PRACTICAL SUPERSTITIONS: FENG SHUI IN ARCHITECTURE

China has experienced rapid growth and as China grows, so does its global influence. Chinese culture can be seen in countries all over the world, and its influence is evident in various cuisines, languages, and even architecture. However, despite the global trend towards a more modern style, there are various elements present in Chinese architecture that allow it to stand out from the rest. Various real-life structures embody key beliefs of Feng Shui, which is both a theory and a practice for connecting the mind, body, and spirit to one’s space or environment, anchored on the traditional Chinese worldview on the art of spatial alignment and orientation, and its relationship with humans and their environment. These architectural designs do not merely stem from cultural or ideological bases alone; they have practical, economical, and logical applications as well. These real-life examples highlight the practicality behind the practice of Feng Shui in architecture

A quantitative real options method for aviation technology decision-making in the presence of uncertainty

The developments of new technologies for commercial aviation involve significant risk for technologists as these programs are often driven by fixed assumptions regarding future airline needs, while being subject to many uncertainties at the technical and market levels. To prioritize these developments, technologists must assess their economic viability even though standard methods used for capital budgeting are not well suited to handle the overwhelming uncertainty surrounding such developments. This research proposes a framework featuring real options to overcome this challenge. It is motivated by three observations: disregarding the value of managerial flexibility undervalues long-term research and development (R&D) programs; windows of opportunities emerge and disappear and manufacturers can derive significant value by exploiting their upside potential; integrating competitive aspects early in the design ensures that development programs are robust with respect to moves by the competition. Real options analyses have been proposed to address some of these points but the adoption has been slow, hindered by constraining frameworks. A panel of academics and practitioners has identified a set of requirements, known as the Georgetown Challenge, that real options analyses must meet to get more traction amongst practitioners in the industry. In a bid to meet some of these requirements, this research proposes a novel methodology, cross-fertilizing techniques from financial engineering, actuarial sciences, and statistics to evaluate and study the timing of technology developments under uncertainty. It aims at substantiating decision making for R&D while having a wider domain of application and an improved ability to handle a complex reality compared to more traditional approaches. The method named FLexible AViation Investment Analysis (FLAVIA) uses first Monte Carlo techniques to simulate the evolution of uncertainties driving the value of technology developments. A non-parametric Esscher transform is then applied to perform a change of probability measure to express these evolutions under the equivalent martingale measure. A bootstrap technique is suggested next to construct new non-weighted evolutions of the technology development value under the new measure. A regression-based technique is finally used to analyze the technology development program and to discover trigger boundaries which help define when the technology development program should be launched. Verification of the method is performed on several canonical examples and indicates good accuracy and competitive execution time. It is applied next to the analysis of a performance improvement package (PIP) development using the Integrated Cost And Revenue Estimation method (i-CARE) developed as part of this research. The PIP can be retrofitted to currently operating turbofan engines in order to mitigate the impact of the aging process on their operating costs. The PIP is subject to market uncertainties, such as the evolution of jet-fuel prices and the possible taxation of carbon emissions. The profitability of the PIP development is investigated and the value of managerial flexibility and timing flexibility are highlighted.The developments of new technologies for commercial aviation involve significant risk for technologists as these programs are often driven by fixed assumptions regarding future airline needs, while being subject to many uncertainties at the technical and market levels. To prioritize these developments, technologists must assess their economic viability even though standard methods used for capital budgeting are not well suited to handle the overwhelming uncertainty surrounding such developments. This research proposes a framework featuring real options to overcome this challenge. It is motivated by three observations: disregarding the value of managerial flexibility undervalues long-term research and development (R&D) programs; windows of opportunities emerge and disappear and manufacturers can derive significant value by exploiting their upside potential; integrating competitive aspects early in the design ensures that development programs are robust with respect to moves by the competition. Real options analyses have been proposed to address some of these points but the adoption has been slow, hindered by constraining frameworks. A panel of academics and practitioners has identified a set of requirements, known as the Georgetown Challenge, that real options analyses must meet to get more traction amongst practitioners in the industry. In a bid to meet some of these requirements, this research proposes a novel methodology, cross-fertilizing techniques from financial engineering, actuarial sciences, and statistics to evaluate and study the timing of technology developments under uncertainty. It aims at substantiating decision making for R&D while having a wider domain of application and an improved ability to handle a complex reality compared to more traditional approaches. The method named FLexible AViation Investment Analysis (FLAVIA) uses first Monte Carlo techniques to simulate the evolution of uncertainties driving the value of technology developments. A non-parametric Esscher transform is then applied to perform a change of probability measure to express these evolutions under the equivalent martingale measure. A bootstrap technique is suggested next to construct new non-weighted evolutions of the technology development value under the new measure. A regression-based technique is finally used to analyze the technology development program and to discover trigger boundaries which help define when the technology development program should be launched. Verification of the method is performed on several canonical examples and indicates good accuracy and competitive execution time. It is applied next to the analysis of a performance improvement package (PIP) development using the Integrated Cost And Revenue Estimation method (i-CARE) developed as part of this research. The PIP can be retrofitted to currently operating turbofan engines in order to mitigate the impact of the aging process on their operating costs. The PIP is subject to market uncertainties, such as the evolution of jet-fuel prices and the possible taxation of carbon emissions. The profitability of the PIP development is investigated and the value of managerial flexibility and timing flexibility are highlighted.Ph.D

