Developing optical devices and projects for teaching engineering

In this study, an adaptive dynamic programming (ADP) control strategy based on the strain measurement of a fiber Bragg grating (FGB) sensor array is proposed for the vibration suppression of a complicated flexible-sloshing coupled system, which usually exists in aerospace engineering, such as launch vehicles with a large amount of liquid propellant as well as a flexible beam structure. To simplify the flexible-sloshing coupled dynamics model, the equivalent spring-mass-damper (SMD) model of liquid sloshing is employed, and a finite-element method (FEM) dynamic model for the beam structure coupled with the liquid sloshing is mathematically established. Then, a strain-based vibration dynamic model is derived by employing a transformation matrix based on the relationship between displacement and strain of the beam structure. To facilitate the design of a strain-based control, a tracking differentiator is designed to provide the strains’ derivative signals as partial states’ estimations. Feeding the system with the strain measurements and their derivatives’ estimations, an ADP controller with an action-dependent heuristic dynamic programming structure is proposed to suppress the vibration of the flexible-sloshing coupled system, and the corresponding Lyapunov stability of the closed-loop system is theoretically guaranteed. Numerical results show the proposed method can effectively suppress coupled vibration depending on limited strain measurements irrespective of external disturbances.

Collision Probability with Gaussian Mixture Orbit Uncertainty

\nMorphing aircraft has been the research hot topics of new concept aircrafts in aerospace engineering. Telescopic wing is an important morphing technology for morphing aircraft. This paper describes the dynamic equations and kinematic equations based on theorem of momentum and theorem of moment of momentum, which are available for all morphing aircrafts. Meanwhile,as simplified , dynamic equations for rectangular telescopic wing are presented. In order to avoid the complexity using aileron to generate rolling moment , an new idea that asymmetry of wings can generate roll moment is introduced. Finally, roll performance comparison of asymmetric wing and aileron deflection shows that asymmetric telescopic wing can provide the required roll control moment as aileron, and in some cases, telescopic wing has the superior roll performance.\n

In the last decade, Study on the use of natural fibers as synthetic substitute materials or green polymer composites is growing. The growth of green polymer composites has had a significant impact on polymer composite research and innovation. This rapid growth provides advantages over low-cost synthetic fiber composites and reduces adverse impacts on the environment. Because of its potential, this material is applied in various engineering fields, including in the aerospace engineering.
 In recent years, various improvements have been made to natural fiber composite materials to improve physical, mechanical and chemical properties. The aim of this review is to highlight trends in the use of natural fiber polymer composites applied to the aerospace engineering. This review article explains the latest research activities regarding green polymer composite fabrication, advantages of green polymer composites, and applications in the aerospace engineering

This paper introduces the three-axis attitude control of the ESAT platform. ESAT is a modular nanosatellite that implements the popular 10x10x10 cm CubeSat standard, designed for hands-on learning at different educational levels as well as professional training. ESAT features the full set of characteristic spacecraft subsystems (power, on-board data handling, attitude control, communications, and payload). The satellite can be disassembled to focus on each subsystem, one at a time, or used all together, and features a flexible ground segment. Courses using the ESAT platform are imparted in our university, as part of the last year of the master’s degree in Aerospace engineering, and in other institutions like the ESA Academy. They cover aspects ranging from subsystems design to testing and spacecraft operations. In addition, the platform is used in master’s thesis and research activities. Although the version that is currently being used in the courses allows only one-axis attitude control, the ESAT is in continuous development and two prototypes of the satellite have already been developed that allow three-axis control based on reaction wheels and/or magnetorquers, which is essential for the testing and verification of attitude determination and control algorithms. For this purpose, the ground support equipment has also been updated to be able to carry out the turns in three axes, with the development of new testbeds and a complete magnetic field simulator. The present work aims to show the new three-axis platform designs and its main functionalities

This study explores the Fused Deposition Modeling (FDM) additive manufacturing method as a practical alternative for flow characterization applications critical in aerospace technology. While there are significant studies in the literature on high-budget FDM devices for manufacturing high-dimensional consistency parts, research focusing on sub-millimeter riblet geometries using more accessible, practical, and flexible open-source devices remains limited. In this study, a printer that can be mechanically and programmatically modified was used to create parallel riblet patterns resembling wing structures on plates. Microscopic examinations and measurements were conducted on these riblets to address encountered issues. Observations revealed that hardware elements such as nozzle-table distance and nozzle circularity are crucial for homogeneous material extrusion. Additionally, it was observed that software-defined parameters like line width and flow rate significantly affect riblet dimensions. Particularly in experiments involving calibration of these parameters in open-source concept devices, riblet width, inter-riblet spacing, and riblet height were achieved with a high accuracy error rate of up to 1.83%, 1.33%, and 0.19%, respectively. Consequently, this study demonstrated the feasibility of producing riblets in this size and precision using widely available, cost-effective, and customizable FDM devices. Considering the significance of riblet structures in aerospace industries for flow control and surface modifications, this research aims to provide critical insights for the practical and effective production of more complex surface profiles in research and development activities.

