allows wavelength continuous control but also provides a means of self calibration based on intrinsic properties (longitudinal cavity modes) of the device.

Graph Theory and Universal Grammar

Tese arquivada ao abrigo da Portaria nº 227/2017 de 25 de Julho-Registo de Grau EstrangeiroIn the last few years, Noam Chomsky (1994; 1995; 2000; 2001) has gone quite far in the direction of simplifying syntax, including eliminating X-bar theory and the levels of D-structure and S-structure entirely, as well as reducing movement rules to a combination of the more primitive operations of Copy and Merge. What remain in the Minimalist Program are the operations Merge and Agree and the levels of LF (Logical Form) and PF (Phonological form). My doctoral thesis attempts to offer an economical theory of syntactic structure from a graph-theoretic point of view (cf. Diestel, 2005), with special emphases on the elimination of category and projection labels and the Inclusiveness Condition (Chomsky 1994). The major influences for the development of such a theory have been Chris Collins’ (2002) seminal paper “Eliminating labels”, John Bowers (2001) unpublished manuscript “Syntactic Relations” and the Cartographic Paradigm (see Belletti, Cinque and Rizzi’s volumes on OUP for a starting point regarding this paradigm). A syntactic structure will be regarded here as a graph consisting of the set of lexical items, the set of relations among them and nothing more