X-38 Application of Dynamic Inversion Flight Control

This paper summarizes the application of a nonlinear dynamic inversion (DI) flight control system (FCS) to an autonomous flight test vehicle in NASA's X-38 Project, a predecessor to the International Space Station (ISS) Crew Return Vehicle (CRV). Honeywell's Multi-Application Control-H (MACH) is a parameterized FCS design architecture including both model-based DI rate-compensation and classical P+I command-tracking. MACH was adopted by X-38 in order to shorten the design cycle time for different vehicle shapes and flight envelopes and evolving aerodynamic databases. Specific design issues and analysis results are presented for the application of MACH to the 3rd free flight (FF3) of X-38 Vehicle 132 (V132). This B-52 drop test, occurring on March 30, 2000, represents the first flight test of MACH and one of the first few known applications of DI in the primary FCS of an autonomous flight test vehicle

Orion GN&C Detection and Mitigation of Parachute Pendulosity

New techniques being employed by Orion guidance, navigation, and control (GN&C) using a reaction control system (RCS) under parachutes are described. Pendulosity refers to a pendulum-oscillatory mode that can occur during descent under main parachutes and that has been observed during Orion parachute drop tests. The pendulum mode reduces the ability of GN&C to maneuver the suspended vehicle resulting in undesirable increases to structural loads at touchdown. Parachute redesign efforts have been unsuccessful in reducing the pendulous behavior necessitating GN&C mitigation options. An observer has been developed to estimate the pendulum motion as well as the underlying wind velocity vector. Using this knowledge, the control system maneuvers the vehicle using two separate strategies determined by wind velocity magnitude and pendulum energy thresholds; at high wind velocities the vehicle is aligned with the wind direction and for cases with lower wind velocities and large pendulum amplitudes the vehicle is aligned such that it is perpendicular to the swing plane. Pendulum damping techniques using RCS thrusters are discussed but have not been selected for use onboard the Orion spacecraft. The techniques discussed in this paper will be flown on Exploration Mission 1 (EM-1)

Orion GN&C Detection and Mitigation of Parachute Pendulosity

No abstract availabl

Orion GN&C Detection and Mitigation of Parachute Pendulosity

New techniques being employed by Orion guidance, navigation, and control (GN&C) using a reaction control system (RCS) under parachutes are described. Pendulosity refers to a pendulum-oscillatory mode that can occur during descent under main parachutes and that has been observed during Orion parachute drop tests. The pendulum mode reduces the ability of GN&C to maneuver the suspended vehicle resulting in undesirable increases to structural loads at touch-down. Parachute redesign efforts have been unsuccessful in reducing the pendulous behavior necessitating GN&C mitigation options. An observer has been developed to estimate the pendulum motion as well as the underlying wind velocity vector. Using this knowledge the control system maneuvers the vehicle using two separate strategies determined by a wind velocity magnitude threshold; at high wind velocities the vehicle is aligned with the wind direction and for cases with lower wind velocities the vehicle is aligned such that it is perpendicular to the swing plane. Pendulum damping techniques using RCS thrusters are discussed but have not been selected for use onboard the Orion spacecraft. The techniques discussed in this paper will be flown on Exploration Mission 1 (EM-1)

Protein Signaling Networks from Single Cell Fluctuations and Information Theory Profiling

Protein signaling networks among cells play critical roles in a host of pathophysiological processes, from inflammation to tumorigenesis. We report on an approach that integrates microfluidic cell handling, in situ protein secretion profiling, and information theory to determine an extracellular protein-signaling network and the role of perturbations. We assayed 12 proteins secreted from human macrophages that were subjected to lipopolysaccharide challenge, which emulates the macrophage-based innate immune responses against Gram-negative bacteria. We characterize the fluctuations in protein secretion of single cells, and of small cell colonies (n = 2, 3,···), as a function of colony size. Measuring the fluctuations permits a validation of the conditions required for the application of a quantitative version of the Le Chatelier's principle, as derived using information theory. This principle provides a quantitative prediction of the role of perturbations and allows a characterization of a protein-protein interaction network