Optimal Trajectory and En-Route Contingency Planning for Urban Air Mobility Considering Battery Energy Levels

Copyright © 2022 by Seulki Kim, Caleb Harris, Cedric Y. Justin, and Dimitri Mavris . Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.Presented at the AIAA Aviation Forum, June 27-July 1, 2022, Chicago, IL & VirtualUrban Air Mobility (UAM) is an electric propelled, vertical takeoff and landing (eVTOL) aircraft envisioned for transporting passengers and goods within metropolitan areas. Planning UAM flights will not be easy as unexpected wind turbulence from high-altitude structures may impact the vehicles operating at a low altitude. Furthermore, considering the short travel time of the UAM, smart and safe decision-making will be challenging, particularly in off-nominal situations that force the aircraft to divert to an alternate destination instead of landing at the initially planned destination. To overcome these challenges, this research proposes automated pre-flight and in-flight contingency planning systems to assist in both normal and irregular UAM operations. A planner in the pre-flight planning system optimizes an aerial trajectory between the scheduled origin and destination, avoiding restricted high-level structures and estimating energy levels. In the contingency planning system, an in-flight replanner produces several optimal trajectories from where the diversion is declared to each alternate destination candidate. A diversion decision-making tool then scores a list of candidates and selects the best site for diversion. Real-world operational scenarios in the city of Miami are presented to demonstrate the capability of the proposed framework

Modeling Framework for Identification and Analysis of Key Metrics for Trajectory Energy Management of Electric Aircraft

