A machine learning–based high volume sensor classification approach using clustering, statistical analysis, and screening on thermal vacuum test data in a medium-sized satellite

A number of disciplines (mechanics, structures, thermal, and optics) are needed to design and build Space Camera. Separate design models are normally constructed by each discipline CAD/CAE tools. Design and analysis is conducted largely in parallel subject to requirements that have been levied on each discipline, and technical interaction between the different disciplines is limited and infrequent. As a result a unified view of the Space Camera design across discipline boundaries is not directly possible in the approach above, and generating one would require a large manual, and error-prone process. A collaborative environment that is built on abstract model and performance template allows engineering data and CAD/CAE results to be shared across above discipline boundaries within a common interface, so that it can help to attain speedy multivariate design and directly evaluate optical performance under environment loadings. A small interdisciplinary engineering team from Beijing Institute of Space Mechanics and Electricity has recently conducted a Structural/Thermal/Optical (STOP) analysis of a space camera with this collaborative environment. STOP analysis evaluates the changes in image quality that arise from the structural deformations when the thermal environment of the camera changes throughout its orbit. STOP analyses were conducted for four different test conditions applied during final thermal vacuum (TVAC) testing of the payload on the ground. The STOP Simulation Process begins with importing an integrated CAD model of the camera geometry into the collaborative environment, within which 1. Independent thermal and structural meshes are generated. 2. The thermal mesh and relevant engineering data for material properties and thermal boundary conditions are then used to compute temperature distributions at nodal points in both the thermal and structures mesh through Thermal Desktop, a COTS thermal design and analysis code. 3. Thermally induced structural deformations of the camera are then evaluated in Nastran, an industry standard code for structural design and analysis. 4. Thermal and structural results are next imported into SigFit, another COTS tool that computes deformation and best fit rigid body displacements for the optical surfaces. 5. SigFit creates a modified optical prescription that is imported into CODE V for evaluation of optical performance impacts. The integrated STOP analysis was validated using TVAC test data. For the four different TVAC tests, the relative errors between simulation and test data of measuring points temperatures were almost around 5%, while in some test conditions, they were even much lower to 1%. As to image quality MTF, relative error between simulation and test was 8.3% in the worst condition, others were all below 5%. Through the validation, it has been approved that the collaborative design and simulation environment can achieved the integrated STOP analysis of Space Camera efficiently. And further, the collaborative environment allows an interdisciplinary analysis that formerly might take several months to perform to be completed in two or three weeks, which is very adaptive to scheme demonstration of projects in earlier stages.

Environmental testing of spacecraft flight hardware is performed to detect design and workmanship defects and verify mission requirements prior to launch. At the space vehicle level of assembly, the thermal vacuum test simulates an environment particularly well-suited for verifying mission performance requirements. In this paper, the test objectives of the space vehicle thermal vacuum test are reviewed and an assessment is made of the effectiveness and value of the test. Recent thermal vacuum test data is used to determine how the uniqueness of the thermal vacuum test environment achieves test purposes and how the test ensures mission assurance for space vehicles.

The Cross-track Infrared Sounder (CrIS) on board the Suomi National Polar-Orbiting Partnership (S-NPP) Satellite, NOAA-20, and future Joint Polar Satellite System (JPSS) satellites J2 to J4 provide the hyperspectral infrared observations for profiling atmospheric temperature, moisture and greenhouse gases globally. In this study, the J2 CrIS prelaunch spectral calibration parameters including detector focal plane geometry (FOV size and offset angles, referred to as instrument line shape (ILS)) and Neon lamp effective wavelength are derived from the thermal vacuum (TVAC) gas cell test data. These derived parameters are evaluated using the spectral cross-correlation method by comparing with the simulated spectral lines from the line-by-line radiative transfer model (LBLRTM).