Managing digital contention in China

This paper explores new developments in cyber content management strategies in China by highlighting the rise of participatory, peer-to-peer censoring practices, and examining how the People's Daily have responded to the contentious events in the top 20 public opinion incidents of 2016, to illustrate how official media uses different types of management strategies to mediate and demobilise contention, on top of information containment strategies such as censorship. I also discuss briefly the creation of a Digital United Front which seeks to incorporate social influencers and cyber elites into mainstream political institutions such as the CPPCC. Not only do these strategies further undermine the formation of a political locus opposite the state, they continue to subsume previously oppositional narratives into grander narratives of stability and national progress. Online political participation in Chinese cyberspace must seek further paternalistic protection from Party authorities in order to legitimise their contention. Although this strengthens the Party-state's claim to legitimacy, ultimately this weakens the emergence of civil society in China as the only form of contention that can survive is those that are legitimised by the Party-state, and the political space oppositional to the state remain closed off

Arterial-Venous Perfusion Without Anticoagulation: The Impeller Centrifugal Pump

A study was designed to test the effects of the absence of anticoagulation in the extracorporeal circuit. Five swine were subjected to this experiment utilizing the impeller centrifugal pump during which neither heparin nor any other anicoagulant was used. The extracorporeal circuit consisted of polyvinylchloride tubing, a Centri-Med®pump and an external stainless steel heat exchanger that was primed with albuminized Ringer's solution. An arterial-venous circuit was employed with oxygenation supplied from the subject's lungs. A series of blood aliquots were analyzed for coagulation at various times throughout the procedure. Following total body cooling using topically applied ice water, the subjects were rewarmed utilizing bypass. Within 10 minutes after the initiation of bypass, the circuits became clotted, rendering perfusion and subsequent warming ineffective. The lab values indicated that intrinsically activated coagulation occurred upon exposure to the extracorporeal apparatus. Flow visualization studies revealed a source of stagnant blood flow in the area around the hub of the pump head. Blood clot was similarly located in this area, with clot extension throughout the return circuit being realized. It is imperative that areas of stagnation be eliminated from extracorporeal circuits, since they may be potential sites for clot formation

Does Plasma Sequestration Reduce Post-Operative Bleeding?

Hematologic profiles, postoperative blood loss and transfusion requirements were studied in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) in order to determine the effect of sequestration and reinfusion of platelet-rich plasma (PRP). Eighteen patients were randomly selected to have approximately one unit of PRP collected or not prior to CPB. Autologous PRP was reinfused in nine patients after reversal of anticoagulation. Evaluation of results was based upon thrombocyte counts, Hgb, Hct, and platelet index readings pre- and post-PRP reinfusion, amount of blood loss and volumes of homologous blood and banked blood products required postoperatively. There were no hemodynamic complications related to the sequestration process. PRP reinfused patients had significantly higher thrombocyte counts after reversal of anticoagulation (p < 0.05). Patients receiving PRP required approximately 2/3 less banked blood products, their bleeding being significantly reduced 24 hours postoperatively (p < 0.05). We concluded that plasma sequestration and reinfusion of autologous PRP post-bypass may serve as an effective and safe way in decreasing blood loss after cardiac operations necessitating extracorporeal circulation

Personality Neuroscience: An Emerging Field With Bright Prospects

Personality neuroscience is the study of persistent psychological individual differences, typically in the general population, using neuroscientific methods. It has the potential to shed light on the neurobiological mechanisms underlying individual differences and their manifestation in ongoing behavior and experience. The field was inaugurated many decades ago, yet has only really gained momentum in the last two, as suitable technologies have become widely available. Personality neuroscience employs a broad range of methods, including molecular genetics, pharmacological assays or manipulations, electroencephalography, and various neuroimaging modalities, such as magnetic resonance imaging and positron emission tomography. Although exciting progress is being made in this young field, much remains unknown. In this brief review, we discuss discoveries that have been made, methodological challenges and advances, and important questions that remain to be answered. We also discuss best practices for personality neuroscience research and promising future directions for the field