Wildland fire simulation is a useful tool for studying wildland fires and for developing new technologies to help wildland fire management. This paper presents an effort of developing wildland fire simulation as a ser...
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ISBN:
(纸本)9798331539580
Wildland fire simulation is a useful tool for studying wildland fires and for developing new technologies to help wildland fire management. This paper presents an effort of developing wildland fire simulation as a service that is accessible to broader users. The developed simulation service supports fire spread simulation, fire suppression simulation, and prescribed fire simulation with dynamic ignitions, and is accessible through a graphic user interface and an application programming interface (API). We present the underlying DEVS-FIRE simulation model, the design of the cloud-based wildland fire simulation service, and some preliminary results.
The order of execution of computational kernels for Single-Program, Multiple-Data (SPMD) programs is usually determined at compile time. These static predetermined schedules can lead to performance issues at runtime, ...
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ISBN:
(数字)9781624107047
ISBN:
(纸本)9781624107047
The order of execution of computational kernels for Single-Program, Multiple-Data (SPMD) programs is usually determined at compile time. These static predetermined schedules can lead to performance issues at runtime, and are difficult to implement for inhomogeneous situations, such as variable-order or multi-physics applications. It is especially challenging to generate performant schedules when it is unknown whether specific kernels require execution, as a function of user inputs, or the kernel execution time changes dependent on the hardware. This paper presents a solution to this problem by dynamically scheduling computational kernels at runtime using directed acyclic graphs to track the data dependencies between kernels. This system is specifically designed to leverage existing computational infrastructure as much as possible, facilitating the extension to legacy applications. This scheduling system is demonstrated using the eddy high-order multi-physics solver developed at NASA. The details regarding the implementation, our experiences using this system, and performance are discussed.
When a new requirement emerges for an existing application programming interface (API) there are several decisions to make. Most of these decisions are difficult to change later when many stakeholders are involved. Th...
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ISBN:
(纸本)9798400716836
When a new requirement emerges for an existing application programming interface (API) there are several decisions to make. Most of these decisions are difficult to change later when many stakeholders are involved. This means that bad decisions can create a lot of complications and thus effort. First it needs to be decided whether to modify an existing operation, e.g. an API endpoint, grow it or rather create a new operation from scratch. When designing a FRESH OPERATION there are many possibilities and decisions to make. This offers a variety of pitfalls. One option to avoid them is to create a CLOSE RELATIVE. This means that rather than incorporating as many innovations as possible the existing API landscape is carefully examined for aspects and decisions that are worth to be reused. These are then incorporated into the new operation. This paper presents the two patterns FRESH OPERATION and CLOSE RELATIVE and shows their relation to neighboring patterns.
Two fully automated Python- and MATLAB-HFSS interfaces without VBA scripts are presented. They are automated since to run they require only the HFSS file describing the model and either the Python or MATLAB scripts of...
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ISBN:
(数字)9782874870774
ISBN:
(纸本)9798350385892;9782874870774
Two fully automated Python- and MATLAB-HFSS interfaces without VBA scripts are presented. They are automated since to run they require only the HFSS file describing the model and either the Python or MATLAB scripts of the APIs. All the auxiliary files are generated directly by the APIs. As an example, the findings are applied to the design of the external quality factor in microwave cavity filters.
Digital TV (DTV) receivers are flexible products that may be enhanced with features that exploit their basic resources: Audio, video, and general media decoding, manipulation, and presentation. However, a new communic...
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Numerical solutions of flatness-based reformulation of optimal control problems lead to an optimization problem with fewer variables and constraints. However, the expressions for the states and controls in terms of th...
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Numerical solutions of flatness-based reformulation of optimal control problems lead to an optimization problem with fewer variables and constraints. However, the expressions for the states and controls in terms of the flat output variables can be highly nonlinear and complicated. Hence, this may lead to expensive function evaluations within the optimization problem, degradation of convexity, and issues with convergence. Thus, a flatness-based reformulation of the optimal control problems may not be a viable alternative for computational guidance and control. Alternatively, a novel flatness-based reduced Hessian sequential quadratic programming algorithm is developed in this paper to solve optimization problems for a six-degree-of-freedom aircraft. An analytical null space basis is derived from the linearized differential constraints, which leads to a reduced-dimensional quadratic program with the discretized flat outputs as decision variables. Unlike flatness-based reformulation of the optimal control problem, the null space/reduced Hessian method does not introduce additional nonlinearity and preserves the convexity of the optimization problem. A nonlinear model predictive control problem is solved to demonstrate the reduced Hessian algorithm. The algorithm is validated and Monte Carlo trials are performed to assess the effectiveness of the approach. Computational studies show that the current approach is faster than methods that directly exploit sparsity up to a factor of five.
