Aerospace medicine and biology: A continuing bibliography with indexes (supplement 375)

This bibliography lists 212 reports, articles, and other documents recently introduced into the NASA Scientific and Technical Information System database. Subject coverage includes the following: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance

Evolution of the SpaceLiner towards a Reusable TSTO-Launcher

Since a couple of years the DLR launcher systems analysis division is investigating a visionary and extremely fast passenger transportation concept based on rocket propulsion. The fully reusable concept consists of two vertically launched winged stages in parallel arrangement. The space transportation role of the SpaceLiner concept as a TSTO-launcher is now, for the first time, addressed in technical detail. Different mission options to LEO and beyond are traded and necessary modifications of the passenger stage to an unmanned cargo-carrier are investigated and described in this paper. Meanwhile, technical progress of the SpaceLiner ultra-high-speed passenger transport is ongoing at Phase A conceptual design level. Iterative sizings of all major subcomponents in nominal and off-nominal flight conditions have been performed. Potential intercontinental flight routes, taking into account range-safety and sonic boom constraints as well as good reachability from major business centers, are evaluated and flight guidance schemes are established. Alternative passenger cabin and rescue capsule options with innovative morphing shapes were also investigated. The operational and business concept of the SpaceLiner is under definition. The project is on a structured development path and as one key initial step the Mission Requirements Review has been successfully concluded

Preparatory studies of zero-g cloud drop coalescence experiment

Experiments to be performed in a weightless environment in order to study collision and coalescence processes of cloud droplets are described. Rain formation in warm clouds, formation of larger cloud drops, ice and water collision processes, and precipitation in supercooled clouds are among the topics covered

The value of revenue management innovation in a competitive airline industry

May 1995Includes bibliographical references (p. 129-130)The value of revenue management to the airlines has been amply demonstrated, both by industry experience and in simulation studies of the reservation process. However, there have been no attempts to determine if the benefits of seat inventory control are specific to the competitive market setting in which it is instituted. Furthermore, previous theoretical research has not considered whether interactions of the control methods of rival carriers may affect both the total revenue improvement attainable in the market and how these gains are shared by individual carriers. This thesis uses a modeling approach created by the Boeing Commercial Airplane Group to address these questions. The Passenger Origin / Destination Simulator combines a demand model framework with a set of routines which implement the basic forecasting and inventory control functions of airline revenue management. The Boeing simulation system is implemented in the thesis through the development of a generic fare product structure, passenger behavioral attributes, and assumptions on demand composition. Within this Operational Competitive Simulation Environment, the effect of competition on the value of revenue management is explored in simulation experiments with three classes of scenarios. In these scenarios, the gains from leg-based inventory control are assessed under varying competitive conditions, including the magnitude and distribution of passenger demand, carrier frequency share, relative departure timing, and route network design. From the simulation results, it is apparent first that inventory control innovation always improves carrier and aggregate market revenues-competition along the dimension of revenue management is not a zero-sum game from the carriers' perspective. A signal contribution of the experimental research has been the finding that the revenue dividend from inventory control derives largely from the sale of higher-yield fare products to leisure and discretionary business passengers, and only marginally at the expense of those carriers with a less advanced control capability. Additionally, the relative changes in revenue due to different control methods are indeed influenced by other competitive forces operative in the market

Design and Optimisation of a Virtual Prototype of a Ground Transportation System at Very High-Speeds in Conditions Close to Vacuum

