Coarse-to-Fine Image Matching-Based Footprint Camera Calibration of the GF-7 Satellite

The GF-7 satellite is China’s first high-resolution stereo mapping satellite that reaches sub-meter resolution, equipped with new-type payloads, such as an area array footprint camera that can achieve synchronization acquisition of laser spots. When the satellite is in space, the variation of camera parameters may occur due to launch vibration and environmental changes, and on-orbit geometric calibration thereby must be made. Coupled with the data from the GF-7 satellite, this paper constructs a geometric imaging model of the area array footprint camera based on the two-dimensional direction angle, and proposes a coarse-to-fine “LPM-SIFT + Phase correlation” matching strategy for the automatic extraction of calibration control points. The single-image calibration experiment shows that the on-orbit geometric calibration model of the footprint camera constructed in this paper is correct and effective. The matching method proposed is used to register the footprint images with the DOM (Digital Orthophoto Map) reference data to obtain dense control points. Compared with the calibration result using a small number of manually collected control points, the root mean square error (RMSE) of the residual of the control points is improved from half a pixel to 1/3, and the RMSE of the same orbit checkpoints in the image space is improved from 1 pixel to 0.7. It can be concluded that using the coarse-to-fine image matching method proposed in this paper to extract control points can significantly improve the on-orbit calibration accuracy of the footprint camera on the GF-7 satellite.

Studi Implementasi " Smart Grid Solar PV System" Di Gedung G Universitas Muhammadiyah Jember

Pemanfaatan energi listrik di Gedung G Universitas Muhammadiyah Jember bersumber dari PLN sebesar 6,6 KVA. Energi listrik yang digunakan untuk mencukupi kebutuhan energi listrik 3 lantai. Penggunaan energi listrik di Gedung G juga memanfaatkan energi tambahan. Teknologi yang digunakan Smart Grid Solar PV System yang bekerja secara hybrid dengan jaringan PLN untuk memenuhi beban. Analisis data dalam studi ini menggunakan metode pengumpulan data berupa daya pada panel surya menggunakan aplikasi perangkat lunak IMEON Manager dengan waktu pengambilan selama 4 minggu dengan waktu 7 jam per hari dengan rentang waktu 10 menit. Estimasi total kebutuhan energi harian Gedung G Universitas Jember sebesar 1980 kWh/hari untuk mengantisipasi penambahan beban maka energi dicadangkan sebesar 30% dari total energi yang dicadangkan sebesar 594,0 Wh/hari. Sehingga daya yang dibangkitkan dengan area array 678,8 m2 dan 14 jumlah panel surya sebesar 3640 Wp.

Fatigue Life of Sn3.0Ag0.5Cu Solder Alloy Under Combined Cyclic Shear and Constant Tensile/Compressive Loads

Solder joints in electronic assemblies experience damage due to cyclic thermomechanical loading that eventually leads to fatigue fracture and electrical failure. While solder joints in smaller, die-sized area-array packages largely experience shear fatigue due to thermal expansion mismatch between the component and the substrate, larger area-array packages experience a combination of cyclic shear and axial tensile/compressive loads due to flexure of the substrate. Additionally, on larger processor packages, the attachment of heatsinks further exacerbates the imposed axial loads, as does package warpage. With the increase in size of packages due to 2.5D heterogeneous integration, the above additional axial loads can be significant. Thus, there exists a critical need to understand the impact on fatigue life of solder joints with superposed compressive/tensile loads on the cyclic shear loads. In this paper, we describe a carefully constructed multi-axial microprecision mechanical tester as well as fatigue test results on Sn3.0Ag0.5Cu (SAC305) solder joints subjected to controlled cyclic shear and constant compressive/tensile loads. The tester design allows one to apply cyclic shear loads up to 200 N while maintaining a constant axial load of up to 38 N in tension or compression. The tester is capable of maintaining the axial load to within a tolerance of ±0.5 N during the entirety of fatigue experiment. Carefully constructed test specimens of Sn3.0Ag0.5Cu solder joints were isothermally fatigued under systematically increased compressive and tensile loads imposed on the test specimen subject to repeated loading (R = 0) under lap-shear. In general, the imposition of the superposed compressive load increases the fatigue life of the solder joint compared to application of pure cyclic shear, while the imposition of the superposed tensile load decreases the fatigue life. At larger compressive loads, friction between fractured surfaces is responsible for significant energy dissipation during the cyclic load–unload cycles.