The purpose of the Thermal Testing Measurements Report (Scientific Analysis Report) is to document, in one report, the comprehensive set of measurements taken within the Yucca Mountain Project Thermal Testing Program since its inception in 1996. Currently, the testing performed and measurements collected are either scattered in many level 3 and level 4 milestone reports or, in the case of the ongoing Drift Scale Test, mostly documented in eight informal progress reports. Documentation in existing reports is uneven in level of detail and quality. Furthermore, while all the data collected within the Yucca Mountain Site Characterization Project (YMP) Thermal Testing Program have been submitted periodically to the Technical Data Management System (TDMS), the data structure--several incremental submittals, and documentation formats--are such that the data are often not user-friendly except to those who acquired and processed the data. The documentation in this report is intended to make data collected within the YMP Thermal Testing Program readily usable to end users, such as those representing the Performance Assessment Project, Repository Design Project, and Engineered Systems Sub-Project. Since either detailed level 3 and level 4 reports exist or the measurements are straightforward, only brief discussions are provided for each data set. These brief discussions for different data sets are intended to impart a clear sense of applicability of data, so that they will be used properly within the context of measurement uncertainty. This approach also keeps this report to a manageable size, an important consideration because the report encompasses nearly all measurements for three long-term thermal tests. As appropriate, thermal testing data currently residing in the TDMS have been reorganized and reformatted from cumbersome, user-unfriendly Input-Data Tracking Numbers (DTNs) into a new set of Output-DTNs. These Output-DTNs provide a readily usable data structure, including graphical displays and comprehensive spreadsheets. In some cases, there was no need to reformat or restructure Input-DTNs so they remained unchanged. Thermal testing measurement data come from the characterization (pre-heating/baseline and post-cooling) and testing (heating and cooling) phases of the Large Block Test (LBT), the Single Heater Test (SHT), and the Drift Scale Test (DST). Since the LBT and SHT are completed, all phases of those two tests are addressed. DST measurements addressed in this report include preheating and the entire four-year heating phase, which ended January 14, 2002. Discussion of measurements from the ongoing cooling phase will be included in future revision(s) of this report.

The article educes three thermal comfort indexes correspond to three different types of underground space. In addition, it revises and classifies the indexes by thermal comfort test data. At the same time, it takes dissatisfaction rate of questionnaire as the gist of subjective evaluation and thermal comfort index value as the gist of objective evaluation to assess the thermal comfort of underground space. On this basis, take the thermal comfort test data measured in underground malls for example to assess the thermal comfort.

This paper reviews the industry roadmaps on commercial-off-the shelf (COTS) microelectronics packaging technologies covering the current trends toward further reducing size and increasing functionality. Due to the breadth of work being performed in this field, this paper presents only a number of key packaging technologies. The topics for each category were down-selected by reviewing reports of industry roadmaps including the International Technology Roadmap for Semiconductor (ITRS) and by surveying publications of the International Electronics Manufacturing Initiative (iNEMI) and the roadmap of association connecting electronics industry (IPC). The paper also summarizes the findings of numerous articles and websites that allotted to the emerging and trends in microelectronics packaging technologies. A brief discussion was presented on packaging hierarchy from die to package and to system levels. Key elements of reliability for packaging assemblies were presented followed by reliabilty definition from a probablistic failure perspective. An example was present for showing conventional reliability approach using Monte Carlo simulation results for a number of plastic ball grid array (PBGA). The simulation results were compared to experimental thermal cycle test data. Prognostic health monitoring (PHM) methods, a growing field for microelectronics packaging technologies, were briefly discussed. The artificial neural network (ANN), a data-driven PHM, was discussed in details. Finally, it presented inter- and extra-polations using ANN simulation for thermal cycle test data of PBGA and ceramic BGA (CBGA) assemblies.