[ES] Hyperloop es considerado el quinto medio de transporte, después del coche, barco, tren y avión. Consiste en una capsula de levitación magnética que viaja dentro de un tubo en el que la presión de aire ha sido reducida. Entonces, la fricción con el suelo y resistencia aerodinámica son minimizadas, alcanzando ultra altas velocidades a nivel de tierra. Actualmente hay en desarrollo varios trenes maglev y conceptos hyperloop. La mayoría proponen levitar usando Suspensión Electromagnética (EMS). Zeleros, la compañía donde esta Tesis ha sido realizada, tiene una propuesta similar. Zeleros usa un EMS Híbrido (HEMS), combinando imanes y electroimanes para reducir los requerimientos de energía. Respecto a la propulsión, la propuesta es única ya que hace uso de un compresor de la industria aeroespacial. Simulaciones CFD prueban que usar un compresor reduce considerablemente la resistencia aerodinámica en el ambiente cerrado, ya que el efecto pistón es mitigado. Para el mismo tamaño de tubo y presión, un hyperloop con compresor requiere hasta 70 % menos potencia. En otros términos, si la misma potencia es instalada en el vehículo, el diámetro de la infraestructura puede ser 2.8 veces más pequeño. Esta Tesis desarrolla un simulador 0D para evaluar el rendimiento de la solución hyperloop propuesta. Resolver su aerodinámica requiere solucionar un fujo interno y externo de Fanno. El último combina efectos de Couette y Poisuille en un dominio anular. Así, se desarrolla un modelo simplificado para flujos de Fanno, acelerando así el modelado básico. Esta aproximación matemática incluye información de la velocidad de la pared y de la forma del dominio, evitando integrar un sistema de EDOs. La solución tiene una desviación en la ratio de presiones de 5 % respecto a CFD, y del 10 % en la longitud crítica. El simulador modela toda la termodinámica del vehículo, incluyendo el compresor, conductos, turbina, tobera y flujo externo. Este modelado es similar al del ciclo de Bryton, sin cámara de combustión. Además, se incluye un modelo para predecir la masa y longitud de la cápsula y sus componentes. Así, las pérdidas de fricción y requerimientos de potencia y energía son obtenidos. Estos resultados presentan una desviación máxima del 20 % respecto a CFD. Además, un proceso de optimización para encontrar la solución más eficiente se ha desarrollado con el código, para vehículos de 50 y 150 pasajeros. Se ha encontrado que es más beneficioso absorber menos gasto másico con el compresor, ya que la energía requerida para comprimir el flujo interno es más alta que las pérdidas en el canal externo. Comparando el consumo de energía específico de esta solución con otros medios de transporte, el hyperloop se encuentra cercano al rendimiento de los maglev. Éste es, también, entre tres y cinco veces más eficiente que los aviones. Además, es más competitivo que el avión en términos de velocidad media en una ruta hasta los 800 km. Por último, se desarrolla un modelo similar para un sistema de escala media. Este prototipo, cuya velocidad objetivo es de 500 km/h, es diseñado por Zeleros previo al sistema de escala real. Su simulador incluye además los efectos transitorios y la termodinámica del tubo, asumiendo una velocidad del sonido infinita. Gracias a este código, se puede obtener el rendimiento en una misión. Inicialmente, el prototipo incrementa la presión del tubo aguas arriba, y la reduce aguas abajo debido al efecto pistón, generando una velocidad inducida. Al final de la misión, el flujo puede ser transferido otra vez, y las presiones se equilibran otra vez. Este modelo también predice el par y potencia del motor eléctrico, además de los parámetros de la batería (voltaje, corriente y profundidad de descarga).