SiC JFET/P-MOSFET cascode for SSCB and inrush current limiter in 300V DC power systems

This work presents a solid-state distribution and protection switch based on the SiC JFET/P-MOSFET cascode structure. The concept is aimed for 300V applications, but it can be adapted easily to other voltages. Detailed circuit design and simulation is discussed, as well as the potential application in 300V bus voltage satellite

Methodology of experimental determination of the spherical harmonics of the magnetic field of technical objects .

Проведен сравнительный анализ основополагающих принципов, лежащих в основе методов экспериментального определения сферических гармоник магнитного поля технических объектов. Предложена классификация методов выделения вкладов и определения величин коэффициентов сферических гармоник магнитного поля. Установлены взаимосвязи между рассмотренными методами и принципами, положенными в основу функционирования соответствующих измерительных систем для практического сферического гармонического анализа магнитного поля.A comparative analysis of methods for the experimental determination of the spherical harmonics of the magnetic field of technical objects has been carried out. The fundamental principles for creation of spherical harmonics of the magnetic field have been represented. The interrelation of the established principles with metrological means of measuring of spherical harmonics of the magnetic fields is shown. A classification of the methods for separating of contributions and determining the magnitudes of the coefficients of the spherical harmonics of the magnetic field is proposed. It is proposed to use the classification as a theoretical basis for creating new methods and means for conducting a practical spherical harmonic analysis of the magnetic field of technical objects

Haynes 242 alloy for LARES 2 satellite

none6noThe satellite LARES 2 is designed to test dragging of inertial frames, or frame-dragging, predicted by Einstein’s theory of General Relativity, with accuracy of a few parts in a thousand. For this purpose, besides the typical requirements for a space construction, a high density alloy must be used. In this paper are reported the studies performed on a nickel alloy, the Haynes 242, that is considered a possible candidate for manufacturing all the metallic parts of LARES 2 and other passive geodetic satellites. Haynes 242 density and mechanical properties are compliant with the requirements of the mission. Three different casting with the nominal composition of the alloy have been prepared and tested along with a commercial bar of Haynes 242. The results of tensile and hardness tests on several specimens with different aging time are reported, along with the relevant metallographic analysis. Furthermore, a test on the machinability, performed on a screw, which is the most demanding item from the manufacturing point of view, is reported.openD. Pilone, A. Brotzu, F. Felli, I. Ciufolini, B. Negri, C. ParisPilone, D.; Brotzu, A.; Felli, F.; Ciufolini, I.; Negri, B.; Paris, C

Haynes 242 Alloy for Lares 2 Satellite

The satellite LARES 2 is designed to test dragging of inertial frames, or frame-dragging, predicted by Einstein’s theory of General Relativity, with accuracy of a few parts in a thousand. For this purpose, besides the typical requirements for a space construction, a high density alloy must be used. In this paper are reported the studies performed on a nickel alloy, the Haynes 242, that is considered a possible candidate for manufacturing all the metallic parts of LARES 2 and other passive geodetic satellites. Haynes 242 density and mechanical properties are compliant with the requirements of the mission. Three different casting with the nominal composition of the alloy have been prepared and tested along with a commercial bar of Haynes 242. The results of tensile and hardness tests on several specimens with different aging time are reported, along with the relevant metallographic analysis. Furthermore, a test on the machinability, performed on a screw, which is the most demanding item from the manufacturing point of view, is reported

Quantum-limited measurements of optical signals from a geostationary satellite

The measurement of quantum signals that traveled through long distances is of fundamental and technological interest. We present quantum-limited coherent measurements of optical signals, sent from a satellite in geostationary Earth orbit to an optical ground station. We bound the excess noise that the quantum states could have acquired after having propagated 38600 km through Earth's gravitational potential as well as its turbulent atmosphere. Our results indicate that quantum communication is feasible in principle in such a scenario, highlighting the possibility of a global quantum key distribution network for secure communication.Comment: 8 pages (4 pages main article, 4 pages supplementary material), 9 figures (4 figures main article, 5 figures supplementary material), Kevin G\"unthner and Imran Khan contributed equally to this wor

Advanced Space Flight Mechanical Qualification Test of a 3D- Printed Satellite Structure Produced in Polyetherimide ULTEMTM

The aim of this work is to demonstrate the use of additive manufacturing with thermoplastic material in the whole functional structure of spacecraft and to mechanically qualify it for space flight. For such purpose, an 8 U CubeSat structure was manufactured in polyetherimide (PEI) ULTEM™ through 3D printing and passed several vibration tests. The results are compared with those obtained in the qualification of the same structure manufactured in aluminum alloy AA-6082 T651 through a conventional CNC method. The qualification consisted of passing the vibration requirements in quasi-static, sine, and random tests to fly in PSLV launcher. Finally, a robustness test for the 3D-printed structure is included, and all the results are analyzed. This study is being part of the H2020 European Project ReDSHIFT (Project ID 687500)

Оценка опасных состояний и рисков мехатронных систем техники для экстремальных условий эксплуатации

Basinyuk V. L. Assessment of dangerous conditions and risks of mechatronic systems of equipment for extreme operating condition