Thermal vacuum test is an important means of verifying the reliability of spaceborne units in space environments. Usually, the same type of spaceborn units are subjected to thermal vacuum test according to the specified test conditions before integrated into subsystem. This traditional thermal test methods cannot meet the requirements of Nano satellites in terms of timeliness and cost, which feature low cost and short manufacturing cycle. In order to reduce the cost under the premise of ensuring the quality, this paper proposes a overall thermal test method for GNC sub-system of Nano satellites to replace the original individual thermal tests. This paper first demonstrates the effectiveness of the thermal test, and then proposes the criteria for controlling the thermal test conditions of the sub-system based on the existing standard system. A satellite GNC sub-system is taken as an example to introduce its thermal vacuum test scheme. Test result shows that thermal mutual interference of DUTs can be eliminated by multi-zone temperature control and adopting different PID parameters for different kinds of units under test, even if their thermal response characteristics vary, which proves the validity of the test scheme designed.

The thermal deformation of reflecting optical system in the ambient temperature affects the system performance greatly. Based on the results of thermal balance test, the paper has made a full analysis to the deformation of reflecting optical system on the high-low temperature using the finite elemernt method,so as to validate whether the optical system meet the requirement of optical image design and temperature. This method can combine the thermal optical analysis and thermal balance test data effectively ,and therefore the most actual thermal optical anslysis model can be obtained to guide the concept and optimization of reflecting optical system.

Accelerated testing consists of a variety of methods aimed at shortening the life of a product or hastening its performance degradation in a short period of time. The purpose of these tests is to quickly obtain data that, when properly modeled and analyzed, can provide the desired information about a product’s lifetime or performance under normal use. Accelerated life testing will subject a product to conditions that exceed normal service parameters in order to uncover defects and potential failure modes. Since the guidelines for statistical analysis of thermal life test data in accelerated life tests (ANSI/IEEE Std. 101-1987) were enacted, they have been used to analyze the results of many experiments. However, Shim (2004) only used a small amount of data obtained from a limited environment for analysis of ANSI/IEEE Std. 101-1987 results, so simulations were conducted using previous research results to supplement the accuracy of the analysis. In this paper, two different systems or materials generated using the Arrhenius equation are compared in an accelerated life test to estimate the correct lifetime.

The turbine blade tip is considered as one of the most critical areas of gas turbine engines. The tip region often lacks durability and is challenging to cool. To achieve successful blade tip cooling designs, ALSTOM engineers are performing state of the art aero thermal analyses of blade tip cooling configurations. This paper describes the approach used for this analysis and draws conclusion for blade tip cooling optimization. Numerical simulations of flow and heat transfer are presented for a modern industrial gas turbine blade with a film cooled tip. The blade tip metal temperature distribution is analyzed for three different blade tip clearances with a detailed CFD analysis around the blade tip performed. The CFD analysis provides flow streamlines through the blade tip as well as a total blade tip leakage flow. Rough streamlines estimates are then used to define a set of control volumes for which dedicated cooling flow mixing is considered. The total mass flowing through all volumes corresponds to the CFD blade tip leakage. For each control volume corresponds a specific Reynolds number that is used to define a corresponding heat transfer coefficient. The latter is obtained from experimental Nusselt number correlations for the different regions of a blade squealer tip (crown, fillet and cavity). Application of the obtained heat transfer coefficient and mixing temperature boundary conditions on a 3D blade tip finite element model, together with an internal cooling flow network associated to the 3D model allows calculating the blade tip metal temperature. Results for two different tip clearances relative to nominal blade tip gap are presented and discussed. Comparison with experimental data such as thermal paint test and metallurgical data are given, showing good agreement with the blade tip cooling modeling introduced in this paper. Cooling performance of the blade tip is discussed based on the modeling approach proposed in this paper. The latter allows drawing conclusions for blade tip cooling optimization.

ASTRO-H is a next-generation X-ray observatory satellite planned for launch in fiscal 2015. Because ASTRO-H is a large structure and requires precise and accurate pointing, an understanding of on-orbit thermal deformation behavior is particularly important to the success of the ASTRO-H mission. In the conventional technique for predicting thermal deformation, testing is performed in a thermal vacuum chamber so asto simulate the temperature distribution on orbit. However, when using this conventional technique it is difficult to observe the detailed characteristics of the tested structures due to the limits of the applied temperature distribution cases. To overcome this problem, we propose a new evaluation technique for ASTRO-H. In our technique, on-orbit prediction of thermal deformation is performed thorough numerical simulation using a finite element (FE) model. The validation and correlation of the FE model are carried out by comparing results with thermal deformation test data collected in advance. This technique is especially suitable for satellites that are exposed to various thermal conditions on orbit. Using this technique, we confirmed all of the requirements for on-orbit pointing accuracy and precision in ASTRO-H.