[CA] Hyperloop és considerat el cinquè mitjà de transport, després del cotxe, vaixell, tren i avió. Consisteix en una càpsula de levitació magnètica que viatja dins d'un tub on la pressió d'aire es reduïda. Aleshores, la fricció amb el sòl i resistència aerodinàmica són minimitzades, aconseguint ultra altes velocitats a nivell de terra. Actualment hi ha en desenvolupament diversos trens maglev i conceptes hyperloop. La majoria proposen levitar usant Suspensió Electromagnètica (EMS). Zeleros, la companyia on aquesta Tesi ha sigut realitzada, té una proposta similar. En particular, el concepte de Zeleros utilitza un EMS Híbrid (HEMS), combinant imants i electroimants per reduir els requeriments d'energia. Pel que fa a la propulsió, la proposta és única, ja que fa ús d'un compressor de la indústria aeroespacial. Simulacions CFD proven que utilitzar un compressor redueix considerablement la resistència aerodinàmica en un ambient tancat, ja que l'efecte pistó és mitigat. Per a la mateixa grandària de tub i pressió, un hyperloop amb compressor requereix fins a 70 % menys potència. En altres termes, si la mateixa potència és instal·lada al vehicle, el diàmetre de la infraestructura pot ser 2.8 vegades més menut. Aquesta Tesi desenvolupa un simulador 0D per avaluar el rendiment de la solució hyperloop proposada. Resoldre l'aerodinàmica del hyperloop requereix solucionar un flux intern i extern de Fanno. L'últim combina efectes de Couette i Poiseuille en un domini anular. Així, es desenvolupa un model simplificat per a fluxos de Fanno, accelerant així el modelatge bàsic. Aquesta aproximació matemàtica inclou informació de la velocitat de la paret i de la forma del domini, evitant integrar un sistema de EDOs. La solució té una desviació a la ràtio de pressions de 5 % respecte a CFD, i del 10 % a la longitud crítica. El simulador modela tota la termodinàmica del vehicle, incloent-hi el compressor, conductes, turbina, tovera i flux extern. Aquest modelat es similar al del cicle de Bryton, sense càmera de combustió. A més, s'inclou un model per predir la massa i la longitud de la càpsula i els seus components. Així, les pèrdues de fricció i requeriments de potència i energia són obtinguts. Aquests resultats presenten una desviació màxima del 20 % comparat amb CFD. A més, un procés d'optimització per trobar la solució més eficient ha estat desenvolupat amb el codi, per a vehicles de 50 i 150 passatgers. S'ha trobat que és més beneficiós absorbir menys massa amb el compressor, ja que l'energia requerida per comprimir el flux intern és més alta que les pèrdues al canal extern. Comparant el consum d'energia específic d'aquesta solució amb altres mitjans de transport, el hyperloop és proper al rendiment dels maglev. Aquest també és entre tres i cinc vegades més eficient que els avions. A més, és més competitiu en termes de velocitat mitjana en una ruta fins a 800 km. Finalment, es desenvolupa un model semblant per a un sistema d'escala mitjana. Aquest prototip, la velocitat objectiu del qual és de 500 km/h, és dissenyat per Zeleros previ al sistema d'escala real. El seu simulador inclou a més els efectes transitoris i la termodinàmica del tub, assumint una velocitat del so infinita. Gràcies a aquest codi, es pot obtenir el rendiment en una missió. Inicialment, el prototip incrementa la pressió del tub aigües amunt, i la redueix aigües avall degut a l'efecte pistó, generant una velocitat induïda. Al final de la missió, el flux pot ser transferit una altra vegada, i les pressions s'equilibren una altra vegada. Aquest model també prediu el parell i potència del motor elèctric, a més dels paràmetres de la bateria (voltatge, corrent i profunditat de descàrrega).