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Aeroelastic stability analysis of a pyrotechnic separation plate in subsonic airflow

When dangerous chemical or biological releases occur in the atmosphere, emergency responders and decision makers must assess exposure rates to the affected population, establish evacuation routes, and allocate medical resources We have been working to improve the scientific basis for making such decisions. We believe that future rapid response teams, from LLNI, and other centers of expertise, will use a variety of atmospheric sensors and atmospheric computer models to predict and characterize the movement of chemical or biological releases in urban environments, and that LLNL is likely to contribute expertise in this area. A key advance will be to merge the information and capabilities of computer models with real-time atmospheric data from sensors. The resulting product will dynamically interpolate and extrapolate the raw sensor data into a coordinated ''picture'' or interpretation of the developing flow scenario. The scientific focus of the project was the exploration and development of algorithms to fuse lidar data (which measure wind speed much as a police radar measures vehicle speed) and a dispersion model into a single system. Our goal was to provide the scientific foundation for a combined lidar/model approach capable of accurately tracking the evolution of atmospheric releases on distance scales of about 20 km. The fundamental idea is to create feedbacks, so that lidar data can be used for wind field inputs into a dispersion model, which would, in turn, guide lidar data acquisition by directing more intensive scanning to regions where more data are key to improving the modeling. We created a database of synthetic lidar data that can be used to test algorithms relating to a combined lidar/dispersion model. We obtained the data, which represent nocturnal atmospheric drainage flows in the Salt Lake City Basin, from calculations on the LLNL ASCI White supercomputer with a computational fluid dynamics model running in large-eddy simulation mode. A simple modification of the resulting air-flow data produced radial velocity wind field data, which may be directly compared with real lidar data and substituted for them. We have produced a short animation (which can be viewed in the CD-ROM version of this article) representing drainage flow from the mountains. The assumed position of the lidar was that of an actual lidar that took data in the Urban Dispersion Project, funded by DOE, in the fall of 2000. We studied the ''Terminal Winds'' project at the Lincoln Laboratory of the Massachusetts Institute of Technology. We analyzed algorithms and approaches used by other scientists on related or relevant projects. We evaluated the Gauss-Markov theorem approach and concluded that it will be useful in designing an advanced sensor integration system for incorporating lidar into numerical models, and, in particular, to build a single interpretation of a flow field based on potentially conflicting sensor data We began development of a script-based ''test'' laboratory, which samples the database and provides input to a dispersion model, which was ported and tested on the Frost computer system at LLNL. Our results demonstrate that specially sampled data from numerical models can indeed be a useful surrogate for actual lidar data which can only be gathered currently at great expense. The further development of the algorithms and ideas relating to this project continue at Arizona State University (ASU) where the PI is now an Assistant Professor of Mechanical and Aerospace Engineering. LLNL and ASU have recently established a collaboration entitled ''Advanced Sensor Integration into NARAC's Atmospheric Data Assimilation Program'' which we believe will benefit from the groundwork provided by this LDRD.

Although the dynamic response of orthotropic materials under uniaxial impact loading has been extensively studied, their behavior under multiaxial stress states, which more accurately represent real-world blast and impact scenarios, has received limited attention. To address this gap, this study employed a self-developed biaxial impact testing apparatus to systematically investigate the dynamic mechanical behavior of beech wood, a typical orthotropic material, under three biaxial loading configurations: radial-tangential, radial-longitudinal, and tangential-longitudinal. By combining theoretical derivation with experimental data, it systematically examines stress wave propagation characteristics, strain rate effects, and anisotropy evolution under different loading paths. The results reveal that beech wood exhibits significantly distinct dynamic responses along different material orientations, with a consistent strength hierarchy: longitudinal > radial > tangential. Biaxial loading notably enhances the equivalent stress–strain response and alters the deformation mechanisms and energy absorption behavior. Furthermore, lateral confinement and multiaxial stress coupling are identified as critical factors influencing the dynamic performance. This study provides the first systematic revelation of the strain rate strengthening mechanisms and wave propagation characteristics of orthotropic materials from the perspective of multiaxial dynamic loading, thereby offering theoretical and experimental foundations for developing advanced dynamic constitutive models suitable for complex impact conditions. These findings provide important guidance for the design and evaluation of lightweight impact-resistant structures in fields such as aerospace and protective engineering.