Presented at AIAA AVIATION Forum, August 2-6, 2021, VIRTUAL EVENTTo prepare for the upcoming entry into service of electric and hybrid-electric aircraft, regulators may have to update or develop new regulations and standards to ensure safe operations of these new vehicles. To ensure public acceptance, these vehicles need to demonstrate an equivalent level of safety consistent with existing regulations. However, the ability to fly in different modes (forward flight, vertical flight) and the different powertrain elements may require significant changes to regulations to ensure that an insightful representation of the usable energy is provided to flight crews. This requires an understanding of the major operational differences between conventional and electric aircraft, and how these differences impact the trajectories a vehicle can fly. For instance, there is no simple analog to fuel gauges for measuring the extractable energy available on board electric aircraft, as energy related metrics can vary with a range of variables, such as component temperatures, battery health, and environmental conditions. It is thus more complex for flight crews to gauge in real-time how much usable energy is available and to figure out which trajectories are feasible with respect to both energy and power. To assess the feasibility of trajectories and quantify the adequacy of novel energy tracking metrics and methodologies, a trajectory energy management simulation environment is implemented allowing the simulation of various energy metrics across a range of vehicles and missions. This allows decision makers and regulators to assess the importance of these metrics for safe operation across a wide variety of missions. The impact of ambient air temperature, battery state of health, and initial battery, motor, and inverter temperatures are assessed for a typical flight mission. It is concluded that state of health, ambient temperature, and initial battery temperature all had significant impacts on the final state of charge and amount of extractable energy. Additionally, at high ambient temperatures and in aggressive climbs, motor temperature limits and inverter temperature limits can sometimes be reached, further complicating the assessment of what can be done with the amount of energy stored on board. Proper management of these constraints is therefore crucial for optimizing trajectories with respect to energy metrics. Future work is proposed regarding further expansion of the framework simulating aircraft with vertical takeoff and landing capability, and flight-dynamics algorithms that will enable simulation of optimal energy mission profiles

Development of a Simulation Environment to Track Key Metrics to Support Trajectory Energy Management of Electric Aircraft

Presented at AIAA AVIATION 2022 Forum, June 27-July 1, 2022, Chicago, IL & VirtualGrowing concerns worldwide about anthropogenic climate change are leading to significant research in ways to reduce greenhouse gas emissions. Technologies are investigated to improve the overall energy efficiency of flying vehicles, and among these, new powertrain technologies less reliant on fossil fuels are especially promising. Concurrently, the expected growth of new market segments, such as urban air mobility and regional air mobility where vehicles are envisioned to operate over densely populated areas, will lead to increased scrutiny regarding the vehicle emissions and the vehicle safety. In this context, significant research has been carried out in the field of electric and hybrid-electric aircraft propulsion. Driven by significant strides made by the automotive industry regarding electric battery technology, the aspirational goal of useful electric flight is now within reach. Significant challenges nonetheless remain regarding the certification of these new vehicles to ensure an equivalent level of safety. Indeed, the behavior of electric powertrains is more complex than that of traditional powertrains and features additional thermal and ageing constraints that need to be contended with. Moreover, the ability of many of these vehicles to fly both on their wing or on their rotors brings another level of sophistication that will increase the workload of flight crews. Combined, these might adversely impact the safety of flight. This research aims to elucidate some of these challenges by providing insights into the behavior and idiosyncracies of new electrified vehicles and by identifying visual cues that should be provided to flight crews to support safe decisionmaking in the cockpit. Besides these visual cues, we explore functionalities that a Trajectory Energy Management system could feature to improve flight safety by providing insights into the management of stored usable energy and by monitoring critical parameters of electrified powertrains. This paper includes two use-cases in which the functionality of the Trajectory Energy Management system is explored for pre-flight planning and in-flight diversion decisionmaking applications

Zero-Emission Regional Aviation in Sweden

Presented at the 33rd ICAS Congress, Sweden (2022).Regional air operations, which can be defined as the transportation of passengers using smaller aircraft over short distances, have been overlooked in recent years by airlines focusing on high volume and profitable routes between large airports. Despite this shift of focus, the airport infrastructure still exists in many smaller communities between which demand for air travel exists. The emergence of new air vehicles designed for shorter routes could stimulate efficient and profitable operations, especially if they leverage currently underutilized and paid-for airports. However, new regional air operations need to be sustainable to be successful in a world striving for a carbon-neutral future, especially since air travel over short distances can be substituted by other means of transportation with a smaller environmental footprint such as cars, trains, or buses. Many different paths are envisioned to reach zero-emission goals. These range from technology advancements to new powertrain configurations, and from new transportation policies to new emission offsetting schemes. It is however not clear how these different paths interact and how solutions could be optimally combined. Analyses are therefore required to estimate future demand for air travel and to assess the feasibility of zero-emission regional aviation with the objective to support decision-making about viable and sustainable paths for new regional air operations. The developed modeling environment is implemented in Sweden and allows for an environmental assessment of various scenarios. Significant untapped demand is uncovered between smaller markets, and given fuel and energy consumption for these operations, it is likely that sustainable advanced regional air mobility will be possible in Sweden provided technology transitions can be made