[EN] Hyperloop is considered the fifth means of transportation, after the car, boat, train and plane. It consists of a magnetically levitating capsule that travels within a tube in which the air pressure has been reduced. Thus, the ground friction and aerodynamic drag are minimised, reaching ultra high-speeds at ground level. Several maglev trains and hyperloop concepts being developed currently. Most of them propose levitating using Electromagnetic Suspension (EMS). Zeleros, the company where this Thesis was done, has a similar approach. It employs a Hybrid EMS (HEMS)In particular, the Zeleros approach employs a Hybrid EMS (HEMS), combining permanent and electromagnets to reduce energy requirements. As for the propulsion, the approach is unique as it uses a compressor from the aeronautical industry. CFD simulations prove that using a compressor considerably reduces the aerodynamic drag in the closed environment, as the piston effect gets mitigated. For the same tube size and pressure, a hyperloop with compressor requires up to 70 % less power. In other terms, if the same power is installed on the vehicle, the infrastructure diameter can be 2.8 times smaller. This Thesis develops a 0D simulator to evaluate the performance of the proposed hyperloop solution. Solving the aerodynamics of the hyperloop requires solving internal and external Fanno flows. For the latter, the flow combines Couette and Poiseuille effects in an annular domain. Thus, a simplified model for Fanno flows is developed to accelerate the basic modelling. This mathematical approach includes the information of the wall speed and the shape of the domain, avoiding integrating an ODE system. The solution has a deviation in the pressure ratio of 5 % and 10 % in the critical length regarding CFD. The simulator models all the vehicle thermodynamics, including the compressor, duct, turbine, nozzle, and external flow. This modelling is similar to a Bryton cycle, without a combustion chamber. Also, a model to predict the mass and length of the capsule and its components is included. Thus, the friction losses and the energy and power requirements can be extracted. These outputs are compared with CFD results, with a maximum deviation of 20 %. Moreover, an optimisation process is conducted with the code to find the most efficient solution for 50- and 150-passenger vehicles. It is found that shallowing less mass flow with the compressor is better, as the energy required to compress the internal flow is higher than the losses on the external channel. Comparing the specific energy consumption of this solution with other means of transportation, the hyperloop is close to the maglev performance. It is also between three and five times more efficient than aeroplanes. Furthermore, the hyperloop is more competitive than the plane in terms of average speed on a route, up to 800 km. The last part of this work develops a similar model for a middle-scale system. This prototype, which aims to reach 500 km/h, is being designed by Zeleros before the real-scale one. Its simulator also includes the transient effects and the tube thermodynamics, assuming an infinite sound speed. Thanks to this code, the performance in a mission is obtained. The prototype initially increases the upstream tube pressure and reduces the downstream one due to the piston effect, generating an induced speed. At the end of the mission, the flow can be transferred again, and the pressures equilibrate again. This model also predicts the electric motor torque and power and the battery parameters (voltage, current, and deep of discharge).Este trabajo ha recibido una subvención parcial del Ministerio de Ciencia, Innovación y Universidades bajo la ayuda “Doctorandos Industriales” número DI-17-09616.Lluesma Rodríguez, F. (2022). Design and Optimisation of a Virtual Prototype of a Ground Transportation System at Very High-Speeds in Conditions Close to Vacuum [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19140