Photostructurable glass-ceramic materials have received significant attention due to their utility in aerospace engineering and micro technology. For example, the ability to fabricate structures in glass is important in the design and integration of micro scale electronic, optical and fluidic devices. Direct-write pulsed UV laser processing techniques have been utilized recently to create patterned 3D microstructures in a lithium-aluminosilicate glass. The direct-write microfabrication process involves the formation of an initial latent image in the glass via UV laser radiation. Thermal-induced ceramization is utilized to develop the latent image into a permanent image. Material removal and microstructure fabrication are then accomplished by preferential isotropic etching of the developed regions.

A number of special issues and sections are on the horizon for the Journal of Aerospace Engineering. We are pleased to announce that we have invited a number of respected researchers to contribute papers for inclusion in upcoming issues and sections. “In Situ Resource Utilization” (ISRU) will feature papers that provide overviews of ISRU and papers in the following areas: beneficiation; drilling, excavation, and mining; structures, site preparation, and construction; and analogues and stimulants for extraplanetary soils. This special issue is being edited by Haym Benaroya of Rutgers University and Philip Metzger and Tony Muscatello, both from the National Aeronautics and Space Administration (NASA) Kennedy Space Center. “Intelligent Unmanned Systems”will be dedicated to research in the design, development, testing, and operation of unmanned aerial vehicles, with a focus on the following areas: actuators/smart sensors and their applications, including smart microelectromechanical systems (MEMS)/nanoelectromechanical systems (NEMS) sensors and vision sensors; and control theories and their applications, including various control theories, distributed or decentralized control methods, distributed and embedded systems, precision motion control, and swarm operation. The guest editors for this special section are Agus Budiyono of Konkuk University, Korea; Bambang Riyanto of Institut Teknologi Bandung, Indonesia; and Hoon Cheol Park of Konkuk University. “Hydraulic and Earth Structures” will focus on issues facing engineers involved in construction and operations in challenging environments as they seek to achieve sustainable development on earth, in space, and on other planetary bodies. In particular, the topics associated with hydraulic structures and materials will be the focus, and they include water flow and sediment transport, GIS for potential disaster detection, seismic capacity of high arch dam, and soilbags for slope treatment. This special section is edited by Pizhong Qiao of Washington State University and Zhongru Wu of Hohai University, China. “Seventy Years of Aerospace Research and Technology Excellence at NASA Glenn Research Center” will celebrate the anniversary of this historic NASA facility located in Cleveland, Ohio. The issue will focus on the research activities over the last seven decades in the following areas: aeropropulsion; power and in-space propulsion; communication, instrumentation, and controls; materials and structures; and microgravity and space environments. The special issue is being edited by Robert Goldberg of NASA Glenn Research Center. We look forward to bringing you these exciting issues in the months to come.

Corrigendum to “Enhanced High-Fidelity and Dynamic Modeling for Power Conditioning Units Synchronized with On-Orbit Satellites” [Aerospace Science and Technology, volume 162 (2025) 110213

Different types of advanced optical fibre sensor systems using similar spectral interrogation principles and potential low-cost polychromator optoelectronic signal processing instrumentation will be presented, and examples of their industrial application are demonstrated. These are such sensors as multimode fibre based humidity, temperature, and pressure sensors with extrinsic microoptical Fabry-Perot transducers for process control in gas industry, UV absorption evanescent field sensors for organic pollution monitoring in groundwater, and single mode fibre Bragg grating (FBG) multiplexed strain & vibration and temperature sensor networks for structural health monitoring applications in electric power facilities, aerospace, railways, geotechnical and civil engineering. Recent results of current investigations applying FBGs and microstructured fibres for chemical sensing will be discussed.

The combination of fibre optics with micro- and nano-structure technologies offers great potential for the realisation of novel sensor concepts. Selected examples of advanced optical fibre sensor systems based on sub-wavelength structured components will be presented. Such examples are highly sensitive extrinsic fibre-optic humidity and hydrocarbon sensors for application in gas industry and in environmental monitoring using nano-porous thin-film Fabry-Perot transducer elements, or intrinsic fibre Bragg grating sensor networks for structural health monitoring (i.e., monitoring mechanical strain and deformation, vibration, temperature) in electric power facilities, aerospace, railways and geotechnical engineering as well as for chemical detection (e.g., hydrogen). Additionally, new concepts for chemical and biochemical sensing applying plasmonic metal nano-particles, photonic crystal fibres, and optical nano-wires will be discussed.