Trajectory Energy Management Systems for eVTOL Vehicles: Modeling, Simulation and Testing

Presented at AIAA AVIATION Forum 2022The rise of electric aircraft propulsion methods, the increased use of automated and integrated flight control systems, and the envisioned use of personal Vertical Takeoff and Landing (VTOL) vehicles in urban environments lead to novel technical and regulatory challenges for aircraft manufacturers, certification authorities and operators. The combination of electric propulsion, where energy reserves and powertrain performance are highly sensitive to the environment, and VTOL, where the aircraft cannot simply glide to an emergency landing, generates the need for Trajectory Energy Management (TEM). The TEM task involves the manipulation of flight and propulsion controls to achieve a planned flight profile. The TEM system must provide the pilot or automated control system with guidance cues to achieve a planned flight profile, to maintain an energy-optimal trajectory, to avoid deviations from the flight plan causing increases in energy and power consumption, and to mitigate the risk of energy completion. As the pilot must manage both the energy source and flight dynamics energy state, the TEM system must provide sufficient information to the pilot, so that the pilot can perform the mission. This research is intended to define some requirements for energy management such that the pilot can safely accomplish an intended profile and land with enough energy reserves. These requirements must be defined based on prototype algorithm development, simulation results, and flight test data

Modeling and Simulation of Novel Electric/Hybrid Electric Multicopter Architectures for Urban Air Mobility

Presented at AIAA Propulsion and Energy Forum, August 9-11, 2021, VIRTUAL EVENTThis paper introduces a dynamic simulation environment developed for novel multi-copter aircraft architectures. The development is motivated by the need to better understand the safety implications of architectural design choices and to provide a formal reliability assessment framework for new Vertical Take-Off and Landing (VTOL) concepts able to consider various airframe and subsystems dynamic behavior. The concepts of interests are different multi-copters configurations investigated by NASA and featuring either electric, hybrid electric, or turboshaft driven powertrains. The simulation environment is a timemarching dynamic simulator formulated using physics-based subsystem models for the batteries, electric motors, turboshaft engines and electric generators. Identified fault modes are integrated into the subsystem models for subsequent use during reliability assessments. The impacts of subsystem faults are propagated to the vehicle flight dynamic response for analysis of their impact on the ability of the vehicle to sustain safe operations. Detailed features of the electric quadrotor model are provided to illustrate the simulation capabilities. Some faults are inserted on the different aircraft in hover and the subsystems behavior is successfully propagated at the vehicle level

CowN Sustains Nitrogenase Turnover in the Presence of the Inhibitor Carbon Monoxide

Nitrogenase is the only enzyme capable of catalyzing nitrogen fixation, the reduction of dinitrogen gas (N2) to ammonia (NH3). Nitrogenase is tightly inhibited by the environmental gas carbon monoxide (CO). Nitrogen-fixing bacteria rely on the protein CowN to grow in the presence of CO. However, the mechanism by which CowN operates is unknown. Here, we present the biochemical characterization of CowN and examine how CowN protects nitrogenase from CO. We determine that CowN interacts directly with nitrogenase and that CowN protection observes hyperbolic kinetics with respect to CowN concentration. At a CO concentration of 0.001 atm, CowN restores nearly full nitrogenase activity. Our results further indicate that CowN’s protection mechanism involves decreasing the binding affinity of CO to nitrogenase’s active site approximately tenfold without interrupting substrate turnover. Taken together, our work suggests CowN is an important auxiliary protein in nitrogen fixation that engenders CO tolerance to nitrogenase