PEDAGOGY OF VIDEO-GAME SCORING FOR COLLEGIATE APPLICATION AND AN ORIGINAL SCORE FOR THE NINTENDO SWITCH TITLE, RENAINE

Video-game scoring as an academic subject is quite new. There are limited opportunities for college-level students to study this field, and even fewer that are offered remotely via online sources. My goal for this thesis was to craft educational modules, courses, or other academically-based resources, that would develop a student’s musical skills, professional instincts, and educational groundings in the game audio world. These courses could then serve as an academic model for the development of other classes. After conducting research informed by my professional background as a composer in the video game industry (with a particular focus on my experiences as a composer on the at-the-time in-development Nintendo Switch title Renaine), three courses were crafted and offered in back-to-back semesters. A group of test students participated in these three courses, and the response was exceptionally positive. This thesis collects the content produced for these courses, as well as my conclusions reached in association with them. It also includes original composition material produced for Renaine, including both final audio files and visual aids

F/A-18A-D Flight Control Computer OFP Versions 10.6.1 and 10.7 Developmental Flight Testing: Out-of-Controlled Flight Test Program Yields Reduced Falling Leaf Departure Susceptibility and Enhanced Aircraft Maneuverability

This thesis analyzes the recent Version 10.7 Operational Flight Program (v10.7 OFP) Flight Control System upgrade to the F/A-18A-D (legacy) Hornet fighter aircraft. This developmental program endeavored to improve high angle-of-attack (AOA) maneuverability while vastly reducing the aircraft’s susceptibility to sustained out-of- controlled flight events. Although the original F/A-18 Hornet, designated F/A-18A through F/A-18D, has been acclaimed for its departure resistance as well as its exceptional maneuverability as a fighter aircraft, the model, in actuality, has suffered from significant losses due to out-of- controlled flight (OCF) mishaps. Since its development in the early 1980s, eighteen Hornets have been lost to a particular OCF mode called “Falling Leaf”, including eight aircraft crashed since 1999. With no improvements, 10 additional aircraft, at a cost of $40 million each, were forecast to be lost. Two-seat aircraft are lost at a higher rate per flight hour than the more common single-seat version. Analysis of flight test data indicates that more two-seat aircraft sustain Falling Leaf mode due to their increased departure susceptibility. Additionally, it is apparent that the increased sprung mass of the control system, due to the addition of the rear cockpit control stick, may delay or inhibit recovery from a sustained Falling Leaf departure. This may be caused by uncommanded Flight Control System inputs from lateral control stick inertial motion induced by high sideforces encountered during a Falling Leaf. The v10.7 OFP test effort conducted a complete out-of-control flight test program without the benefit of having an attached spin-recovery parachute during testing. The specific test method and risk mitigation techniques used during this test program are reviewed and documented in this thesis to provide a historical record for future testing. By using the lessons learned from the development of the F/A-18E/F Super Hornet testing conducted a few years earlier, the v10.7 Team was able to complete the test at a large cost and schedule savings. The author concludes that the test program is an exceptional success. The new low airspeed and high AOA maneuvering capabilities inherent with the v10.7 software revolutionize how pilot aircrew will fight the aircraft. Further, the extremely enhanced resistance to sustained departure modes during out-of-controlled flight events will substantially reduce the frequency of aircraft mishaps and the associated loss of training and assets

Schrieffer-Wolff transformation for quantum many-body systems

The Schrieffer-Wolff (SW) method is a version of degenerate perturbation theory in which the low-energy effective Hamiltonian H_{eff} is obtained from the exact Hamiltonian by a unitary transformation decoupling the low-energy and high-energy subspaces. We give a self-contained summary of the SW method with a focus on rigorous results. We begin with an exact definition of the SW transformation in terms of the so-called direct rotation between linear subspaces. From this we obtain elementary proofs of several important properties of H_{eff} such as the linked cluster theorem. We then study the perturbative version of the SW transformation obtained from a Taylor series representation of the direct rotation. Our perturbative approach provides a systematic diagram technique for computing high-order corrections to H_{eff}. We then specialize the SW method to quantum spin lattices with short-range interactions. We establish unitary equivalence between effective low-energy Hamiltonians obtained using two different versions of the SW method studied in the literature. Finally, we derive an upper bound on the precision up to which the ground state energy of the n-th order effective Hamiltonian approximates the exact ground state energy.Comment: 47 pages, 3 figure

Airline revenue management performance measurement of South African Airways origin-destination revenue management

Revenue Management (RM) in the airline industry is the practise of selling fixed capacity as a service over a finite time horizon. The market is characterised by the customers’ willingness to pay different prices for the service. This creates the opportunity to target different customer segments and use price differential to attain the optimal passenger fare mix to maximise revenue. The aim is to maximise revenue and an airline can expect revenue increase of between 3 to 7 percent with the successful implementation of a Revenue Management system. The question of whether the revenue increase can be attributed to the RMS is crucial in determining its level of success and validating the optimisation strategy applied (Rannou and Melli, 2003). South African Airways (SAA) migration from Leg-based optimisation to Origin-Destination (O&D) network based revenue management optimisation created the opportunity for this study to measure and evaluate the RMS performance. Revenue performance measuring tools using inventory systems data to measure RMS performance, ASK (Available Seat Kilometre), RASK (Revenue per Available Seat Kilometre), CASK (Cost per Available Seat Kilometre), RPK (Revenue Passenger Kilometre) and cabin factor yield. The limitations relating to the performance measuring tools utilising inventory system data, is the inability for continuous measurement and the isolation of the impact to revenue due to the RMS on its own. In seeking to gauge the performance of the O&D optimisation, the Revenue Opportunity Model (ROM) is applied. ROM is a post departure measuring tool utilised to continuously measure and isolate the contribution of the RMS on SAA’s O&D network. The revenue opportunity achieved versus the potential revenue was assessed. A revenue comparison of the airlines 2014 and 2015 financial year is performed. The results of the analysis showed the O&D optimisation yielded positive revenue capture on routes that applied the correct optimisation strategy. Recommendations on the optimisation strategy to be applied on routes having average or low revenues captured are presented. The aim is to provide the SAA revenue management department with tangible solutions that would result in increased revenue for the SAA network