The increasing prominence of Unmanned Aerial Vehicles (UAVs) in research has resulted in a heightened focus on their applications in both civilian and military sectors. As UAVs persist in playing an essential role in ...
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ISBN:
(数字)9781624107047
ISBN:
(纸本)9781624107047
The increasing prominence of Unmanned Aerial Vehicles (UAVs) in research has resulted in a heightened focus on their applications in both civilian and military sectors. As UAVs persist in playing an essential role in the future, understanding the minimum safety distances required for swarms during transportation between locations becomes crucial. Maintaining optimal safety distances is vital for preventing collisions and maximizing the efficient use of airspace. This paper investigates a Machine Learning (ML) approach to address this concern for fleets comprising ten or more swarm vehicles, employing a PX4/ROS/Gazebo-based digital simulation system framework to determine the minimum safety distance in various UAV transportation settings.
Structural layout and weight estimation are critical elements of aircraft conceptual design. Historically, designers have often relied on empirical equations to estimate the structural weight during early stages of a ...
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ISBN:
(数字)9781624107047
ISBN:
(纸本)9781624107047
Structural layout and weight estimation are critical elements of aircraft conceptual design. Historically, designers have often relied on empirical equations to estimate the structural weight during early stages of a design due to the lack of robust and fast structural layout tools. This reliance on estimating equations is obviously problematic for atypical or novel designs that do not align themselves well with historical data. Conversely, the M4 Structures Studio (M4SS) software package is a physics-based structural modeling tool capable of rapidly defining aircraft structural layouts with a parametric relationship to a geometry model. The following effort outlined in this paper demonstrates the ability for M4SS to interface with geometric models developed within the Engineering Sketch Pad (ESP) framework. The interface relies on geometric attribution to drive semi-automation of the structural layup, all while preserving parametric connectivity between the structural and geometric models. This parametric connectivity allows a designer to morph the structural model by simply making changes to the parameters defining the vehicles outer model line. This interface and integration is demonstrated on both generic transport and fighter models.
Safety Assessment is paramount in aircraft design, and increasing aircraft complexity has led to the need for aircraft safety assessments in the early design stages. For unconventional aircraft or aircraft with novel ...
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ISBN:
(数字)9781624107047
ISBN:
(纸本)9781624107047
Safety Assessment is paramount in aircraft design, and increasing aircraft complexity has led to the need for aircraft safety assessments in the early design stages. For unconventional aircraft or aircraft with novel propulsion or system technologies, it becomes even more critical to investigate safety as early as possible in the design process to avoid unfeasible aircraft configurations and system architectures. In this context, the Particular Risk Analysis (PRA) and the Zonal Safety Analysis (ZSA) are essential to assess early. Both of them require a threedimensional (3D) model of the aircraft and systems. To analyze many aircraft configurations and system architectures, the 3D parametric model and the PRA and ZSA require automation. This paper reviews methodologies for performing the ZSA and PRA from a systems point-of-view and proposes parametric zone definition, identification of risk zones, and a conceptual level analysis of the component placement strategy. The effectiveness of the proposed approach is demonstrated with a main landing gear ZSA and a tire burst PRA case study for a conventional aircraft. The presented work is a step towards integrating system safety analysis into multidisciplinary analysis and optimization environments, thus increasing conceptual design maturity and reducing development time.
Healthcare-related research studies often deploy ecological momentary assessment techniques to sample information from participants in their natural environment. This paper presents an online system to support remote ...
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ISBN:
(纸本)9798350341034
Healthcare-related research studies often deploy ecological momentary assessment techniques to sample information from participants in their natural environment. This paper presents an online system to support remote access of ecological self-report and actigraphy-based measurements for individuals with Amyotrophic Lateral Sclerosis (ALS) and their caregivers. The presented framework includes a custom mobile app and makes use of a web-based application programming interface for data collection with wrist-worn actigraphy devices. The system was evaluated with a research protocol to measure sleep, fatigue, and pain for individuals with ALS and their caregivers (N=8) over a consecutive seven-day period. Though daily self-report response rates were widespread (0%-100%) and the remote actigraphy collection varied in reliability, novel relationships between individuals with ALS and their caregivers were identified from the collected data. Online, ecological systems can support real-time remote monitoring and/or interventions to help understand diseases like ALS and advance healthcare research.
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