Artificial neural network-based temperature prediction of a lunar orbiter in thermal vacuum test: Data-driven reduced-order models

Hot Isostatic Pressing (HIPing) has been used by Rolls-Royce to successfully manufacture nuclear plant components such as valves, piping, and pump casings; the majority of these components being manufactured from stainless steels, typically 316L. There are also considered to be potentially significant benefits to be gained by manufacturing large nuclear plant pressure vessels via the HIP process, such vessels commonly being manufactured from Low Alloy Steel (LAS) materials such as ASME SA-508. The benefits would include cost and lead-time reductions, which are particularly pertinent in relation to the competiveness of the power generation market and future nuclear power plant construction. Such vessels are a major cost and are critical path items of the primary plant. Also, material quality improvements and improved inspectability are possible via the HIP process. Welding vessel sections together using Thick-Section Electron Beam Welding (TSEBW) shows significant promise in reducing welding time and the provision of high quality welds, further reducing vessel cost and lead-time. There is also the potential with the use of TSEBW, to reduce weld inspection requirements with the weld being effectively the same as the parent material, i.e. no weld filler material is used. This paper presents an overview of the pioneering work conducted and planned by Rolls-Royce to develop a method of manufacture to combine HIPing and TSEBW to produce nuclear plant pressure vessels. Staged development is covered, starting with small billet manufacture for the purposes of material testing and examination, followed by vessel demonstrators for the purposes of proving the method of manufacture and to provide justification data, e.g. examination, pressure and thermal cyclic test data. In order to provide a balanced perspective, the paper also identifies the key challenges — risks, and capability development requirements necessary to deliver this method of manufacture.

Gravity Probe B is an orbital test of Einstein’s general theory of relativity using gyroscopes. The precession of the gyroscopes will measure both the geodetic effect (6.6 arc sec/yr) through the curved space-time surrounding the Earth and the motional effect (0.042 arc sec/yr) due to the rotating Earth dragging space-time around with it. To achieve the extraordinary accuracies needed to measure these small precessions, it is necessary to have the gyroscopes operating in the following environments: a vacuum of < 10−10 torr; an acceleration level of < 10−10 g’s; a magnetic field of < 10−7 gauss; and a temperature near 2 K. This paper discusses designs that allow scientific instruments to be installed into a dewar at 4.2 K. Methods for structurally supporting the instruments, transferring heat across joints at low temperature in vacuum and excluding air during the insertion process are discussed. The structural support method is designed for Shuttle launch loads. The separable heat transfer joints are needed for cooling the instruments through the four cool vapor cooled shields and structural support in the dewar. Both structural and thermal resistance test data for the joints are presented. A design of a helium purged air lock is discussed that allows the insertion or removal of the instruments into or out of the dewar. The design permits multiple insertions and removals without refurbishment.

Published work on MIC mixers has dealt with downconverter applications [1-3]. This paper describes a low conversion loss upconverter which has been designed to operate over a wide bandwidth with a high level of intermodulation suppression in a space environment. The design and measured performance of an E-plane upconverter for frequency conversion from 4 to 20 GHz is described. The mixer uses beam-lead diodes and is realized in a single-balanced configuration on a soft substrate. The circuit is clamped in the E-plane of a waveguide housing. The conversion loss of the mixer is 6.5 ± 1.1 dB over a 700 MHz RF bandwidth for LO power levels of +11 dBm to +15 dBm, and more than 40 dB suppression of 3rd order intermodulation products is achieved. Thermal and vibration test data show that this configuration is rugged and thus has potential for application in space and other hostile environments.