Method for control by orbital spacecraft magnetic cleanliness based on multiple magnetic dipole models with consideration of their uncertainty

Aim. Development of method for control by orbital spacecraft magnetic cleanliness based on multiple magnetic dipole models using compensation of the initial magnetic field with consideration of magnetic characteristics uncertainty. Methodology. Orbital spacecraft multiple magnetic dipole models calculated as solution of nonlinear minimax optimization problem based on near field measurements for prediction orbital spacecraft far magnetic field magnitude. Nonlinear objective function calculated as the weighted sum of squared residuals between the measured and predicted magnetic field. Weight matrix calculated as inverse covariance matrix of random errors vector. Values of magnetic moments and coordinates of placement of compensating magnetic dipoles for compensation of the orbital spacecraft initial magnetic field also calculated as solution of nonlinear minimax optimization problem. Both solutions of this nonlinear minimax optimization problems calculated based on particle swarm nonlinear optimization algorithms. Results. Results of prediction spacecraft far magnetic field magnitude based on orbital spacecraft multiple magnetic dipole models using near field measurements and compensation of the initial magnetic field with consideration of orbital spacecraft magnetic characteristics uncertainty for ensuring the orbital spacecraft magnetic cleanliness. Originality. The method for control by orbital spacecraft magnetic cleanliness based on multiple magnetic dipole models using compensation of the initial magnetic field with consideration of magnetic characteristics uncertainty is developed. Practical value. An important practical problem of ensuring orbital spacecraft magnetic cleanliness based on orbital spacecraft multiple magnetic dipole models using near field measurements and compensation of the initial magnetic field with consideration of orbital spacecraft magnetic characteristics uncertainty solved.Мета. Розробка методу управління магнітною чистотою орбітального космічного апарату на основі багатодипольної моделі магнітного поля з використанням компенсації вихідного магнітного поля та з урахуванням невизначеності магнітних характеристик. Методологія. Багатодипольна модель магнітного поля орбітального космічного апарату розрахована як рішення задачі нелінійної мінімаксної оптимізації на основі вимірювань ближнього магнітного поля для прогнозування величини дальнього магнітного поля. Нелінійна цільова функція обчислена у вигляді зваженої суми квадратів залишків між виміряним і прогнозованим магнітним полем. Вагова матриця розрахована у вигляді оберненої коваріаційної матриці вектора випадкових помилок. Значення магнітних моментів і координати розміщення компенсуючих магнітних диполів для компенсації початкового магнітного поля орбітального космічного апарату також розраховані як рішення нелінійної задачі мінімаксної оптимізації. Рішення обох задач нелінійної мінімаксної оптимізації розраховані на основі алгоритмів нелінійної оптимізації роєм частинок. Результати. Результати прогнозування величини дальнього магнітного поля орбітального космічного апарату на основі багатодипольної моделі магнітного диполя з використанням вимірювань ближнього поля та компенсації вихідного магнітного поля з урахуванням невизначеності магнітних характеристик для забезпечення магнітної чистоти орбітального космічного апарату. Оригінальність. Розроблено метод управління магнітною чистотою орбітального космічного апарату на основі багатодипольної моделі магнітного поля з використанням компенсації вихідного магнітного поля та з урахуванням невизначеності магнітних характеристик. Практична цінність. Вирішено важливу практичну задачу забезпечення магнітної чистоти орбітального космічного апарату на основі багатодипольної моделі магнітного диполя з використанням вимірювань ближнього поля та компенсації вихідного магнітного поля з урахуванням невизначеності магнітних характеристик орбітального космічного апарату

On the Development of Shell Buckling Knockdown Factors for Stiffened Metallic Launch Vehicle Cylinders

From the 1920s to the early 1970s, many shell buckling experiments were conducted in an effort to understand the complex buckling behavior exhibited by thin-walled cylindrical shells, to provide data to correlate with new shell stability theories, and provide design guidelines. Typically, the experiments yielded buckling loads that were substantially lower than the corresponding analytical predictions, which were based on simplified linear bifurcation analyses of geometrically perfect shells with nominal dimensions and idealized boundary conditions. The seminal works by von Krmn and Tsien, by Donnell and Wan, and by Koiter identified small deviations from the idealized geometry of a shell, known as initial geometric imperfections, as a primary source of the discrepancy between corresponding analytical predictions and experimental results. However, the computational tools and capabilities at that time could not perform the nonlinear analyses needed to assess the effects of these imperfections on the buckling behavior of thin-walled shells. Thus, buckling design allowables were determined by establishing lower bounds to test data. Specifically, empirical design factors, that have become known as knockdown factors, were determined and were to be used in conjunction with linear bifurcation analyses for simply supported shells; that is, these empirical factors were used to "knock down" the value of the unconservative simplified analytical prediction. This approach to shell buckling design has proved satisfactory for most design purposes and remains prominent in industry practice, as evidenced by the extensive use of the NASA space vehicle design criteria and recommendations. Unfortunately, the current design guidelines have not been updated since they were first published in the late 1960s and may not be able to take full advantage of modern materials, precision manufacturing processes, and new structural concepts